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1
Yang, Haifei, Yachao Pan, Lifen Hu, et al. "Antimicrobial resistance patterns and characterization of integrons in clinical isolates of Shigella from China." Canadian Journal of Microbiology 60, no. 4 (2014): 237–42. http://dx.doi.org/10.1139/cjm-2013-0893.
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One hundred fifty-three Shigella isolates were examined for multiple antibiotic resistance phenotypes and prevalence of class 1 and class 2 integron sequences. The gene cassettes dfrA17-aadA5, dfrA12-orfF-aadA2, and arr-3-aacA4 were found in typical class 1 integrons. The gene cassettes blaOXA-1-aadA1 and dfrA1-sat1-aadA1 were detected in atypical class 1 integrons and in class 2 integrons, respectively. This is the first report of arr-3-aacA4 cassette detected in typical class 1 integrons among Shigella isolates. Rates of antibiotic resistance were different between integron-positive and integron-negative strains (P < 0.05), and all integron-positive isolates were resistant to at least 3 different antimicrobial agents. Typical class 1 integron-positive isolates showed higher resistance rates to cefotaxime and ciprofloxacin than did integron-negative ones (P < 0.05). Typical class 1 integrons and β-lactamase genes were found in conjugative plasmids, otherwise class 2 and atypical class 1 integrons were located on chromosome. This study demonstrated the wide distribution of class 1 integrons in Shigella spp., which may lead resistance to cefotaxime and ciprofloxacin in China.
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Ploy, Marie-Cécile, François Denis, Patrice Courvalin, and Thierry Lambert. "Molecular Characterization of Integrons inAcinetobacter baumannii: Description of a Hybrid Class 2 Integron." Antimicrobial Agents and Chemotherapy 44, no. 10 (2000): 2684–88. http://dx.doi.org/10.1128/aac.44.10.2684-2688.2000.
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ABSTRACT Twenty Acinetobacter baumannii strains resistant to various antibiotics were analyzed for integron content and sequences of the amplification products. Sixteen clinical isolates had a class 1 integron, 2 contained an additional class 1 or class 2 integron, but no class 3 integron was detected. Thirteen strains had integrons with a single cassette: aac(3)-Ia (9 strains), ant(2")-Ia (2 strains), or aac(6′)-Ib (2 strains); 1 hadaac(6′)-Ib and oxa20cassettes and an unknown gene; and 1 had an integron containingant(2")-Ia and an oxa3cassette truncated by IS6100. The remaining strains harbored class 1 integrons with gene cassettes previously found inEnterobacteriaceae. One integron had a hybrid structure composed of intI2 and the 3′ conserved segment of class 1 integrons. These data indicate that integrons play a major role in multidrug resistance in Acinetobacter.
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Ahmed, Ali Mhawesh, Naeem Ibraheem Reem, and Husham Zedan Tamara. "Enterobacter Cloacae: The association of antibiotic resistance, integron class I and carbapenemase genes." World Journal of Advanced Research and Reviews 12, no. 2 (2021): 549–54. https://doi.org/10.5281/zenodo.5773345.
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The opportunistic pathogen, E. <em>Cloacae</em> has been reported to carry carbapenemas genes worldwide. Our objective was assessing the association of antibiotic resistance, integron class I and carbapenemase genes among E. <em>Cloacae</em>. Herein, 200 E. <em>Cloacae</em> were collected and identified. The antibiotic resistance of them was evaluated using Kirby Bauer method. The existence of class I integron, carbapenemase genes was investigated using polymerase chain reaction (PCR). Of the 200 E. <em>Cloacae</em> isolates collected, 120 isolates (60%) were from male and 80 isolates (40%) were from females. Of them, 110 isolates (55%) showed a pattern of MDR phenotype. Of these, 18 isolates (9%) showed resistance to imipenem. Based on PCR test, 134 isolates (67%) had class I integrons. Also, out of 110 MDR isolates, 52 isolates (72%) were positive in terms of the presence of class I integrons. Isolates with integrons were mostly from urinary (61%) and blood (44%) and from ICU settings (46%) and inpatients (38%). A significant relationship was observed between the presence of integron and resistance to ciprofloxacin, imipenem, meropenem, and norfloxacin antibiotics. The prevalence of blaIMP, blaOXA-48 were 18% and 4%, respectively, but none of other carbapenemase genes were detected. The existence of class I integron was high among E. <em>Cloacae</em> from Baghdad city. The carriage of genes resistance to carbapenems were significantly associated to the class I integrin.
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Ahmed Ali Mhawesh, Reem Naeem Ibraheem, and Tamara Husham Zedan. "Enterobacter Cloacae: The association of antibiotic resistance, integron class I and carbapenemase genes." World Journal of Advanced Research and Reviews 12, no. 2 (2021): 549–50. http://dx.doi.org/10.30574/wjarr.2021.12.2.0464.
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The opportunistic pathogen, E. Cloacae has been reported to carry carbapenemas genes worldwide. Our objective was assessing the association of antibiotic resistance, integron class I and carbapenemase genes among E. Cloacae. Herein, 200 E. Cloacae were collected and identified. The antibiotic resistance of them was evaluated using Kirby Bauer method. The existence of class I integron, carbapenemase genes was investigated using polymerase chain reaction (PCR). Of the 200 E. Cloacae isolates collected, 120 isolates (60%) were from male and 80 isolates (40%) were from females. Of them, 110 isolates (55%) showed a pattern of MDR phenotype. Of these, 18 isolates (9%) showed resistance to imipenem. Based on PCR test, 134 isolates (67%) had class I integrons. Also, out of 110 MDR isolates, 52 isolates (72%) were positive in terms of the presence of class I integrons. Isolates with integrons were mostly from urinary (61%) and blood (44%) and from ICU settings (46%) and inpatients (38%). A significant relationship was observed between the presence of integron and resistance to ciprofloxacin, imipenem, meropenem, and norfloxacin antibiotics. The prevalence of blaIMP, blaOXA-48 were 18% and 4%, respectively, but none of other carbapenemase genes were detected. The existence of class I integron was high among E. Cloacae from Baghdad city. The carriage of genes resistance to carbapenems were significantly associated to the class I integrin.
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Gupta, Renu, Sneh Lata Chauhan, Sunil Kumar, Naresh Jindal, N. K. Mahajan, and V. G. Joshi. "Carriage of Class 1 integrons and molecular characterization of intI1 gene in multidrug-resistant Salmonella spp. isolates from broilers." Veterinary World 12, no. 4 (2019): 609–13. http://dx.doi.org/10.14202/vetworld.2019.609-613.
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Aim: The present study was conducted with the following aims: (i) To screen the Salmonella spp. isolates recovered from suspected cases of fowl typhoid for carriage of Class 1 integrons and analyze their association with antimicrobial resistance and (ii) to carry out molecular characterization and phylogenetic analysis of Class 1 integron-integrase (intI1) gene. Materials and Methods: A total of 43 Salmonella isolates were subjected to polymerase chain reaction (PCR) assay to determine the presence of Class1 intI1. Differences between different serotypes in relation to their carriage of integrons and the differences between strains containing or not containing an integron and being resistant to different antimicrobials were analyzed by Fisher exact test using STATA™ (StataCorp, College Station, TX). Phylogenetic analysis was carried out using MEGA6 software. Results: Out of 43 isolates, 40 (93.02%) were found positive for Class 1 integrons. 35/40 (87.5%) intI1-positive isolates were multidrug resistance (MDR) (resistant to ≥4 antibiotics), which support the hypothesis of an association between the presence of Class 1 integrons and emerging MDR in Salmonella. There was no significant difference among isolates resistant to different antimicrobials in Class 1 integron carrying isolates and the Class 1 integron negative isolates (p<0.05). Further, there was no significant difference among different serotypes in respect of their carriage of Class 1 integrons. Conclusion: It can be concluded that the high prevalence of Class 1 integrons indicates a high potential of Salmonella isolates for horizontal transmission of antimicrobial genes, especially among Gram-negative organisms.
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Collis, Christina M., Mi-Jurng Kim, Sally R. Partridge, H. W. Stokes, and Ruth M. Hall. "Characterization of the Class 3 Integron and the Site-Specific Recombination System It Determines." Journal of Bacteriology 184, no. 11 (2002): 3017–26. http://dx.doi.org/10.1128/jb.184.11.3017-3026.2002.
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ABSTRACT Integrons capture gene cassettes by using a site-specific recombination mechanism. As only one class of integron and integron-determined site-specific recombination system has been studied in detail, the properties of a second class, the only known class 3 integron, were examined. The configuration of the three potentially definitive features of integrons, the intI3 gene, the adjacent attI3 recombination site, and the Pc promoter that directs transcription of the cassettes, was similar to that found in the corresponding region (5′ conserved segment) of class 1 integrons. The integron features are flanked by a copy of the terminal inverted repeat, IRi, from class 1 integrons on one side and a resolvase-encoding tniR gene on the other, suggesting that they are part of a transposable element related to Tn402 but with the integron module in the opposite orientation. The IntI3 integrase was active and able to recognize and recombine both known types of IntI-specific recombination sites, the attI3 site in the integron, and different cassette-associated 59-be (59-base element) sites. Both integration of circularized cassettes into the attI3 site and excision of integrated cassettes were also catalyzed by IntI3. The attI3 site was localized to a short region adjacent to the intI3 gene. Recombination between a 59-be and secondary sites was also catalyzed by IntI3, but at frequencies significantly lower than observed with IntI1, the class 1 integron integrase.
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Öner, Sedef Zeliha, Hatice Er, Ahmet Çalışkan, Melek Demir, Hande Şenol, and İlknur Kaleli. "An evaluation of clonal relationship by PFGE method in Acinetobacter baumannii isolates, examining integron presence and antibiotic resistance." Journal of Infection in Developing Countries 18, no. 12 (2024): 1922–29. https://doi.org/10.3855/jidc.20021.
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Introduction: This study aims to investigate the presence of class 1, 2, and 3 integrons in Acinetobacter baumannii isolates, evaluate the relationship between integrons and antibiotic resistance and determine the clonal relationship between isolates by PFGE method. Methodology: A total of 188 A. baumannii strains between February 2020 and March 2023 were included in the study. The antibiotic susceptibility was assessed per the recommendations of “The European Committee on Antimicrobial Susceptibility Testing”. Integrons have been identified by polymerase chain reaction. The clonal relationship between isolates was evaluated with PFGE. Results: Integron carriage was observed in 45.7% of isolates. Of these, 44.1% carried class 0.5% carried class 2, and 2 (1.1%) carried both classes of integrons. Among the integron positive isolates, the rate of only class 1 integron was 96.5% (83/86), the rate of only class 2 was 1.2% (1/86), and the rate of only two integron classes together was 2.3% (2/86). In the presence of class 1 integrons, the MDR and XDR phenotypes were found to be high (p = 0.005, p = 0.029). PFGE method detected 26 clusters and 177 pulsotypes on the dendrogram. When the clusters are evaluated separately within themselves, in all of the isolates in the Y and Z clusters (100%), class 1 integron positivity was observed in cluster A at 52.2%, cluster J at 42.1%, and cluster N at 22.2%. Conclusions: Class 1 integron positivity observed in all of the isolates in the two clusters suggests the likelihood of clonal transfer alongside the horizontal transfer.
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NAGACHINTA, SUPAKANA, and JINRU CHEN. "Integron-Mediated Antibiotic Resistance in Shiga Toxin–Producing Escherichia coli." Journal of Food Protection 72, no. 1 (2009): 21–27. http://dx.doi.org/10.4315/0362-028x-72.1.21.
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This study was undertaken to characterize the integrons present in a group of Shiga toxin–producing Escherichia coli (STEC) isolates and the ability of these integrons to transfer antibiotic resistance genes from STEC to E. coli K-12 MG1655. A total of 177 STEC isolates were analyzed for antibiotic susceptibility and the presence of integrons. Class 1 integrons were detected in 14 STEC isolates, and a class 2 integron was identified in 1 STEC isolate. The STEC isolates positive for class 1 integrons were resistant to streptomycin (MICs &gt; 128 μg/ml) and sulfisoxazole (MICs &gt; 1,024 μg/ml), and the isolate positive for the class 2 integron was resistant to streptomycin (MIC of 128 μg/ml), trimethoprim (MIC &gt; 256 μg/ml), and streptothricin (MIC &gt; 32 μg/ml). Results of restriction digestion and nucleotide sequencing revealed that the cassette regions of the class 1 integrons had a uniform size of 1.1 kb and contained a nucleotide sequence identical to that of aadA1. The class 2 integron cassette region was 2.0 kb and carried nucleotide sequences homologous to those of aadA1, sat1, and dfrA1. Results of the conjugation experiments revealed that horizontal transfers of conjugative plasmids are responsible for the dissemination of class 1 integron–mediated antibiotic resistance genes from STEC to E. coli K-12 MG1655. Antibiotic resistance traits not mediated by integrons, such as resistance to tetracycline and oxytetracycline, were cotransferred with the integron-mediated antibiotic resistance genes. The study suggested a possible role of integron and conjugative plasmid in dissemination of genes conferring resistance to antibiotics from pathogenic to generic E. coli cells.
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Wang, Yu, Bingbing Kong, Wenping Yang, and Xin Zhao. "Correlation between class 1 integron of Escherichia coli and multidrug resistance in lower respiratory tract infection." Journal of Infection in Developing Countries 11, no. 08 (2017): 604–10. http://dx.doi.org/10.3855/jidc.8247.
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Introduction: Class 1 integrons are mobile genetic elements considered to be responsible for the transfer of multidrug resistance. This study aimed to investigate the distribution of type 1 integrons in multidrug-resistantEscherichiacolifrom hospital-acquired lower respiratory tract infections.
 Methodology: Clinical strains of E. coli were isolated from patients with hospital-acquired lower respiratory tract infections in the emergency intensive care unit from January to December 2014. Drug sensitivity testing was performed using the Kirby-Bauer method. The combination disk method was used to detect extended-spectrum β-lactamase (ESBL), and polymerase chain reaction (PCR) amplification was used to detect the intI1 gene.
 Results: Among 58 E. coli strains, resistance to β-lactam antibiotics ranked as follows: imipenem (0.0%), cefoperazone/sulbactam sodium (25.9%), ceftazidime (37.9%), and cefepime (39.7%); other β-lactam antibiotic resistance rates were all > 50%. The resistance rates to amikacin, ciprofloxacin, gentamicin, and cotrimoxazole were32.8%, 63.8%, 70.7%, and 81.0%, respectively. In total, 31 (53.4%) isolates were positive for class 1 integron and carried 4 different sizes of amplification fragments: 800, 1,600, 1,900, and 2,600 bp. Among 43 ESBL-positive isolates, 27 (62.8%) also carried class 1 integron; among 15 ESBL-negative isolates, 4 carried class 1 integron (26.7%). The positive rate for class 1 integron in ESBL-producing strains was significantly higher than that in non-ESBL-producing strains. The rates of resistance of integron-positive isolates to ceftriaxone, cefotaxime, amikacin, ciprofloxacin, and cotrimoxazole were significantly higher than those in integron-negative isolates.
 Conclusions: Class 1 integrons are widely distributed in E. coli and are associated with multidrug resistance.
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Sajjad, Ammara, Marita P. Holley, Maurizio Labbate, H. W. Stokes, and Michael R. Gillings. "Preclinical Class 1 Integron with a Complete Tn402-Like Transposition Module." Applied and Environmental Microbiology 77, no. 1 (2010): 335–37. http://dx.doi.org/10.1128/aem.02142-10.
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ABSTRACTThe presence of integrons was assessed in gut bacteria isolated from wild-caught prawns. A pseudomonad was recovered that contained a Tn402-like class 1 integron with a complete transposition module and two gene cassettes. One cassette was identical to a previously described cassette from a chromosomal class 3 integron inDelftiatsuruhatensis.
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Arduino, Sonia M., Mariana Catalano, Betina E. Orman, Paul H. Roy, and Daniela Centrón. "Molecular Epidemiology of orf513-Bearing Class 1 Integrons in Multiresistant Clinical Isolates from Argentinean Hospitals." Antimicrobial Agents and Chemotherapy 47, no. 12 (2003): 3945–49. http://dx.doi.org/10.1128/aac.47.12.3945-3949.2003.
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ABSTRACT The spread of orf513-bearing class 1 integrons is associated with bla CTX-M-2 in gram-negative clinical isolates in Argentina, with In35 being the most frequently found integron (74%). Among 65 isolates without bla CTX-M-2, only one harbored a novel orf513-bearing class 1 integron with the dfrA3b gene. The finding of orf513 not associated with class 1 integrons in two gram-positive strains indicates the widespread occurrence of this putative site-specific recombinase.
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PEYMANI, AMIR, SAFAR FARAJNIA, MOHAMMAD REZA NAHAEI, et al. "Prevalence of Class 1 Integron among Multidrug-Resistant Acinetobacter baumannii in Tabriz, Northwest of Iran." Polish Journal of Microbiology 61, no. 1 (2012): 57–60. http://dx.doi.org/10.33073/pjm-2012-007.
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Integrons are associated with a variety of gene cassettes, which confer resistance to multiple classes of antibacterial drugs. In this study we tested the frequency of class 1 and 2 integrons among multidrug-resistant Acinetobacter baumannii (MDRAB) clinical isolates. One hundred clinical isolates of A. baumannii were screened for carriage of class 1 and 2 integrons by PCR method. Results showed that seventy four (92.5%) of 80 MDRAB carried class 1 integron. Integron-positive isolates were statistically more resistant to aminoglycoside, quinolone and beta-lactam compounds except for cefepime. This is the first report of class 1 integrons in MDRAB isolates in northwest Iran.
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Márquez, Carolina, Maurizio Labbate, Ana J. Ingold, et al. "Recovery of a Functional Class 2 Integron from an Escherichia coli Strain Mediating a Urinary Tract Infection." Antimicrobial Agents and Chemotherapy 52, no. 11 (2008): 4153–54. http://dx.doi.org/10.1128/aac.00710-08.
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ABSTRACT A class 2 integron was found in an Escherichia coli isolate mediating a urinary tract infection. Unlike other class 2 integrons from pathogens, the encoded IntI2 protein was functional. The integron possessed a dfrA14 cassette, and a second novel cassette in which a lipoprotein signal peptidase gene is predicted.
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Rao, Sangeeta, Lyndsey Linke, Enrique Doster, et al. "Genomic diversity of class I integrons from antimicrobial resistant strains of Salmonella Typhimurium isolated from livestock, poultry and humans." PLOS ONE 15, no. 12 (2020): e0243477. http://dx.doi.org/10.1371/journal.pone.0243477.
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Introduction Multidrug resistance (MDR) is a serious issue prevalent in various agriculture-related foodborne pathogens including Salmonella enterica (S. enterica) Typhimurium. Class I integrons have been detected in Salmonella spp. strains isolated from food producing animals and humans and likely play a critical role in transmitting antimicrobial resistance within and between livestock and human populations. Objective The main objective of our study was to characterize class I integron presence to identify possible integron diversity among and between antimicrobial resistant Salmonella Typhimurium isolates from various host species, including humans, cattle, swine, and poultry. Methods An association between integron presence with multidrug resistance was evaluated. One hundred and eighty-three S. Typhimurium isolates were tested for antimicrobial resistance (AMR). Class I integrons were detected and sequenced. Similarity of AMR patterns between host species was also studied within each integron type. Results One hundred seventy-four (95.1%) of 183 S.Typhimurium isolates were resistant to at least one antimicrobial and 82 (44.8%) were resistant to 5 or more antimicrobials. The majority of isolates resistant to at least one antimicrobial was from humans (45.9%), followed by swine (19.1%) and then bovine (16.9%) isolates; poultry showed the lowest number (13.1%) of resistant isolates. Our study has demonstrated high occurrence of class I integrons in S. Typhimurium across different host species. Only one integron size was detected in poultry isolates. There was a significant association between integron presence of any size and specific multidrug resistance pattern among the isolates from human, bovine and swine. Conclusions Our study has demonstrated a high occurrence of class I integrons of different sizes in Salmonella Typhimurium across various host species and their association with multidrug resistance. This demonstration indicates that multidrug resistant Salmonella Typhimurium is of significant public health occurrence and reflects on the importance of judicious use of antimicrobials among livestock and poultry.
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Abed, Esraa S., and Munim R. Ali. "Identification of class I, II, and III Integron genes in multidrug-resistant Acinetobacter baumannii strains." Journal of Applied and Natural Science 16, no. 2 (2024): 874–82. http://dx.doi.org/10.31018/jans.v16i2.5519.
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Integrons are one genetic factor that can contribute to the high prevalence of antibiotic resistance among Acinetobacter baumannii isolates and their spread. This research aimed to study the prevalence of class 1,2 and 3 integron in A. baumannii isolates and their relatedness to virulence factors of antibiotics resistance. Seventy clinical isolates of A.baumannii were isolated from several sources such as blood, urinary tract infection (UTI), sputum, urine, and cerebrospinal fluid (CSF). First, the isolates were identified and characterized according to certain morphology, cultural and biochemical tests. Second genotypic ally Identification of the isolates was confirmed by Polymerase chain reaction (PCR), which was performed by housekeeping gene 16sRNA and by (blaOxa 51gene) for A. baumannii species. The antimicrobial susceptibility technique was evaluated through disk diffusion methods. These isolates resistant to various antibiotics were analyzed for integron class I, II and III content and sequences of the amplification products by PCR. The findings showed that the predominant A. baumannii isolates were multidrug resistant and they were most resistant to 15 antibiotics. The higher resistance of A. baumannii to Gatifloxacin and lower resistance to polymyxin. Sixty clinical Multidrug resistance (MDR) isolates of A. baumannii had class I integron and five class III integron, but class II integron was not detected in the isolates. This revealed that the dissemination of MDR among A. baumannii may be associated with the presence of integrons class I and class III. These data indicate that integrons are gene cassettes containing antibiotic-resistance genes that play a major role in the virulence characteristics of MDR and Extensively-drug resistance (XDR) in Acinetobacter baumannii.
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Byrne-Bailey, K. G., W. H. Gaze, L. Zhang, et al. "Integron Prevalence and Diversity in Manured Soil." Applied and Environmental Microbiology 77, no. 2 (2010): 684–87. http://dx.doi.org/10.1128/aem.01425-10.
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ABSTRACTThe levels of integron abundance and diversity in soil amended with pig slurry were studied. Real-time PCR illustrated a significant increase in class 1 integron prevalence after slurry application, with increased prevalence still evident at 10 months after application. Culture-dependent data revealed 10 genera, including putative human pathogens, carrying class 1 and 2 integrons.
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M. khadhim, Manal, and Meraim A. Kazaal. "Association Between Antibiotic Resistance and Integron Class2 Among Commonsal Escherichia coli Genotypic Groups." AL-QADISIYAH MEDICAL JOURNAL 14, no. 25 (2018): 14–26. http://dx.doi.org/10.28922/qmj.2018.14.25.14-26.
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Antibiotic therapies can not affect only on the pathogenic bacteria, but also commensal microorganisms in the humans gut, which might serve as a reservoir of antimicrobial resistance genes. fecal Escherichia coli (E. coli) is often considered as a good indicator for selection pressure imposed by antimicrobial use. The goal of this study was to determine genotyping groups of commonsal E. coli and investigate the frequency of integrons class 2 and antibiotic resistance among them. So detect the association of integron class2 with antibiotic resistance (single and multiple drug resistance) that may be transport horizontally in bacterial populations. In this study 301isolates of commonsal E. coli were isolated from stools obtained from healthy individuals with age from 1to 80 years. All isolates were tested for their susceptibility against 16 antimicrobial agents and subjected to conventional polymerase chain reactions (PCR) for detection integrons and multiplex PCR for genotyping analysis. Present results showed that group B2 represent the majority of the collected isolates
 (63%) followed by group A (23%) and D (14%) but no strains were found to belong to group B1. Also results revealed that 10% of isolates have integron class 2 that mainly related to genotypic group B2. High resistance observed for most antibiotics especially ampicilln, amoxcillin, lincomycin, cephalexin while resistance to amikacin and gentamicin was less common. Antibiotic resistance mainly appeared in integron positive isolates. In conclusion, high prevalence of antibiotic resistance especially among integron class 2 positive isolates that indicated role of gut flora as reservoir and source of antibiotic resistance. 
 Antibiotic therapies can not affect only on the pathogenic bacteria, but also commensal microorganisms in the humans gut, which might serve as a reservoir of antimicrobial resistance genes. fecal Escherichia coli (E. coli) is often considered as a good indicator for selection pressure imposed by antimicrobial use. The goal of this study was to determine genotyping groups of commonsal E. coli and investigate the frequency of integrons class 2 and antibiotic resistance among them. So detect the association of integron class2 with antibiotic resistance (single and multiple drug resistance) that may be transport horizontally in bacterial populations. In this study 301isolates of commonsal E. coli were isolated from stools obtained from healthy individuals with age from 1to 80 years. All isolates were tested for their susceptibility against 16 antimicrobial agents and subjected to conventional polymerase chain reactions (PCR) for detection integrons and multiplex PCR for genotyping analysis. Present results showed that group B2 represent the majority of the collected isolates
 (63%) followed by group A (23%) and D (14%) but no strains were found to belong to group B1. Also results revealed that 10% of isolates have integron class 2 that mainly related to genotypic group B2. High resistance observed for most antibiotics especially ampicilln, amoxcillin, lincomycin, cephalexin while resistance to amikacin and gentamicin was less common. Antibiotic resistance mainly appeared in integron positive isolates. In conclusion, high prevalence of antibiotic resistance especially among integron class 2 positive isolates that indicated role of gut flora as reservoir and source of antibiotic resistance.
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Martínez, T., G. J. Vazquez, E. E. Aquino, R. V. Goering та I. E. Robledo. "Two Novel Class I Integron Arrays Containing IMP-18 Metallo-β-Lactamase Gene in Pseudomonas aeruginosa Clinical Isolates from Puerto Rico". Antimicrobial Agents and Chemotherapy 56, № 4 (2012): 2119–21. http://dx.doi.org/10.1128/aac.05758-11.
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ABSTRACTDuring a β-lactam resistance surveillance study, 12 IMP-18-positivePseudomonas aeruginosaisolates belonging to 9 different pulsed-field gel electrophoresis groups were identified. In nine isolates, a class I integron with a novel gene array was identified that containedblaIMP-18andblaOXA-224, while in two isolates the class I integron containedblaIMP-18andblaOXA-2but in a new arrangement. Our findings show the dissemination of two novel class I integrons inP. aeruginosafrom different regions of Puerto Rico.
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YOSBOONRUANG, Atchariya, Anong KIDDEE, Chatsuda BOONDUANG, and Phannarai PIBALPAKDEE. "Integron Expression in Multidrug-Resistant Escherichia coli Isolated from House Flies within the Hospital." Walailak Journal of Science and Technology (WJST) 16, no. 5 (2018): 319–27. http://dx.doi.org/10.48048/wjst.2019.6286.
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Escherichia coli is a serious cause of a variety of hospital-acquired infections and commonly contributes to the environment by house flies. Integrons, particularly class 1 integrons, are the genetic elements that play an important role in the horizontal transfer of antimicrobial resistance mechanism. This mechanism is commonly found in Enterobacteriaceae, especially E. coli. In this study, we aim to investigate the occurrence and antimicrobial resistance patterns of E. coli isolated from the house flies in Phayao hospital and to determine the gene expression of class 1 integrons in those isolates of E. coli. Totally, 70 isolates of E. coli were isolated from 60 house flies collected from the hospital. Fifty-seven of the isolates (81.43 %) were multidrug resistance (MDR) and highly resistant to b-lactams, tetracyclines, and sulfonamides. Of 57 isolates of MDR-E. coli, 20 isolates (35 %) were found to carry class 1 integron genes. Fifteen patterns of antimicrobial resistance occurred in the isolates of integron-positive E. coli. Most integron-positive E. coli isolates were resistant to 7 antimicrobials. Two isolates of these bacteria (10 %) were able to resist 13 out of 14 tested antimicrobials. Using PCR and sequencing analysis, an investigation showed that dfrA17-aadA5, dfrA12-aadA2 gene cassette was the most prevalent cassette (n = 10; 50 %) among the integron-positive E. coli isolates. Our results indicated that the presences of multidrug resistance and class 1 integrons were common in E. coli isolated from the houseflies in hospital. Therefore, screening for integron-positive E. coli from the hospital environment might be necessary for prevention of nosocomial infections.
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Libisch, Balázs, Mária Gacs, Károly Csiszár, Mónika Muzslay, László Rókusz та Miklós Füzi. "Isolation of an Integron-Borne blaVIM-4 Type Metallo-β-Lactamase Gene from a Carbapenem-Resistant Pseudomonas aeruginosa Clinical Isolate in Hungary". Antimicrobial Agents and Chemotherapy 48, № 9 (2004): 3576–78. http://dx.doi.org/10.1128/aac.48.9.3576-3578.2004.
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ABSTRACT The first integron-borne metallo-β-lactamase gene was isolated in Hungary. The bla VIM-4 gene is located on a class 1 integron that also carries a novel bla OXA-like gene. The integron is harbored by a serotype O12 Pseudomonas aeruginosa strain and shows high structural similarity to integrons isolated in Greece and Poland.
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Xu, Zhenbo, Lin Li, Lei Shi, and Mark E. Shirtliff. "Class 1 integron in staphylococci." Molecular Biology Reports 38, no. 8 (2011): 5261–79. http://dx.doi.org/10.1007/s11033-011-0676-7.
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Labbate, M., P. Roy Chowdhury, and H. W. Stokes. "A Class 1 Integron Present in a Human Commensal Has a Hybrid Transposition Module Compared to Tn402: Evidence of Interaction with Mobile DNA from Natural Environments." Journal of Bacteriology 190, no. 15 (2008): 5318–27. http://dx.doi.org/10.1128/jb.00199-08.
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ABSTRACT In a survey of class 1 integrons from human stools, an unusual class 1 integron from a strain of Enterobacter cloacae was isolated and characterized in detail. Sequence analysis of a fosmid containing the class 1 integron revealed a complex set of transposons which included two Tn402-like transposons. One of these transposons, Tn6007, included a class 1 integron with two non-antibiotic-resistance-type gene cassettes and a complete transposition module. This tni module is a hybrid with a boundary within the res site compared to Tn402, implying that a site-specific recombination event generated either Tn6007 or Tn402. The second Tn402-like transposon, Tn6008, possesses neither a mer operon nor an integron, and most of its tni module has been deleted. Tn6007, Tn6008, and the 2,478 bases between them, collectively designated Tn6006, have transposed into a Tn5036/Tn3926-like transposon as a single unit. Tn6006, Tn6007, and Tn6008 could all transpose as discrete entities. Database analysis also revealed that a version of Tn6008 was present in the genome of Xanthomonas campestris pv. vesicatoria. Overall, the E. cloacae isolate further demonstrated that functional class 1 integrons/transposons are probably common in bacterial communities and have the potential to add substantially to the problem of multidrug-resistant nosocomial infections.
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Rodríguez, Irene, M. Rosario Rodicio, M. Carmen Mendoza, and M. Cruz Martín. "Large Conjugative Plasmids from Clinical Strains of Salmonella enterica Serovar Virchow Contain a Class 2 Integron in Addition to Class 1 Integrons and Several Non-Integron-Associated Drug Resistance Determinants." Antimicrobial Agents and Chemotherapy 50, no. 4 (2006): 1603–7. http://dx.doi.org/10.1128/aac.50.4.1603-1607.2006.
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ABSTRACT Two large conjugative resistance (R) plasmids from clinical strains of Salmonella enterica serovar Virchow carried a class 2 integron with the 5′ conserved sequence (5′CS)-dfrA1-sat1-aadA1-3′CS gene array, which is associated with defective Tn7 transposons. In addition, each contained a different class 1 integron (with 5′CS-aadA1-3′CS or 5′CS-sat-smr-aadA1-3′CS gene arrays) linked to Tn21-Tn9 sequences, and several non-integron-associated R determinants. An intact copy of Tn7 (including the class 2 integron) was present in the chromosome of each strain.
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Miko, Angelika, Karin Pries, Andreas Schroeter, and Reiner Helmuth. "Multiple-Drug Resistance in d-Tartrate-Positive Salmonella enterica Serovar Paratyphi B Isolates from Poultry Is Mediated by Class 2 Integrons Inserted into the Bacterial Chromosome." Antimicrobial Agents and Chemotherapy 47, no. 11 (2003): 3640–43. http://dx.doi.org/10.1128/aac.47.11.3640-3643.2003.
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ABSTRACT The presence of integrons in 85 multiresistant German isolates of the predominating Salmonella enterica subsp. enterica serovar Paratyphi B dT+ clone was investigated. All isolates possessed a chromosomally located Tn7-like class 2 integron carrying the same dfrA1-sat1-aadA1 array of gene cassettes. Only four isolates (4.7%) revealed an additional class 1 integron with two strains each containing the aadA1 or dfrA1-aadA1 gene cassettes.
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Eshaghi Zadeh, Seyedeh Hanieh, Hossein Fahimi, Fatemeh Fardsanei, and Mohammad Mehdi Soltan Dallal. "Antimicrobial Resistance and Presence of Class 1 Integrons Among Different Serotypes of Salmonella spp. Recovered From Children with Diarrhea in Tehran, Iran." Infectious Disorders - Drug Targets 20, no. 2 (2020): 160–66. http://dx.doi.org/10.2174/1871526519666190130171020.
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Background: Salmonellosis is a major food-borne disease worldwide. The increasing prevalence of antimicrobial resistance among food-borne pathogens such as Salmonella spp. is concerning. Objective: The main objective of this study is to identify class 1 integron genes and to determine antibiotic resistance patterns among Salmonella isolates from children with diarrhea. Methods: A total of 30 Salmonella isolates were recovered from children with diarrhea. The isolates were characterized for antimicrobial susceptibility and screened for the presence of class 1 integron genes (i.e. intI1, sulI1, and qacEΔ1). Results: The most prevalent serotype was Enteritidis 36.7%, followed by Paratyphi C (30%), and Typhimurium (16.7%). The highest rates of antibiotic resistance were obtained for nalidixic acid (53.3%), followed by streptomycin (40%), and tetracycline (36.7%). Regarding class 1 integrons, 36.7%, 26.7%, and 33.3% of the isolates carried intI1, SulI, and qacEΔ1, respectively, most of which (81.8%) were multidrug-resistant (MDR). Statistical analysis revealed that the presence of class 1 integron was significantly associated with resistance to streptomycin and tetracycline (p = 0.042). However, there was no association between class 1 integron and other antibiotics used in this study (p > 0.05). Conclusion: The high frequency of integron class 1 gene in MDR Salmonella strains indicates that these mobile genetic elements are versatile among different Salmonella serotypes, and associated with reduced susceptibility to many antimicrobials.
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Xu, Hai, Julian Davies, and Vivian Miao. "Molecular Characterization of Class 3 Integrons from Delftia spp." Journal of Bacteriology 189, no. 17 (2007): 6276–83. http://dx.doi.org/10.1128/jb.00348-07.
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ABSTRACT Two environmental strains, Delftia acidovorans C17 and Delftia tsuruhatensis A90, were found to carry class 3 integrons, which have seldom been reported and then only from pathogens in which they are associated with antibiotic resistance genes. The Delftia integrons comprised a highly conserved class 3 integrase gene, upstream and oppositely oriented from a set of three or four gene cassettes that encoded unidentified functions. The A90 integron had one more gene cassette than the C17 integron, but the two were otherwise the same; furthermore, they were located within regions of sequence identity in both strains and linked to chromosomal genes. A screen of other Delftia and related strains did not reveal the presence of additional class 3 integrons. The observations suggest that these integrons were horizontally transferred to Delftia as part of a larger region and reside as chromosomal elements that probably predate transposon dissemination, as has been proposed for certain class 1 integrons.
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PHONGPAICHIT, SOUWALAK, SUMALEE LIAMTHONG, ALAN G. MATHEW, and USA CHETHANOND. "Prevalence of Class 1 Integrons in Commensal Escherichia coli from Pigs and Pig Farmers in Thailand." Journal of Food Protection 70, no. 2 (2007): 292–99. http://dx.doi.org/10.4315/0362-028x-70.2.292.
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Escherichia coli isolates (n = 617) from fecal samples of healthy and diarrheal pigs, pig farmers, and nonfarmers were analyzed for class 1 integrons. Three hundred ninety-two isolates (63.5%) were positive for class 1 integrons, based on the presence of intI1, with seventy-one of those isolates (11.5%) harboring all three conserved genes (intI1, qacEΔ1, and sul1) known to be associated with class 1 integrons. The presence of integrons was associated with isolate origin. Integrons were more prevalent in isolates from most pig groups than in isolates from pig farmers and nonfarmers. Selected integron-positive and integron-negative isolates were tested for resistance to 16 antimicrobials. All integron-positive swine isolates were multidrug resistant to at least three antimicrobial agents, demonstrating resistance to 14 different antibiotics that included sulphamethoxazole (100%), tetracycline (97.1%), ampicillin (92.8%), streptomycin (89.9%), trimethoprim-sulphamethoxazole (88.1%), nalidixic acid (60.9%), chloramphenicol (58.0%), kanamycin (55.1%), cephalothin (44.9%), gentamicin (39.1%), ciprofloxacin (33.3%), cefoxitin (8.7%), amoxicillin–clavulanic acid (5.8%), and amikacin (2.9%). All isolates were susceptible to ceftiofur and ceftriaxone. Forty-seven resistance patterns were observed among 69 integron-positive swine and swine farmer isolates. The most frequent pattern was tetracycline–ciprofloxacin–gentamicin–nalidixic acid–sulphamethoxazole–trimetho-prim-sulphamethoxazole–kanamycin–ampicillin–streptomycin (10.1%), which was found in diarrheal and healthy pigs. This study shows that integrons and multidrug-resistant commensal bacteria are common and appear to be a significant aspect of microbial communities associated with pigs and humans in southern Thailand.
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Savinova, T. A., Yu A. Bocharova, A. V. Lazareva, I. V. Chebotar, and N. A. Mayanskiy. "INTEGRON DIVERSITY IN BLAVIM-2-CARRYING CARBAPENEM-RESISTANT CLINICAL PSEUDOMONAS AERUGINOSA ISOLATES." Russian Clinical Laboratory Diagnostics 64, no. 8 (2019): 497–502. http://dx.doi.org/10.18821/0869-2084-2019-64-8-497-502.
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The growing prevalence of metallo-β-lactamase (MBL)-producing Pseudomonas aeruginosa in nosocomial pathogen populations has been attributed to their clonal spread, and/or horizontal transfer of MBL determinants in mobile genetic elements, including integrons. To characterize the genetic background of the beta-lactamase VIM-2 encoding gene in the population of carbapenem-resistant (Carba-R) P. aeruginosa clinical isolates.The detection of class 1 integrons was performed by PCR. Typing of the class 1 integrons containing the blaVIM gene cassette was performed by the PCR-restriction fragment length polymorphism (RFLP) approach followed by sequencing of variable regions of class 1 integrons. Five types of the blaVIM-2-carrying integrons were identified: ST654-isolates accounting for more than 50% of the Carba-R population harbored In56; ST235-isolates contained In559 (26% Carba-R isolates); ST111-isolates (19% Carba-R isolates) were characterized by carrying In59-like integron; two ST235-isolates harbored In59 and In249 each. Except In56, carrying the only blaVIM-2-gene cassette, all other identified integron types harbored the genes of resistance to trimethoprim and/or aminoglycosides. No new types of integrons were identified in the P. aeruginosa clinical isolates. The observed correlation of the integron type with specific STs indicates a clonal dissemination of significant resistance determinant producers - ST111, ST654 and ST235 epidemic lines. The features of the integron variable regions can be used for the epidemiological characterization of clinical P. aeruginosa isolates.
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Machado, Elisabete, Rafael Cantón, Fernando Baquero та ін. "Integron Content of Extended-Spectrum-β-Lactamase-Producing Escherichia coli Strains over 12 Years in a Single Hospital in Madrid, Spain". Antimicrobial Agents and Chemotherapy 49, № 5 (2005): 1823–29. http://dx.doi.org/10.1128/aac.49.5.1823-1829.2005.
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ABSTRACT The contribution of integrons to the dissemination of extended-spectrum β-lactamases (ESBL) was analyzed on all ESBL-producing Escherichia coli isolates from 1988 to 2000 at Ramón y Cajal Hospital. We studied 133 E. coli pulsed-field gel electrophoresis types: (i) 52 ESBL-producing clinical strains (C-ESBL) (16 TEM, 9 SHV, 21 CTX-M-9, 1 CTX-M-14, and 5 CTX-M-10); (ii) 43 non-ESBL blood clinical strains (C-nESBL); and (iii) 38 non-ESBL fecal isolates from healthy volunteers (V-nESBL). Class 1 integrons were more common among C-ESBL (67%) than among C-nESBL (40%) or V-nESBL (26%) (P < 0.001) due to the high number of strains with bla CTX-M-9 , which is linked to an In6-like class 1 integron. Without this bias, class 1 integron occurrence would be similar in C-ESBL and C-nESBL groups (47% versus 40%). Occurrence of class 2 integrons was similar among clinical and community isolates (13 to 18%). No isolates contained class 3 integrons. The relatively low rate of class 1 integrons within transferable elements carrying blaTEM (23%) or blaSHV (33%) and the absence of class 2 integrons in all ESBL transconjugants mirror the assembly of translocative pieces containing blaTEM or blaSHV on local available transferable elements lacking integrons. The low diversity of class 1 integrons (seven types recovered in all groups) might indicate a wide dissemination of specific genetic elements in which they are located. In our environment, the spread of genetic elements encoding ESBL has no major impact on the dispersion of integrons, nor do integrons have a major impact on the spread of ESBL, except when blaESBL genes are within an integron platform such as bla CTX-M-9 .
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Correia, Mário, Filipa Boavida, Filipa Grosso, et al. "Molecular Characterization of a New Class 3 Integron in Klebsiella pneumoniae." Antimicrobial Agents and Chemotherapy 47, no. 9 (2003): 2838–43. http://dx.doi.org/10.1128/aac.47.9.2838-2843.2003.
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ABSTRACT Klebsiella pneumoniae FFUL 22K was isolated in April 1999 from the urine of an intensive care unit patient in Portugal. The strain showed an extended-spectrum cephalosporin resistance profile. A typical synergistic effect between cefotaxime or cefepime and clavulanic acid was observed. An Escherichia coli transformant displayed a similar resistance phenotype and harbored a ca. 9.4-kb plasmid (p22K9). Cloning experiments revealed that the extended-spectrum β-lactamase was encoded by bla GES-1, previously described in class 1 integrons from K. pneumoniae ORI-1 and Pseudomonas aeruginosa Pa695. Further sequence analysis demonstrated that the bla GES-1 gene cassette was located on a new class 3 integron. The integron was 2,863 bp long and consisted of an intI3 integrase gene, an attI3 recombination site, two promoter regions, and two gene cassettes. The IntI3 integrase was 98.8% identical to that of Serratia marcescens AK9373. The bla GES-1 gene cassette was inserted at the attI3 site. The second gene cassette was the result of a fusion event between bla OXA-10-type and aac(6′)-Ib gene cassettes and conferred resistance to kanamycin. This is the second class 3 integron reported and the first time that the bla GES-1 gene cassette has been found on an integron belonging to this class, highlighting the considerable heterogeneity of their genetic environment and the spread of gene cassettes among different classes of integrons.
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Shariat, Afsoon, and Fatemeh Fathpoor. "Prevalence of Class I, II and III Integrons in Uropathogenic Escherichia Coli Strains Isolated from Patients with Urinary Tract Infection in Shiraz, Iran." Jundishapur Journal of Medical Sciences 21, no. 4 (2022): 500–513. http://dx.doi.org/10.32598/jsmj.21.4.2384.
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Background and Objectives Transfer of antibiotic resistance genes by integrons is the main cause of drug-resistant bacteria. This study aims to evaluate the prevalence of class I, II, and III integrons among uropathogenic Escherichia Coli (UPEC) strains isolated from patients with Urinary tract infection (UTI). Subjects and Methods This cross-sectional study was carried out on 50 UPEC strains isolated from patients with UTI referred to hospitals in Shiraz, Iran in 2020. Antibiotic susceptibility pattern was evaluated by the disk diffusion susceptibility test. Then, the prevalence of class 1 to 3 integrons in the isolates was investigated by the polymerase chain reaction test. Data were statistically analyzed in SPSS software using chi-square test. P≤0.05 was statistically significant. Results 42% of isolates had multi-drug resistance. The highest antibiotic resistance and sensitivity were related to trimethoprim/sulfamethoxazole (52%) and gentamicin (90%), respectively. There was a significant relationship between the presence of class I integron and resistance to amikacin and ciprofloxacin, between the presence of class II integron and resistance to gentamicin, and between the presence of class III integron and resistance to trimethoprim/sulfamethoxazole and nalidixic acid (P<0.05). Conclusion There is a significant association between the presence of class I, II and III integrons and antibiotic resistance in UPEC strains isolated from patients with UTI. Infection control measures and suitable treatment methods are needed for preventing the spread of these isolates in the hospitals and health centers in Shiraz city.
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Al-Jelehawy, Alaa Hamza Jaber, Baker Ghassan Nader, and Khadija Thaer Salah. "Dissemination of Integron Class 1 among XDR isolates of P. aeruginosa in Najaf City." South Asian Journal of Research in Microbiology 17, no. 4 (2023): 19–23. http://dx.doi.org/10.9734/sajrm/2023/v17i4336.
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Background: Integrons are gene capture systems observed in chromosomes, plasmids, and transposons, where identified and capture multiple gene cassettes. Integerons are consists of 3 elements: the initial is integrase gene (int1) encoding integrase enzyme (int1), which is essential to insertion or deletion of specific site. The second element is attI as integron-connected recombination site. The 3rd element is promoter (Pc), which is required in the expression of cassette-connected genes. 
 Aim of the Study: This thesis designed to examine the occurrence of integron class one genes among XDR isolates of P. aeruginosa. 
 Methods: An overall of 79 specimens were isolated from patients during the period of study and the specimens were carried to the laboratory. By monoplex PCR assay, the 19 XDR isolates of P. aeruginosa were investigated for the presence of integrons class one using intI1primer. 
 Results: This result found that 8 isolates are isolated from burns, 7 isolates are from urine, 4 isolates are from wounds. The PCR results show that 17 (89.5%) of the isolates harbored integrase (intI1) gene, while two isolate (10.5%) was negative for intI1 gene. Conclusions: Present result showed elevated occurrence of integrons class one among XDR isolates of P.aeruginosa.
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Huang, Jiangqing, Fangjun Lan, Yanfang Lu, and Bin Li. "Characterization of Integrons and Antimicrobial Resistance in Escherichia coli Sequence Type 131 Isolates." Canadian Journal of Infectious Diseases and Medical Microbiology 2020 (February 24, 2020): 1–8. http://dx.doi.org/10.1155/2020/3826186.
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Background. Escherichia coli sequence type 131 (ST131) is an important multidrug-resistant extraintestinal pathogen, which can cause many kinds of infections. Integrons may play a crucial role in the dissemination of antibiotic resistance genes. The purpose of this study was to characterize the prevelance of integrons among E. coli ST131 strains in China. Methods. Eighty-three E. coli ST131 isolates were used in this study. The antibiotic susceptibility test was performed by the disk diffusion method. The presence and characterization of class 1, 2, and 3 integrons, as well as promotor of gene cassettes and other antimicrobial resistance genes, were detected by PCR and DNA sequencing. Transfer of integrons was carried out using a broth culture mating method. Clonal relatedness of E. coli ST131 isolates was analyzed by PFGE. Results. Overall, 26.5% (22/83) of the E. coli ST131 isolates carried class 1 integrons. Class 2 and 3 integrons were not found in this study. Two types of gene cassette arrays were demonstrated in this study and were as follows: dfrA17-aadA5 and aac(6′)-Ib-cr-cmlA5. Only one type of Pc promoter variant was detected among 22 integron-positive isolates (PcW). In vivo transfer of integron was successful for 9 of integron-positive E. coli ST131 isolates harboring resistance gene cassettes. Results of PFGE demonstrated that the integron-positive E. coli ST131 isolates were grouped into 12 different PFGE clusters. Conclusions. Our study showed a low prevalence of integrons was detected in E. coli ST131. Continued surveillance of this mobile genetic element should be performed to study the evolution of antibiotic resistance among E. coli ST131.
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Valverde, Aránzazu, Rafael Cantón, Juan Carlos Galán, Patrice Nordmann, Fernando Baquero, and Teresa M. Coque. "In117, an Unusual In0-Like Class 1 Integron Containing CR1 and blaCTX-M-2 and Associated with a Tn21-Like Element." Antimicrobial Agents and Chemotherapy 50, no. 2 (2006): 799–802. http://dx.doi.org/10.1128/aac.50.2.799-802.2006.
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ABSTRACT An unusual In0-like class 1 integron containing a common region that includes the putative recombinase gene named orf513 (CR1) and bla CTX-M-2 was characterized from Escherichia coli. The integron contained an unusual gene cassette array, estX-aadA1, embedded between the 5′-conserved segment (5′-CS) and 3′-CS1 regions and was flanked by mer-Tn21 sequences downstream of the tni truncated module. This element constitutes one of the few examples of CR1-bearing class 1 integrons that has been fully characterized.
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Popoola, O. D., and B. T. Thomas. "Bioinformatic analysis of multi-drug resistant class 1 integron-coded protein of Citrobacter freundii." African Journal of Clinical and Experimental Microbiology 22, no. 3 (2021): 391–96. http://dx.doi.org/10.4314/ajcem.v22i3.10.
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Background: The understanding of the secondary structure of the class 1 integron coded protein is necessary to decipher potential drug target and also to infer evolutionary ancestry at the proteomic level. This study was therefore aimed at determining the secondary structure of class 1 integron-coded protein and also to provide information on their evolutionary ancestry.
 Methodology: Five different sequences of Citrobacter freundii with the following accession numbers; KP902625.1, KP902624.1, KP902623.1, KP901093.1 and KP902609.1 were obtained using nucleotide BLAST (http://blast. ncbi.nlm.nih.gov/Blast.cgi) and subjected to evolutionary analysis, pairwise distance calculation, secondary structure and neutrality test using MEGA explorer, Kimura 2 parameter, SOPMA tool and Tajima’s test respectively.
 Results: Results of the NCBI queries revealed significant identity with class 1 integron of the studied Citrobacter freundii. The nucleotide sequence alignment depicted several conserved regions with varying degree of transitions, transversions, insertions, and deletions while the amino acid sequences of the nucleotides showed 42 conserved sites among all the sequences. The secondary structure of the class 1 integron coded protein depicted significant representation of the random coil (43.74±3.24), alpha helix (25.69±6.29) and the extended strands (22.42±2.41) than the beta turns (8.15±1.12). The Tajima’s Neutrality test of five nucleotide sequences of Citrobacter freundii analyzed by considering the first, second and third codons as well as the non-coding regions revealed a total of 127 positions in the final datasets while the Tajima’s Neutrality test was estimated to be -0.1038.
 Conclusion: The study confirmed common evolutionary ancestor for the class 1 integron coded protein found in Citrobacter freundii. Our study also documents the higher representation of random coil, alpha helix and extended strands than the beta turns. The negative value of the Tajima’s neutrality test suggests higher levels of both low and high frequency polymorphisms thus indicating a decrease in the class 1 integron population size and balancing selection
 Keywords: Evolutionary, Protein structure, Class 1 integrons, Citrobacter freundii
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Bass, Lydia, Cynthia A. Liebert, Margie D. Lee, et al. "Incidence and Characterization of Integrons, Genetic Elements Mediating Multiple-Drug Resistance, in AvianEscherichia coli." Antimicrobial Agents and Chemotherapy 43, no. 12 (1999): 2925–29. http://dx.doi.org/10.1128/aac.43.12.2925.
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ABSTRACT Antibiotic resistance among avian bacterial isolates is common and is of great concern to the poultry industry. Approximately 36% (n = 100) of avian, pathogenic Escherichia coli isolates obtained from diseased poultry exhibited multiple-antibiotic resistance to tetracycline, oxytetracycline, streptomycin, sulfonamides, and gentamicin. Clinical avian E. coli isolates were further screened for the presence of markers for class 1 integrons, the integron recombinase intI1 and the quaternary ammonium resistance gene qacEΔ1, in order to determine the contribution of integrons to the observed multiple-antibiotic resistance phenotypes. Sixty-three percent of the clinical isolates were positive for the class 1 integron markersintI1 and qacEΔ1. PCR analysis with the conserved class 1 integron primers yielded amplicons of approximately 1 kb from E. coli isolates positive for intI1 andqacEΔ1. These PCR amplicons contained the spectinomycin-streptomycin resistance gene aadA1. Further characterization of the identified integrons revealed that many were part of the transposon Tn21, a genetic element that encodes both antibiotic resistance and heavy-metal resistance to mercuric compounds. Fifty percent of the clinical isolates positive for the integron marker gene intI1 as well as for theqacEΔ1 and aadA1 cassettes also contained the mercury reductase gene merA. The correlation between the presence of the merA gene with that of the integrase and antibiotic resistance genes suggests that these integrons are located in Tn21. The presence of these elements among avianE. coli isolates of diverse genetic makeup as well as inSalmonella suggests the mobility of Tn21 among pathogens in humans as well as poultry.
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Shetty, Varsha Prakash, Carol Rodrigues, and Vijaya Kumar Deekshit. "Detection of Multidrug-Resistant Integrons Associated with Acinetobacter baumannii Isolated from Clinical and Environmental Samples." Journal of Pure and Applied Microbiology 18, no. 1 (2024): 605–13. http://dx.doi.org/10.22207/jpam.18.1.44.
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The emergence of multidrug resistance (MDR) among pathogenic bacteria is a root cause of severe infections. It is threatening to observe that MDR is also found in ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) pathogens, which has caused a hike in nosocomial infection. The diminishing spectrum of treatment against these pathogens demands an alternative realm of treatment. One such nosocomial pathogen, Acinetobacter baumannii is known to cause pneumonia, blood stream infection, urinary tract infections, especially affecting immunocompromised individuals. Due to indiscriminate use of antibiotics, these pathogens have gained resistance to major classes of antibiotics through mutation and horizontal gene transfer via mobile genetic elements such as plasmids, transposons and integrons. This study mainly aims at identifying integron mediated drug resistance among clinical and environmental strains of A. baumannii. In this study, A. baumannii strains isolated from clinical and environmental samples were screened for antibiotic susceptibility tests. The multidrug resistant isolates were then checked for the presence of 3 classes of integrons viz Intl1 (Class 1), Intl2 (class 2) and, Intl3 (class 3). The integron region of the positive isolates was sequenced, and the drug-resistance gene cassettes were identified. All the clinical and environmental isolates were multidrug resistant. Three clinical isolates of A. baumannii showed positive amplification to Intl1 at 2kb, while none of the environmental isolates carried integrons, though they were multidrug resistant. The sequencing of the integron region of clinical isolates revealed the presence of three antibiotic resistance genes within the integron that encode resistance to chloramphenicol, rifampin, and aminoglycoside. This study prominently highlights the presence of class 1 integrons carrying different antimicrobial resistance determinants among A. baumannii isolated from clinical samples.
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KHAITSA, M. L., J. OLOYA, D. DOETKOTT, and R. KEGODE. "Antimicrobial Resistance and Association with Class 1 Integrons in Escherichia coli Isolated from Turkey Meat Products." Journal of Food Protection 71, no. 8 (2008): 1679–84. http://dx.doi.org/10.4315/0362-028x-71.8.1679.
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The objective of this study was to quantify the role of class 1 integrons in antimicrobial resistance in Escherichia coli isolated from turkey meat products purchased from retail outlets in the Midwestern United States. Of 242 E. coli isolates, 41.3% (102 of 242) tested positive for class 1 integrons. A significant association was shown between presence of class 1 integrons in E. coli isolates and the resistance to tetracycline, ampicillin, streptomycin, gentamicin, sulfisoxazole, and trimethoprim-sulfamethoxazole. Attributable risk analysis revealed that for every 100 E. coli isolates carrying class 1 integrons, resistance was demonstrated for ampicillin (22%), gentamycin (48%), streptomycin (29%), sulfisoxazole (40%), trimethoprimsulfamethoxazole (7%), and tetracycline (26%). Non–integron-related antimicrobial resistance was demonstrated for ampicillin (65%), gentamycin (16.9%), streptomycin (42.1%), sulfisoxazole (35.8%), and tetracycline (49.7%). Population-attributable fraction analysis showed that class 1 integrons accounted for the following resistances: gentamycin, 71% (50 of 71), amoxicillin–clavulanic acid, 19.6% (6 of 33), nalidixic acid, 34% (7 of 21), streptomycin, 28% (30 of 107), sulfisoxazole, 38% (40 of 106), and tetracycline, 14%, (26 of 185). In conclusion, although class 1 integrons have been implicated in resistance to antimicrobial agents, other non–integron resistance mechanisms seem to play an important part.
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Kim, Elizabeth, Nora Jean Nealon, Katherine A. Murray, Cydney Jardine, Roberta Magnuson, and Sangeeta Rao. "Integron-Mediated Antimicrobial Resistance and Virulence Factors in Salmonella Typhimurium Isolated from Poultry." Animals 14, no. 23 (2024): 3483. https://doi.org/10.3390/ani14233483.
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This study investigates antimicrobial-resistant (AMR) Salmonella Typhimurium in poultry, focusing on how class I integrons contribute to AMR and virulence. Using whole genome sequencing, researchers analyzed 26 S. Typhimurium isolates from U.S. poultry, finding that three isolates contained integrons (1000 base pairs each). These integron-positive isolates exhibited significantly higher resistance to beta-lactams, phenicols, and tetracyclines compared to integron-free isolates (p = 0.004, 0.009, and 0.02, respectively) and harbored genes like ges, imp, and oxa, which are linked to extended-spectrum beta-lactamase resistance. Most AMR gene classes (64%) were chromosome-based, with integron-positive isolates showing a broader array of resistance genes, including catB and tetA. Integron-bearing isolates had higher occurrences of bacteriocin genes and specific AMR genes like aminoglycoside and beta-lactam resistance genes, while integron-free isolates had more fimbrial and pilus genes. The presence of integrons may trend with increased AMR genes and virulence factors, highlighting the role of integron screening in enhancing AMR surveillance and reducing the need for high-priority antimicrobial treatments in poultry. These findings could support better AMR stewardship practices in poultry production, potentially lowering infection risks in humans and livestock.
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Ranjbar, Reza, Fatemeh Taghipour, Davoud Afshar, and Shohreh Farshad. "Distribution of Class 1 and 2 Integrons Among Salmonella Enterica Serovars Isolated from Iranian Patients." Open Microbiology Journal 13, no. 1 (2019): 63–66. http://dx.doi.org/10.2174/1874285801913010063.
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Background:Salmonella entericahas become increasingly resistant to antimicrobial agents, partly as a result of genes carried by integrons.Objective:The aim of the present study was to investigate the prevalence of class 1 and 2 integrons and resistance to antimicrobial agents in clinical isolates ofS. enterica.Methods:This study included allSalmonellaisolates, recovered from patients with salmonellosis, admitted to Medical Children Hospital, Tehran, Iran during 2015-2016. Bacterial isolates were identified using standard biochemical and agglutination tests. Antimicrobial susceptibility testing was performed according to the Clinical and Laboratory Standards Institute guidelines. The presence of class 1 and 2 integrons was investigated by Polymerase Chain Reaction (PCR) assay, using specific primers.Results:A total of 138Salmonellastrains were isolated and included in this study. Integrons were detected in 45 (32%) isolates. Class 1 and 2 integrons were detected in 24 (17.3%) and 21 (15.2%) isolates, respectively. All integron-positive isolates showed multidrug-resistant phenotypes. Resistance to more than three antimicrobial agents was observed in integron-positive isolates.Conclusions:Our findings showed that integrons were widely distributed amongS. entericaisolates in Tehran. Class 1 integrons are more prevalent than class 2 integrons inSalmonellaisolates, and there is an association with MDR patterns. Therefore, these integrons are more likely to be involved in the distribution of resistant phenotypes inSalmonellastrains.
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McDougall, Fiona, Wayne Boardman, Michael Gillings, and Michelle Power. "Bats as reservoirs of antibiotic resistance determinants: A survey of class 1 integrons in Grey-headed Flying Foxes (Pteropus poliocephalus)." Infection, Genetics and Evolution 70 (June 7, 2019): 107–13. https://doi.org/10.5281/zenodo.14817850.
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(Uploaded by Plazi for the Bat Literature Project) Increasing reports of antimicrobial resistance in wildlife highlight the significance of a One Health approach to managing resistance. We investigated the prevalence and diversity of class 1 integrons, a genetic determinant of resistance, in grey-headed flying foxes, a large fruit bat species belonging to the order Chiroptera. Class 1 integrons were detected in both wild flying foxes (5.3%) and captive flying foxes (41.2%) housed in wildlife rehabilitation facilities. Genes encoding resistance to aminoglycosides, trimethoprim and beta-lactams, and Qac efflux pumps were detected. Analysis of conserved integron elements and gene cassette arrays indicate the direction of integron transfer is from humans to flying foxes. The detection of two novel gene cassette arrays (5′CS-qacH-aacA34-blaOXA-21-3′CS and 5′CS-qacF-3′CS strongly suggests acquisition of genes from the environmental resistome into class 1 integrons within the flying fox microbiota. The dynamics of class 1 integrons in flying foxes indicates bats have a role in the emergence of novel antibiotic resistance determinants.
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Hasan, Asif Md Fuad, Anindita Bhowmik, Mohammad Nurul Islam, and Sunjukta Ahsan. "Validation of a Multiplex PCR for the Simultaneous Detection of E. coli and Class 1 Integron." Plant Tissue Culture and Biotechnology 33, no. 1 (2023): 17–24. http://dx.doi.org/10.3329/ptcb.v33i1.66063.
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Antibiotic resistant E. coli in the animal gut can promote the transfer of antibiotic resistance between animal and human. In order to enforce the National Action Plan in Bangladesh, it is imperative to detect the presence of E. coli harbouring Class 1 integrons that can potentially transfer antibiotic resistance genes among bacteria. Previously used primers pairs were used in a multiplex PCR to successfully detect the E. coli species-specific amplicon and Class 1 integron in 57% of the isolates. Plasmid was absent in the isolates. Antibiotic resistance profiling indicated highest resistance to oxytetracycline (89%) and lowest resistance to streptomycin (18.52%). A total of 38% isolates were found to be resistant against 8 of the 10 antibiotics used, 85.19% being multidrug resistant. However, the resistance pattern could not be specifically correlated to the presence of Class 1 integron. The validated multiplex PCR can be used as a quick method to detect E. coli and Class 1 integron simultaneously. Plant Tissue Cult. & Biotech. 33(1): 17-24, 2023 (June)
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TAHERIKALANI, MOROVAT, ABBAS MALEKI, NOURKHODA SADEGHIFARD, et al. "Dissemination of Class 1, 2 and 3 Integrons among Different Multidrug Resistant Isolates of Acinetobacter baumannii in Tehran Hospitals, Iran." Polish Journal of Microbiology 60, no. 2 (2011): 169–74. http://dx.doi.org/10.33073/pjm-2011-024.
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A total of 100 non-duplicate Acinetobacter baumannii isolates were collected from different hospitals in Tehran and were confirmed as A. baumannii by conventional biochemical and API testing. Antimicrobial susceptibility of these isolates was checked by a disk diffusion method in accordance with CLSI guidelines. The isolates were then detected as carrying class 1 and 2 integron gene cassettes by PCR evaluation and then genotyped by REP-PCR. More than 50% (n = 50) of the isolates were multidrug resistant. The results showed that more than 80% of all multidrug resistant A. baumannii strains carry a class 1 integron. Distribution of IntI 1 and IntI2 among A. baumannii isolates was 58% and 14%, respectively. Analysis of a conserved segment of class 1 integron showed a range from 100 bp to 2.5 kb. REP-PCR fingerprinting showed more than 20 genotypes among A. baumannii strains. TIhere was no relationship between REP genotypes and the distribution of different classes of integrons. This is a comprehensive study on the distribution of different classes of integrons among A. baumannii in Iran. Considering the exact role of integrons in coding drug resistance in bacteria, the findings of this study could help us find antimicrobial resistant mechanisms among A. baumannii isolates in Iran.
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Hansson, Karin, Lars Sundström, Alex Pelletier, and Paul H. Roy. "IntI2 Integron Integrase in Tn7." Journal of Bacteriology 184, no. 6 (2002): 1712–21. http://dx.doi.org/10.1128/jb.184.6.1712-1721.2002.
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ABSTRACT Integrons can insert and excise antibiotic resistance genes on plasmids in bacteria by site-specific recombination. Class 1 integrons code for an integrase, IntI1 (337 amino acids in length), and are generally borne on elements derived from Tn5090, such as that found in the central part of Tn21. A second class of integron is found on transposon Tn7 and its relatives. We have completed the sequence of the Tn7 integrase gene, intI2, which contains an internal stop codon. This codon was found to be conserved among intI2 genes on three other Tn7-like transposons harboring different cassettes. The predicted peptide sequence (IntI2*) is 325 amino acids long and is 46% identical to IntI1. In order to detect recombination activity, the internal stop codon at position 179 in the parental allele was changed to a triplet coding for glutamic acid. The sequences flanking the cassette arrays in the class 1 and 2 integrons are not closely related, but a common pool of mobile cassettes is used by the different integron classes; two of the three antibiotic resistance cassettes on Tn7 and its close relatives are also found in various class 1 integrons. We also observed a fourth excisable cassette downstream of those described previously in Tn7. The fourth cassette encodes a 165-amino-acid protein of unknown function with 6.5 contiguous repeats of a sequence coding for 7 amino acids. IntI2*179E promoted site-specific excision of each of the cassettes in Tn7 at different frequencies. The integrases from Tn21 and Tn7 showed limited cross-specificity in that IntI1 could excise all cassettes from both Tn21 and Tn7. However, we did not observe a corresponding excision of the aadA1 cassette from Tn21 by IntI2*179E.
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Zuberi, Zavuga, and Albert Joseph Sillo. "Antibiotic Resistance Conferred by Class 1 Integron in Vibrio Cholerae Strains: A Meta-analysis." East African Health Research Journal 6, no. 2 (2022): 119–26. http://dx.doi.org/10.24248/eahrj.v6i2.690.
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Background: Class 1 integron is the most ubiquitous platform among antibiotic resistance bacterial populations, including Vibrio cholerae strains. This meta-analysis aimed to determine the antibiotic resistance conferred by class 1 integron conserved segments (CS); 3’-qacEΔ1 and sul1, and 5’-int1 in V. cholerae strains. Methods: An intensive literature search of electronic databases for relevant studies from their starting dates up to April 2019 was conducted by two independent investigators. The electronic databases included; PubMed, Ovid Medline and Google Scholar databases. Only studies that determined antibiotic resistance conferred by class 1 integron in V. cholerae strains isolated from clinical and/or environmental samples using Polymerase Chain Reaction (PCR) assay were included in this study. Results: The random-effects model was selected and performed for all the studies included in this meta-analysis. Fourteen studies consisting of both qacEΔ1 and sul1, and int1 in the class 1 integron of V. cholerae strains were included. The proportions of class 1 integron 3’-CS and 5’-CS were 70.4 % (95%CI: 37.5–94.4) and 52 % (95% CI: 6.3–95.7) respectively. Conclusions: The proportions of class 1 integron in V. cholerae strains significantly contributed to the antibiotic resistances, which are comparable to other gram-negative bacteria clinical isolates. Moreover, the 3’-CS qacEΔ1 and sul1 are highly involved in the antibiotic resistance in comparison to 5’-CS int1. Generally, the study findings provide a general view on antibiotic resistance conferred by class 1 integron in Vibrio cholerae strains.
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Piekarska, Katarzyna, Katarzyna Zacharczuk, Magdalena Rzeczkowska, et al. "Probable Interspecies Transfer of the blaVIM-4 Gene between Enterobacter cloacae and Klebsiella pneumoniae in a Single Infant Patient." Polish Journal of Microbiology 64, no. 4 (2015): 387–89. http://dx.doi.org/10.5604/17331331.1185239.
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We report the interspecies transfer of the blaVIM-4 gene in MBL-producing Enterobacter cloacae and Klebsiella pneumoniae isolates from a newborn patient who had received meropenem therapy. We show evidence that gene blaVIM-4 was transmitted as a part of the class‑1 integron on a ca. ~90 kb conjugative plasmid. High homology of nucleotide sequence was observed between the integron found in VIM-4 producing E. cloacae and K. pneumoniae strains tested and class‑1 integrons previously reporteded in Pseudomonas aeruginosa from Hungary and Poland. This finding may suggest P. aeruginosa as a potential source of acquired VIM-4 in Enterobacteriaceae.
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Partridge, Sally R., Heidi J. Brown, H. W. Stokes, and Ruth M. Hall. "Transposons Tn1696 and Tn21and Their Integrons In4 and In2 Have Independent Origins." Antimicrobial Agents and Chemotherapy 45, no. 4 (2001): 1263–70. http://dx.doi.org/10.1128/aac.45.4.1263-1270.2001.
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ABSTRACT The first 13.6 kb of the mercury and multidrug resistance transposon Tn1696, which includes the class 1 integron In4, has been sequenced. In4 is 8.33 kb long and contains the 5′-conserved segment (5′-CS) and 2.24 kb of the 3′-conserved segment (3′-CS) flanking four integrated cassettes. The 3′-CS region is followed by one full copy and an adjacent partial copy of the insertion sequence IS6100 flanked, in inverse orientation, by two short segments (123 and 152 bp) from the outer right-hand end of class 1 integrons. This structure is representative of a distinct group of class 1 integrons that differs from In2, found in Tn21, and other related class 1 integrons. In4 does not include transposition genes but is bounded by characteristic 25-bp inverted repeats and flanked by a direct duplication of 5 bp of the target sequence, indicating that it was inserted by a transpositional mechanism. In4 lies between the resII and resIsites of a backbone mercury resistance transposon which is >99.5% identical to Tn5036. Although Tn21 and Tn1696 are both classified as members of the Tn21 subfamily of the Tn3 transposon family, the backbone mercury resistance transposons are only 79 to 96% identical. Tn21 also contains a region of about 0.7 kb not found in Tn1696. The integrons In2 and In4 carrying the antibiotic resistance genes have been inserted at different locations into distinct ancestral mercury resistance transposons. Thus, Tn21 and Tn1696 have independent histories and origins. Other transposons (Tn1403 and Tn1412) that include a class 1 integron also have independent origins. In all except Tn21, the integron is located within theres region of the backbone transposon.
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Baltazar-Cruz, Jesús, Rogelio Rojas-Rios, Violeta Larios-Serrato, Itza Mendoza-Sanchez, Everardo Curiel-Quesada, and Abigail Pérez-Valdespino. "A Class 4-like Chromosomal Integron Found in Aeromonas sp. Genomospecies paramedia Isolated from Human Feces." Microorganisms 11, no. 10 (2023): 2548. http://dx.doi.org/10.3390/microorganisms11102548.
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Integrons are genetic elements that store, express and exchange gene cassettes. These elements are characterized by containing a gene that codes for an integrase (intI), a cassette integration site (attI) and a variable region holding the cassettes. Using bioinformatics and molecular biology methods, a functional integron found in Aeromonas sp. 3925, a strain isolated from diarrheal stools, is described. To confirm the integron class, a phylogenetic analysis with amino acid sequences was conducted. The integrase was associated to class 4 integrases; however, it is clearly different from them. Thus, we classified the associated element as a class 4-like integron. We found that the integrase activity is not under the control of the SOS or catabolic repression, since the expression was not increased in the presence of mitomycin or arabinose. The class-4-like integron is located on the chromosome and contains two well-defined gene cassettes: aadA1 that confers resistance to streptomycin and lpt coding for a lipoprotein. It also includes eight Open Reading frames (ORFs) with unknown functions. The strain was characterized through a Multilocus Phylogenetic Analyses (MLPA) of the gyrB, gyrA, rpoD, recA, dnaJ and dnaX genes. The phylogenetic results grouped it into a different clade from the species already reported, making it impossible to assign a species. We resorted to undertaking complete genome sequencing and a phylogenomic analysis. Aeromonas sp. 3925 is related to A. media and A. rivipollensis clusters, but it is clearly different from these species. In silico DNA-DNA hybridization (isDDH) and Average Nucleotide Identity (ANI) analyses suggested that this isolate belongs to the genomospecies paramedia. This paper describes the first class 4-like integron in Aeromonas and contributes to the establishment of genomospecies paramedia.
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Levings, Renee S., Steven P. Djordjevic, and Ruth M. Hall. "SGI2, a Relative of Salmonella Genomic Island SGI1 with an Independent Origin." Antimicrobial Agents and Chemotherapy 52, no. 7 (2008): 2529–37. http://dx.doi.org/10.1128/aac.00189-08.
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ABSTRACT Multiply antibiotic-resistant Salmonella enterica serovar Emek strains isolated in Australia and the United Kingdom had similar features, suggesting that they all belong to a single clone. These strains all contain SGI2 (formerly SGI1-J), an independently formed relative of Salmonella genomic island SGI1. In SGI2, the complex class 1 integron which includes all of the resistance genes is not located between tnpR (S027) and S044 as in SGI1 and SGI1 variants. Instead, tnpR was found to be adjacent to S044, and the integron is located 6.9 kb away, within S023. In both SGI1 and SGI2, the 25-bp inverted repeats that mark the outer ends of class 1 integrons are flanked by a 5-bp duplication of the target, indicating that incorporation of the integron was by transposition. A small number of differences between the sequences of the backbones of SGI1 and SGI2 were also found. Hence, a class 1 integron has entered two different variants of the SGI backbone to generate two distinct lineages. Despite this, the integron in SGI2 has a complex structure that is very similar to that of In104 in SGI1. Differences are in the cassette arrays and in the gene which encodes the chloramphenicol and florfenicol efflux protein. The CmlA9 protein, encoded by InEmek, is only 92.8% identical to FloRc (also a CmlA family protein) from SGI1. A variant form of SGI2, SGI2-A, which has lost the tet(G) and cmlA9 resistance determinants, was found in one strain.
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Najibi, S., B. Bakhshi, S. Fallahzad, et al. "Distribution of class 1 integrons among enteropathogenic Escherichia coli." Canadian Journal of Microbiology 58, no. 5 (2012): 637–43. http://dx.doi.org/10.1139/w2012-035.
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The aim of this study was to investigate the incidence of and resistance gene content of class 1 integrons among enteropathogenic Escherichia coli (EPEC) and non-EPEC and to investigate intraspecies genetic diversity of EPEC strains isolated from children with diarrhea in Iran. Twenty-eight EPEC and 16 non-EPEC strains isolated from children with diarrhea were tested for the presence of a class 1 integron associated integrase gene (int1). Sequence analysis was performed to identify the resistance gene content of integrons. Genetic diversity and cluster analysis of EPEC isolates were also investigated using enterobacterial repetitive intergenic concensus – polymerase chain reaction (ERIC–PCR) fingerprinting. Twenty-three (82%) EPEC isolates and 11 (68.7%) non-EPEC isolates harbored the int1 gene specific to the conserved integrase region of class 1 integrons. Sequence analysis revealed the dominance of dfrA and aadA gene cassettes among the isolates of both groups. ERIC–PCR fingerprinting of EPEC isolates revealed a high diversity among these isolates. The widespread distribution of 2 resistance gene families (dfrA and aadA) among both groups of EPEC and non-EPEC isolates indicates the significance of integrons in antibiotic resistance transfer among these bacteria. Furthermore, clonal diversity of EPEC isolates harbouring a class 1 integron also suggests the circulation of these mobile elements among a diverse population of EPEC in this country.