Journal articles: 'Minimum inhibitory concentrations (MICs)'

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Branson, Edward. "Clinical relevance of Minimum Inhibitory Concentrations (MICs)." Aquaculture 196, no. 3-4 (May 2001): 289–96. http://dx.doi.org/10.1016/s0044-8486(01)00541-5.

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Pankuch, Glenn A., and Peter C. Appelbaum. "Activities of Tizoxanide and Nitazoxanide Compared to Those of Five Other Thiazolides and Three Other Agents against Anaerobic Species." Antimicrobial Agents and Chemotherapy 50, no. 3 (March 2006): 1112–17. http://dx.doi.org/10.1128/aac.50.3.1112-1117.2006.

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ABSTRACT Agar dilution was used, and MICs of metronidazole, tizoxanide, nitazoxanide, denitrotizoxanide, RM 4803, RM 4807, RM 4809, RM 4819, amoxicillin-clavulanate, and clindamycin were measured against 412 anaerobes. Nitazoxanide, tizoxanide, RM 4807, and RM 4809 were active against all groups, except for gram-positive non-spore-forming rods with 50% minimum inhibitory concentrations (when the latter were excluded) of 1 to 2 μg/ml and 90% minimum inhibitory concentrations of 4 to 8 μg/ml, respectively. Metronidazole MICs were usually lower against all groups except clostridia.

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Majoros, L., G. Kardos, B. Szabó, and M. Sipiczki. "Caspofungin Susceptibility Testing of Candida inconspicua: Correlation of Different Methods with the Minimal Fungicidal Concentration." Antimicrobial Agents and Chemotherapy 49, no. 8 (August 2005): 3486–88. http://dx.doi.org/10.1128/aac.49.8.3486-3488.2005.

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ABSTRACT Minimal inhibitory and minimal fungicidal concentrations of caspofungin were determined for 48 Candida inconspicua isolates. By using CLSI (formerly NCCLS) methodology with the partial inhibition endpoint criterion, caspofungin exhibited a good fungicidal effect against C. inconspicua (the MIC90 was 0.25 μg/ml and the minimum fungicidal concentration [MFC] was 0.5 μg/ml after 24 h). Total inhibition yielded falsely elevated MICs, exceeding even the respective MFCs.

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Kotani, Kenta, Mio Matsumura, Yuji Morita, Junko Tomida, Ryo Kutsuna, Kunihiko Nishino, Shuji Yasuike, and Yoshiaki Kawamura. "13-(2-Methylbenzyl) Berberine Is a More Potent Inhibitor of MexXY-Dependent Aminoglycoside Resistance than Berberine." Antibiotics 8, no. 4 (November 6, 2019): 212. http://dx.doi.org/10.3390/antibiotics8040212.

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We previously showed that berberine attenuates MexXY efflux-dependent aminoglycoside resistance in Pseudomonas aeruginosa. Here, we aimed to synthesize berberine derivatives with higher MexXY inhibitory activities. We synthesized 11 berberine derivatives, of which 13-(2-methylbenzyl) berberine (13-o-MBB) but not its regiomers showed the most promising MexXY inhibitory activity. 13-o-MBB reduced the minimum inhibitory concentrations (MICs) of various aminoglycosides 4- to 128 fold for a highly multidrug resistant P. aeruginosa strain. Moreover, 13-o-MBB significantly reduced the MICs of gentamicin and amikacin in Achromobacter xylosoxidans and Burkholderia cepacia. The fractional inhibitory concentration indices indicated that 13-o-MBB acted synergistically with aminoglycosides in only MexXY-positive P. aeruginosa strains. Time-kill curves showed that 13-o-MBB or higher concentrations of berberine increased the bactericidal activity of gentamicin by inhibiting MexXY in P. aeruginosa. Our findings indicate that 13-o-MBB inhibits MexXY-dependent aminoglycoside drug resistance more strongly than berberine and that 13-o-MBB is a useful inhibitor of aminoglycoside drug resistance due to MexXY.

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Bueno, Mírian Galvão, Elen Juliana Bonassa de Sousa, Juliana Hotta, Vinícius Carvalho Porto, Vanessa Migliorini Urban, and Karin Hermana Neppelenbroek. "Surface Properties of Temporary Soft Liners Modified by Minimum Inhibitory Concentrations of Antifungals." Brazilian Dental Journal 28, no. 2 (April 2017): 158–64. http://dx.doi.org/10.1590/0103-6440201701266.

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Abstract Evaluating the addition of minimum inhibitory concentrations (MICs) of antifungals for Candida albicans biofilm on the hardness and roughness of temporary denture soft liners. Specimens (n=8; 36×7×6 mm) of tissue conditioner (Softone) and resilient liner (Trusoft) were produced either without (control) or with incorporation of drugs at MICs: nystatin (0.032 g/mL), chlorhexidine diacetate (0.064 g/mL), ketoconazole (0.128 g/mL), miconazole (0.256 g/mL) and itraconazole (0.256 g/mL). Specimens were stored in distilled water at 37 °C for 24 h, 7 days and 14 days prior to the hardness/roughness measurements. Data were analyzed by 3-way ANOVA and Tukey HSD test (α=0.05). The addition of the antifungals into both materials demonstrated no evident hardness change or decrease of this property compared with the control, except for miconazole in Softone, which increased the hardness after 14 days (p=0.003). The addition of nystatin into both materials, chlorhexidine in Trusoft and ketoconazole in Softone resulted in no significant changes of roughness compared with the control, after 7 days and 14 days (p>0.05). In these periods, itraconazole increased the roughness of both materials (p<0.001). The addition of all antifungals, except for the miconazole in Softone, resulted in no deleterious effects on the materials’ hardness over the evaluation time. The MICs of nystatin in both temporary soft lining materials, ketoconazole in Softone and chlorhexidine in Trusoft resulted in no deleterious effects for roughness up to 14 days.

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Sandalakis, Vassilios, Dimosthenis Chochlakis, Ioannis Goniotakis, Yannis Tselentis, and Anna Psaroulaki. "Minimum inhibitory concentration distribution in environmental Legionella spp. isolates." Journal of Water and Health 12, no. 4 (April 16, 2014): 678–85. http://dx.doi.org/10.2166/wh.2014.217.

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In Greece standard tests are performed in the watering and cooling systems of hotels’ units either as part of the surveillance scheme or following human infection. The purpose of this study was to establish the minimum inhibitory concentration (MIC) distributions of environmental Legionella isolates for six antimicrobials commonly used for the treatment of Legionella infections, by MIC-test methodology. Water samples were collected from 2004 to 2011 from 124 hotels from the four prefectures of Crete (Greece). Sixty-eight (68) Legionella isolates, comprising L. pneumophila serogroups 1, 2, 3, 5, 6, 8, 12, 13, 15, L. anisa, L. rubrilucens, L. maceachernii, L. quinlivanii, L. oakridgensis, and L. taurinensis, were included in the study. MIC-tests were performed on buffered charcoal yeast extract with α-ketoglutarate, L-cysteine, and ferric pyrophosphate. The MICs were read after 2 days of incubation at 36 ± 1 °C at 2.5% CO2. A large distribution in MICs was recorded for each species and each antibiotic tested. Rifampicin proved to be the most potent antibiotic regardless of the Legionella spp.; tetracycline appeared to have the least activity on our environmental isolates. The MIC-test approach is an easy, although not so cost-effective, way to determine MICs in Legionella spp. These data should be kept in mind especially since these Legionella species may cause human disease.

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Galdiero, Emilia, Antonietta Siciliano, Renato Gesuele, Valeria Di Onofrio, Annarita Falanga, Angela Maione, Renato Liguori, Giovanni Libralato, and Marco Guida. "Melittin Inhibition and Eradication Activity for Resistant Polymicrobial Biofilm Isolated from a Dairy Industry after Disinfection." International Journal of Microbiology 2019 (January 15, 2019): 1–7. http://dx.doi.org/10.1155/2019/4012394.

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The emerging concern about the increase of antibiotic resistance and associated biofilm has encouraged scientists to look for alternative antibiotics such as antimicrobial peptides (AMPs). This study evaluated the ability of melittin to act as an antibacterial biofilm inhibitor and biofilm remover considering isolates from dairy industry. Minimum inhibitory concentrations (MICs), minimum bactericidal concentrations (MBCs), minimum biofilm inhibitory concentrations (MBICs), and biofilm removal activities were studied in polymicrobial biofilms produced from isolates. MIC and MBC were set at 1–3 µg/mL and 25–50 µg/mL for Gram-positive and Gram-negative bacteria, respectively. Results demonstrated a good MBIC reaching 85% inhibition ability and a good activity and better penetration in deeper layers against the mixed preformed biofilm, thereby increasing its activity against all isolates also at the lowest tested concentrations. Melittin showed interesting characteristics suggesting its potential to act as an antimicrobial agent for polymicrobial biofilm from dairy industry even in environmental isolates.

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Keepers, Tiffany R., Marcela Gomez, Donald Biek, Ian Critchley, and Kevin M. Krause. "Effect of In Vitro Testing Parameters on Ceftazidime-Avibactam Minimum Inhibitory Concentrations." International Scholarly Research Notices 2015 (May 19, 2015): 1–6. http://dx.doi.org/10.1155/2015/489547.

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Effects of varying in vitro susceptibility testing parameters of the broth microdilution assay on ceftazidime-avibactam MICs were determined and compared to meropenem and piperacillin-tazobactam for 9 Enterobacteriaceae and 4 Pseudomonas aeruginosa isolates. The effect of varying incubation conditions (ambient air or 5% CO2), pH of medium, medium composition (cation-adjusted Mueller Hinton Broth with and without laked horse blood and Haemophilus Test Medium), cation content of the medium, and inoculum density were tested. Most variations had no effect on ceftazidime-avibactam MIC values (no more than a 2-fold change). However, acidic pH or high inoculum resulted in 4- to 16-fold changes in MIC, which was similar to those observed for meropenem and piperacillin-tazobactam under these conditions. Overall, this study shows that slight variations in testing parameters during routine MIC testing will likely have no significant effect on ceftazidime-avibactam MIC values.

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Ip, Margaret, Shirley S. L. Chau, Sau Lai Lui, Eric Leung, and Thomas Ling. "Vancomycin minimum inhibitory concentrations (MICs) for meticillin-resistant Staphylococcus aureus (MRSA) in Hong Kong." International Journal of Antimicrobial Agents 36, no. 4 (October 2010): 386–87. http://dx.doi.org/10.1016/j.ijantimicag.2010.06.039.

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Stojkovic, D., Marina Sokovic, Jasmina Glamoclija, Ana Dzamic, M. Ristic, A. Fahal, Sami Khalid, Ivana Djuic, and Silvana Petrovic. "Susceptibility of three clinical isolates of Actinomodura madurae to α-pinene, the bioactive agent of Pinus pinaster turpentine oil." Archives of Biological Sciences 60, no. 4 (2008): 697–701. http://dx.doi.org/10.2298/abs0804697s.

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In vitro susceptibility of the turpentine oil obtained from Pinus pinaster oleoresin was evaluated against three Sudanese clinical isolates of Actinomadura madurae, which is the main causative agent of actinomycetoma. The minimum inhibitory concentrations (MICs) of the oil ranged from 100.3 to 124.8 ?L/mL, and the minimum microbicidal concentrations (MMCs) were between 100.3 and 150.0 ?L/mL. ?-Pinene exhibited prominent bioactivity with MICs ranging between 3.3 and 5.0 ?L/mL, while its MMC was 10.0 ?L/mL against the same clinical isolates. Pinus pinaster turpentine oil and ?-pinene might be useful agents in the treatment of mycetoma caused by A. madurae.

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Huang, Xueping, Yuan Liu, Zhihui Lin, Baihe Wu, Gaohui Nong, Yushan Chen, Yuping Lu, et al. "Minimum inhibitory concentrations of commonly used antibiotics against Helicobacter Pylori: A multicenter study in South China." PLOS ONE 16, no. 9 (September 2, 2021): e0256225. http://dx.doi.org/10.1371/journal.pone.0256225.

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Aim To determine the minimum inhibitory concentrations (MICs) of commonly used antibiotics against Helicobacter Pylori (H. pylori) in South China and compare their resistance rates by using EUCAST breakpoints and other breakpoints. Methods Patients who had not previously received H. pylori treatment in clinical centers in South China were enrolled in this study from 2017 to 2020. Gastric biopsies were obtained for H. pylori culture. The MICs of amoxicillin (AMX), clarithromycin (CLA), metronidazole (MTZ), levofloxacin (LEV), tetracycline (TET) and furazolidone (FZD) were tested by broth microdilution method and assessed by two different breakpoints. ATCC43504 standard strain served as a control. Results A total of 208 H. pylori strains were isolated from patients’ biopsy samples. The MICs of AMX, CLA, MTZ, LEV, TET and FZD for H. pylori were 0.0156-256mg/L (MIC50 0.125mg/L, MIC90 4mg/L), 0.0156- >256 mg/L (MIC50 0.0312mg/L, MIC90 64mg/L), 0.0156- >256mg/L (MIC50 8mg/L, MIC90 256mg/L), 0.0156-256mg/L (MIC50 0.25mg/L, MIC90 16mg/L), 0.0156-256mg/L (MIC50 0.0625mg/L, MIC90 4mg/L), and 0.0156- >256mg/L (MIC50 0.0312mg/L, MIC90 2mg/L), respectively. The MICs of AMX, CLA, MTZ, LEV, TET and FZD for ATCC43504 strain were 0.25mg/L, 0.0625mg/L, 64mg/L, 0.5mg/L, 1mg/L and 0.25mg/L, respectively. The resistance rate of FZD was 11.05%. The overall resistance rates according to EUCAST breakpoints and other breakpoints were 57.21% and 14.90% for AMX (p<0.001), 38.94% and 38.94% for CLA (p = 1), 39.42% and 50.96% for MTZ (p<0.001), 12.98% and 10.58% for TET (p = 0.025), 35.10% and 35.10% for LEV (p = 1), respectively. Conclusions Our results demonstrate that AMX, FZD, and TET, but not MTZ, CLR or LEV, showed good anti-H. pylori activity in vitro in South China. When different breakpoints were used, similar results were found with CLA, and LEV, but not with AMX, MTZ, or TET.

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Altshuler, Jerry, David J. Guervil, Charles D. Ericsson, Audrey Wanger, Samuel L. Aitken, and Luis Ostrosky-Zeichner. "Clinical Outcomes in Patients With Gram-Negative Infections Treated With Optimized Dosing Cefepime Over Various Minimum Inhibitory Concentrations." Journal of Pharmacy Practice 31, no. 1 (March 6, 2017): 34–39. http://dx.doi.org/10.1177/0897190017696950.

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Background: The Clinical and Laboratory Standards Institute (CLSI) revised cefepime interpretive criteria, introducing the susceptible dose-dependent category for Enterobacteriaceae with a minimum inhibitory concentration (MIC) of 4 to 8 μg/mL in 2014. Limited clinical data support these new categories. This study compares outcomes of patients treated with standard and high-dose cefepime across various MICs. Methods: We retrospectively reviewed cases of pneumonia or bacteremia caused by gram-negative organisms treated with adequate doses of cefepime for ≥48 hours. Outcomes were compared for MICs of ≤2 (low), 4 (medium), and 8 μg/mL (high). The primary end point was clinical failure, the secondary end point was microbiological failure. Results: Ninety cases met the inclusion criteria: 46, 25, and 19 patients with low, medium, or high MIC, respectively. Multivariate logistic regression revealed that the medium (odds ratio [OR]: 9.13, P < .01) and high (OR: 6.79, P = .01) MIC groups had increased clinical failure. Conclusion: Cefepime therapy, even at CLSI-recommended doses, had an increased risk of clinical failure for gram-negative pathogens with MICs of 4 or 8 μg/mL. This finding suggests that higher dosing regimens (2 g every 8 hours or 1 g every 6 hours) may be necessary to treat serious gram-negative infections with elevated MICs.

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Breierová, Emília, Ján Šajbidor, and Martin Lamačka. "The Influence of Newly Synthesised Fenpropimorph Derivatives on Some Pathogen Yeasts." Zeitschrift für Naturforschung C 56, no. 1-2 (February 1, 2001): 53–57. http://dx.doi.org/10.1515/znc-2001-1-210.

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Abstract The effect of minimum inhibitory concentrations (MICs) of six novel fenpropimorph derivatives on lipid and sterol composition of Candida albicans, Cryptococcus neoformans, Malassezia pachydermatis and Malassezia furfur was investigated. The MICs for the most effective derivatives were found in the range from 3.7 to 56.7 μм and were 2 -3 times lower compared to the commercial fungicide bifonazol. The more efficient fenpropimorph derivatives were the piperidine derivative for C. albicans and the allylamine derivative for Cr. neoformans, M. pachydermatis and M. furfur . The inhibitor in the growth medium reduced the unsaturation index of the total lipid content in M. furfur and C.

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Ho, Ming-Chih, Ching-Hsi Hsiao, Ming-Hui Sun, Yih-Shiou Hwang, Chi-Chun Lai, Wei-Chi Wu, and Kuan-Jen Chen. "Antimicrobial Susceptibility, Minimum Inhibitory Concentrations, and Clinical Profiles of Stenotrophomonas maltophilia Endophthalmitis." Microorganisms 9, no. 9 (August 30, 2021): 1840. http://dx.doi.org/10.3390/microorganisms9091840.

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Stenotrophomonas maltophilia has been reported in various ocular infections, including keratitis, conjunctivitis, preseptal cellulitis, and endophthalmitis, all of which may lead to vision loss. However, the S. maltophilia strain is resistant to a wide variety of antibiotics, including penicillins, third-generation cephalosporins, aminoglycosides, and imipenem. In this study, we retrospectively reviewed the clinical characteristics, antibiotic susceptibility, antimicrobial minimum inhibitory concentrations (MICs), and visual outcomes for S. maltophilia endophthalmitis. The data of 9 patients with positive S. maltophilia cultures in a tertiary referral center from 2010 to 2019 were reviewed. Cataract surgery (n = 8, 89%) was the most common etiology, followed by intravitreal injection (n = 1, 11%). S. maltophilia’s susceptibility to levofloxacin and moxifloxacin was observed in 6 cases (67%). Seven isolates were resistant to sulfamethoxazole-trimethoprim (78%). The MIC90 for S. maltophilia was 256, 256, 256, 8, 12, 12, 12, and 8 μg/mL for amikacin, cefuroxime, ceftazidime, tigecycline, sulfamethoxazole-trimethoprim, levofloxacin, galtifloxacin, and moxifloxacin, respectively. Final visual acuity was 20/200 or better in 5 patients (56%). Fluoroquinolones and tigecycline exhibited low antibiotic MIC90. Therefore, the results suggest that fluoroquinolones can be used as first-line antibiotics for S. maltophilia endophthalmitis.

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Kong, Lingti, Yan Tang, Xiaohua Zhang, Guoyu Lu, Meiling Yu, Qingping Shi, and Xiaofei Wu. "Pharmacokinetic/Pharmacodynamic Analysis of Meropenem for the Treatment of Nosocomial Pneumonia in Intracerebral Hemorrhage Patients by Monte Carlo Simulation." Annals of Pharmacotherapy 51, no. 11 (July 5, 2017): 970–75. http://dx.doi.org/10.1177/1060028017719715.

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Background: Nosocomial pneumonia (NP) is a frequent complication among patients with intracerebral hemorrhage (ICH). However, there are currently no pharmacokinetic (PK) and pharmacodynamic (PD) data to guide meropenem dosing in these patients. Objective: To investigate the PK/PD properties of meropenem in these patients and whether the usual dosing regimens of meropenem (2-hour infusion, 1 g, every 8 hours) was suitable. Methods: A total of 11 patients with a diagnosis of ICH complicated with NP were selected in the emergency internal medicine and treated with a 1-g/2-hours extended infusion model. The plasma concentrations of meropenem were determined by high-performance liquid chromatography. PK parameters were estimated by plasma concentration versus time profile using WinNonlin software. The probability of target attainments (PTAs) of meropenem at different minimum inhibitory concentrations (MICs) based on percentage time that concentrations were above the minimum inhibitory concentration (%T>MIC) value were performed by Monte Carlo simulation. Results: The volume of distribution and total body clearance of meropenem were 55.55 L/kg and 22.89 L/h, respectively. Using 40%T>MIC, PTA was >90% at MICs ≤4 µg/mL. Using 80% or 100%T>MIC, PTA was >90% only at MICs ≤1 µg/mL. Conclusions: The PK/PD profile of dosing regimens tested will assist in selecting the appropriate meropenem regimens for these patients. At a target of 40%T>MIC, the usual dosing regimens can provide good coverage for pathogens with MICs of ≤4 µg/mL. However, when a higher target (80% or 100%) is desired for difficult-to-treat infections, larger doses, prolonged infusions, shorter intervals, and/or combination therapy may be required.

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Jin-Jiang, Huang, Lu Jin-Chun, Lu Min, Huang Qing-Shan, and Li Guo-Dong. "The Design and Construction of K11: A Novelα-Helical Antimicrobial Peptide." International Journal of Microbiology 2012 (2012): 1–6. http://dx.doi.org/10.1155/2012/764834.

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Amphipathicα-helical antimicrobial peptides comprise a class of broad-spectrum agents that are used against pathogens. We designed a series of antimicrobial peptides, CP-P (KWKSFIKKLTSKFLHLAKKF) and its derivatives, and determined their minimum inhibitory concentrations (MICs) againstPseudomonas aeruginosa, their minimum hemolytic concentrations (MHCs) for human erythrocytes, and the Therapeutic Index (MHC/MIC ratio). We selected the derivative peptide K11, which had the highest therapeutic index (320) among the tested peptides, to determine the MICs against Gram-positive and Gram-negative bacteria and 22 clinical isolates includingAcinetobacter baumannii, methicillin-resistantStaphylococcus aureus, Pseudomonas aeruginosa, Staphylococcus epidermidis,andKlebsiella pneumonia. K11 exhibited low MICs (less than 10 μg/mL) and broad-spectrum antimicrobial activity, especially against clinically isolated drug-resistant pathogens. Therefore, these results indicate that K11 is a promising candidate antimicrobial peptide for further studies.

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Che Omar, Siti Nurhadis, Janna Ong Abdullah, Khairul Anuar Khairoji, Sieo Chin Chin, and Muhajir Hamid. "Effects of Flower and Fruit Extracts ofMelastoma malabathricumLinn. on Growth of Pathogenic Bacteria:Listeria monocytogenes, Staphylococcus aureus, Escherichia coli,andSalmonella typhimurium." Evidence-Based Complementary and Alternative Medicine 2013 (2013): 1–11. http://dx.doi.org/10.1155/2013/459089.

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Melastoma malabathricumLinn. is a shrub that comes with beautiful pink or purple flowers and has berries-like fruits rich in anthocyanins. This study was carried out with the aim to evaluate the inhibitory activities of different concentrations of theM. malabathricumLinn. flower and fruit crude extracts againstListeria monocytogenesIMR L55,Staphylococcus aureusIMR S244,Escherichia coliIMR E30, andSalmonella typhimuriumIMR S100 using the disc diffusion method. The lowest concentrations of the extracts producing inhibition zones against the test microorganisms were used to determine their minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs). In addition, the growth ofListeria monocytogenesIMR L55 andStaphylococcus aureusIMR S244 grown in medium supplemented with the respective extracts at different temperatures (4°C, 25°C, and 37°C) and pHs (4, 6, 7, and 8) was determined.

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Roh, Junghyun, and Seungwon Shin. "Antifungal and Antioxidant Activities of the Essential Oil fromAngelica koreanaNakai." Evidence-Based Complementary and Alternative Medicine 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/398503.

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Purpose. The purpose of this study is to determine the antifungal and antioxidant activities of the essential oil fromAngelica koreana.Methods. Essential oil was obtained from the dried roots ofA. koreanaby steam distillation, and its composition was identified by gas chromatography and mass spectrometry (GC-MS). The minimal inhibitory concentrations (MICs) of the oil fraction and its main components were determined by broth dilution assay using common pathogenicAspergillusandTrichophytonspecies. The combined effects of the oils with itraconazole were evaluated using a checkerboard titer test. In addition, 1,1-diphenyl-2-picryl-hydrazil (DPPH) free radical scavenging, nitrite inhibition, and reducing power were determined to assess the antioxidant activity of this oil.Results. The essential oil fraction and its main components showed inhibitory activity against all of the tested fungi, with minimal inhibitory concentrations (MICs) of 250–1000 μg/mL. Furthermore, this oil exhibited synergism when combined with itraconazole.Conclusion. In the treatment of infections caused byAspergillusandTrichophytonspecies, combining itraconazole with eitherA. koreanaessential oil or its main components may reduce the minimum effective dose of itraconazole required and, thus, minimize its side effects. In addition, this oil is a promising source of natural antioxidant agents.

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Bottinelli, Marco, Marianna Merenda, Michele Gastaldelli, Micaela Picchi, Elisabetta Stefani, Robin A. J. Nicholas, and Salvatore Catania. "The pathogen Mycoplasma dispar Shows High Minimum Inhibitory Concentrations for Antimicrobials Commonly Used for Bovine Respiratory Disease." Antibiotics 9, no. 8 (July 29, 2020): 460. http://dx.doi.org/10.3390/antibiotics9080460.

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Mycoplasma dispar is an overlooked pathogen often involved in bovine respiratory disease (BRD), which affects cattle around the world. BRD results in lost production and high treatment and prevention costs. Additionally, chronic therapies with multiple antimicrobials may lead to antimicrobial resistance. Data on antimicrobial susceptibility to M. dispar is limited so minimum inhibitory concentrations (MIC) of a range of antimicrobials routinely used in BRD were evaluated using a broth microdilution technique for 41 M. dispar isolates collected in Italy between 2011–2019. While all isolates had low MIC values for florfenicol (<1 μg/mL), many showed high MIC values for erythromycin (MIC90 ≥8 μg/mL). Tilmicosin MIC values were higher (MIC50 = 32 μg/mL) than those for tylosin (MIC50 = 0.25 μg/mL). Seven isolates had high MIC values for lincomycin, tilmicosin and tylosin (≥32 μg/mL). More, alarmingly, results showed more than half the strains had high MICs for enrofloxacin, a member of the fluoroquinolone class considered critically important in human health. A time-dependent progressive drift of enrofloxacin MICs towards high-concentration values was observed, indicative of an on-going selection process among the isolates.

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Citron, Diane M., Yumi A. Warren, Kerin L. Tyrrell, and Ellie J. C. Goldstein. "Activity of Ceftaroline against Aerobic Gram-Positive and Gram-Negative Pathogens: Effect of Test Method Variability." ISRN Microbiology 2011 (November 17, 2011): 1–5. http://dx.doi.org/10.5402/2011/787290.

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Ceftaroline is a new cephalosporin with bactericidal activity against methicillin-resistant S. aureus (MRSA) as well as gram-negative pathogens. Variations of in vitro test conditions were found to affect ceftaroline activity, with 5% NaCl inhibiting growth and/or reducing the minimum inhibitory concentrations (MICs) for E. coli, K. pneumoniae, M. catarrhalis, H. influenzae, and streptococci, while an inoculum of 106 CFU/mL raised MICs of some E. coli, K. pneumoniae, and M. catarrhalis strains.

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Rahmi, Annisa, Erpan Roebiakto, and Leka Lutpiatina. "Potensi Ekstrak Rimpang Kencur (Kaempferia galanga L.) Menghambat Pertumbuhan Candida albicans." Medical Laboratory Technology Journal 2, no. 2 (December 31, 2016): 70. http://dx.doi.org/10.31964/mltj.v2i2.94.

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<p style="text-align: justify;">Candida albicans infection is the cause of candidiasis. Candidiasis treatment can be done with a variety of antifungal drugs, one of them is rhizome of kencur (Kaempferia galanga L.). The Rhizome of kencur is selected as a traditional medicine because it contains chemical compounds such as flavonoids, tannins, saponins and essential oil that serves as an antifungal. This study aimed to determine the minimal inhibitory and minimal killing power and also an influence of kencur rhizome extract on the growth of Candida albicans in vitro. This research was true experimental design with posttest only control group design with tube dilution method. Results of Minimal Inhibitory Concentrations (MICs) research showed there was no clarity at concentration of 20 mg/mL, 30 mg/mL, 40 mg/mL, and it shows clarity at concentration of 50 mg/mL and 60 mg/mL. Results of Minimum Bactericidal Concentrations (MBCs) showed the number of colonies at concentration of 20 mg/mL were 84 colonies, concentration of 30 mg/mL were 48 colonies, concentration of 40 mg/mL were 27 colonies, concentration of mg/mL were 12 colonies and concentration of 60 mg/mL were 0 colony. Based on linear regression test, the result showed significance value of 0.000 <ɑ = 0.05 so it can be concluded that there is a kencur rhizome extract influence on the growth of Candida albicans in vitro with minimal inhibitory concentrations is the concentration of 50 mg/mL and the minimal bactericidal concentrations 60 mg/mL. Further studies are required regarding kencur rhizome extract (Kaempferia galanga L.) in inhibiting and bactericidal microorganisms other than Candida albicans.

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Ozawa, Manao, Michiko Kawanishi, Mariko Uchiyama, Daisuke Mitsuya, Hitoshi Abo, Ryoji Koike, and Mayumi Kijima. "Correlation of minimum inhibitory concentrations between human and animal antimicrobials against Escherichia coli isolated from livestock." Journal of Veterinary Diagnostic Investigation 33, no. 4 (June 23, 2021): 744–48. http://dx.doi.org/10.1177/10406387211019718.

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We analyzed the correlation between minimum inhibitory concentrations (MICs) of antimicrobials used in humans and those used in animals to enable comparison of antimicrobial susceptibility between Escherichia coli isolated from humans and those from animals. We compared the following pairs of MIC data: piperacillin (PIPC) to ampicillin (ABPC), amikacin (AMK) to kanamycin (KM), minocycline (MINO) to oxytetracycline (OTC), and levofloxacin (LVFX) to enrofloxacin (ERFX) using 103 isolates of E. coli from healthy livestock (cattle, pigs, broiler chickens, and layer chickens). Kappa analysis of the agreement for resistance and susceptibility between PIPC and ABPC, AMK and KM, MINO and OTC, and LVFX and ERFX showed almost perfect (κ = 0.81), slight (κ = 0.12), fair (κ = 0.37), and moderate (κ = 0.46) agreement, respectively. Within the antimicrobial pairs, all isolates resistant to the human antimicrobial were also resistant to the veterinary antimicrobial. However, there was less agreement within the pairs for those isolates that were sensitive to the human antimicrobial. The percentage agreement for susceptibility, defined as the percentage of isolates sensitive to both antimicrobials compared with isolates sensitive to both antimicrobials, as well as those sensitive only to the human antimicrobial, was 89.9%, 87.3%, 64.0%, and 89.9% for PIPC and ABPC, AMK and KM, MINO and OTC, and LVFX and ERFX, respectively. Our results suggest that the possibility of missing the resistance for antimicrobials used in human medicine by examining MICs for the equivalent antimicrobials used in veterinary medicine is low.

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Tran, Tien T. "Minimum inhibitory concentration (MIC) determination of herbal extracts against Escherichia coli, Salmonella Typhimurium, and Staphylococcus aureus." Journal of Agriculture and Development 17, no. 04 (August 28, 2018): 62–67. http://dx.doi.org/10.52997/jad.8.04.2018.

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The objective of this study was to determine the minimum inhibitoryconcentration (MIC) of crude extract from five medical herbs in Vietnam (Camellia sinensis, Eclipta prostrata L., Pseuderanthemum palatiferum, Psidium guajava, Azadirachta indica) against Escherichia coli ATCC25922, Salmonella Typhimurium, Staphylococcus aureus ATCC25923 by macro - dilution method. These results were the basis for the application of these herbs in the prevention and treatment of diseases in animals. The results showed that MICs of Camellia sinensis against E. coli, S. Typhimurium, and S. aureus were 8 - 16 mg/mL, 8 - 16 mg/mL, 0.5 mg/mL respectively; MICs of Eclipta prostrata L. against E. coli, S. Typhimurium, and S. aureus were 16 mg/mL, 16 mg/mL, 1 - 2 mg/mL respectively; MICs of Pseuderanthemum palatiferum against E. coli, S. Typhimurium and S. aureus were 8 mg/mL, 4 - 8 mg/mL, 2 - 4 mg/mL respectively; MICs of Psidium guajava against E. coli, S. Typhimurium and S. aureus were 16 mg/mL, 16 mg/mL, 0.125 - 0.25 mg/mL respectively and MICs of Azadirachta indica against E. coli, S. Typhimurium and S. aureus were more than 16 mg/mL.

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Machado, Denise Pires, Luciano Z. Goldani, Rodrigo Minuto Paiva, Valério Rodrigues Aquino, Fernanda de-Paris, Thiago Lisboa, Bruno Jung, and Rodrigo Pires dos Santos. "The Impact of Serum Vancomycin Levels and Minimum Inhibitory Concentrations of Methicillin-ResistantStaphylococcus aureuson Mortality in Patients with Nosocomial Pneumonia." Canadian Journal of Infectious Diseases and Medical Microbiology 24, no. 3 (2013): e75-e79. http://dx.doi.org/10.1155/2013/585834.

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BACKGROUND: Vancomycin is the treatment of choice for methicillin-resistantStaphylococcus aureus(MRSA) infections; however, treatment failure is not uncommon, even when the minimum inhibitory concentration (MIC) of the MRSA strain is within the susceptible range for vancomycin.OBJECTIVE: To describe the relationship between molecular markers such as themecAandagrIIgenes, serum vancomycin levels and vancomycin MICs, and the 30-day mortality rate of patients with nosocomial MRSA pneumonia in an intensive care unit (ICU).METHODS: The present study was a prospective cohort study including all patients with MRSA hospital-acquired pneumonia or ventilator-associated pneumonia who were admitted to the ICU of a tertiary care hospital between June 2009 and December 2011. The MIC for vancomycin was determined using the E-test and broth microdilution methods. Variables analyzed included age, sex, comorbid conditions, serum vancomycin trough concentration, the Acute Physiology and Chronic Health Evaluation II (APACHE) score and the presence of theagrIIgene. The primary outcome was mortality at 30 days.RESULTS: Thirty-six (42.4%) patients died within 30 days of the index MRSA culture. A multiple regression analysis that included the variables of MIC (determined using the E-test or broth microdilution methods), APACHE II score, serum vancomycin level and the presence ofagrIIrevealed that only the APACHE II score was related to the 30-day mortality rate (P=0.03). Seven patients (9.0%) with isolates exhibiting an MIC ≥1.5 μg/mL according to the E-test method died, and nine patients (11.6%) survived (P=0.76). Of the patients for whom MICs were determined using the broth microdilution method, 11 (14.1%) patients with MICs of 1.0 μg/mL died, and 16 (20.5%) survived (P=0.92). The median APACHE II score of survivors was 22.5, and the median score of nonsurvivors was 25.0 (P=0.03). The presence of theagrIIgene was not related to the 30-day mortality rate.CONCLUSIONS: Patients with severe hospital-acquired pneumonia presented with MRSA isolates with low to intermediate vancomycin MICs in the ICU setting. At theHospital de Clínicas de Porto Alegre(Porto Alegre, Brazil), the 30-day mortality rate was high, and was similar among patients with severe hospital-acquired pneumonia infected with MRSA isolates that exhibited MICs of ≤1.5 μg/mL determined using the E-test method and ≤1.0 μg/mL determined using the broth microdilution method in those who achieved optimal serum vancomycin levels. The APACHE II scores which provides an overall estimate of ICU mortality were independently associated with mortality in the present study, regardless of the MICs determined. Molecular markers, such as theagrIIgene, were not associated with higher mortality in the present study.

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Bloomgren, Brandon J., and Brad R. Laible. "Etest Versus Vitek 2 Vancomycin Minimum Inhibitory Concentration Testing Methods for Methicillin-Resistant Staphylococcus aureus." Journal of Pharmacy Practice 26, no. 4 (August 2013): 415–19. http://dx.doi.org/10.1177/0897190012466895.

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Purpose: To evaluate the discordance between Vitek 2 and Etest vancomycin minimum inhibitory concentration (MIC) testing methods in methicillin-resistant Staphylococcus aureus (MRSA) isolates. Methods: Inclusion criteria consisted of MRSA isolates with blood, respiratory, or wound origin of culture, inpatient or emergency department location at time of culture and isolates with a Vitek 2 MIC reported. Isolates were subjected to Etest and the resulting MICs were compared to the corresponding Vitek 2 MICs, and both the rate and degree of discordance were evaluated. Results: Seventy-five MRSA isolates met the inclusion criteria. Etest resulted in an MIC value greater than that of Vitek 2 in 64 isolates (85.3%). Furthermore, of the 35 isolates with an MIC of ≤0.5 mcg/mL via Vitek 2, Etest reported 27 isolates with an MIC >1 mcg/mL. Of the 39 isolates with a Vitek 2 MIC of 1 mcg/mL, Etest reported 30 isolates with an MIC >1 mcg/mL. Conclusion: We have demonstrated that Etest commonly reports MICs greater than 1 mcg/mL, even among isolates with MICs as low as ≤0.5 mcg/mL, according to Vitek 2. The clinical significance of these findings is unknown and would be an area of further study.

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Oluremi Adejoke Akinwale, Uyi Oluwatobi Emokpae, Opeyemi Mariam Adebogun, Morenike Olutumbi Adeoye-Isijola, and Olufunmiso Olusola Olajuyigbe. "In vitro effects of quinine on the antibacterial activity of erythromycin against bacteria of clinical relevance." GSC Biological and Pharmaceutical Sciences 14, no. 2 (February 28, 2021): 077–86. http://dx.doi.org/10.30574/gscbps.2021.14.2.0033.

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The study investigated the in vitro effects of quinine on the antibacterial activity of erythromycin for possible interactions. The antibacterial activities of each drug and their combinations were investigated by agar diffusion, agar and macrobroth dilution methods. While 100 µl of 1000 µg/ml of erythromycin produced inhibition zones ranging between 13 and 31 ± 1.0 mm in all the isolates except K. pneumoniae and P. aeruginosa ATCC 19582, combining the highest concentration of erythromycin with 35 µg/ml of quinine produced inhibition zones ranging between 14 and 34 ± 1.0 mm with the exception of S. flexneri KZN. Though quinine had no antibacterial effects on the isolates, erythromycin was effective at minimum inhibitory concentrations (MICs) ranging between 25 and 100 µg/ml while their combinations resulted in reduction of MICs of most of the isolates to 12.5 µg/ml except those against A. calcaoceuticus anitratus CSIR, Ps. aeruginosa ATCC 15442, P. shigelloides ATCC 51903, A. hydrophila ATCC 35654, Ps. aeruginosa ATCC 19582 and E. faecalis KZN that remained unchanged in agar dilution. While the MICs of erythromycin ranged between 25 and 50 µg/ml, the MICs of this antibiotic was reduced to concentrations ranging between 12.5 and 50 µg/ml indicating 50% to 75% in the presence of quinine. The combination of erythromycin and quinine, in vitro, resulted in synergistic (50%), additive/indifference (44.44%) and antagonistic (11.11%) interactions while quinine at concentrations lower than plasma quinine concentrations was inhibitory to the antibacterial activity of erythromycin. The synergistic effect may serve as remedy for bacterial infections in which the test bacteria have been implicated.

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Ismail, Che Ain Munirah, Zakuan Zainy Deris, Ruzilawati Abu Bakar, and Nabilah Ismail. "In Vitro Anti-Leptospiral Activity of Phyllanthus amarus Extracts and Their Combinations with Antibiotics." International Journal of Environmental Research and Public Health 18, no. 6 (March 10, 2021): 2834. http://dx.doi.org/10.3390/ijerph18062834.

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Despite modern medicine, there is an increasing trend for cases of the bacterial infection leptospirosis, and this has led to the exploration of alternative medicines from various sources including plants. The aim of this study was to investigate the in vitro anti-leptospiral activity of Phyllanthus amarus extracts alone and combined with penicillin G, ceftriaxone, and doxycycline. Antimicrobial susceptibility testing was performed using the microdilution broth technique upon methanol extract (ME), aqueous extract (AE), and antibiotics against the Leptospira interrogans serovars Australis, Bataviae, Canicola, and Javanica, to determine minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs). The results were analyzed using an ELISA microplate reader combined with microscopic analysis. Synergy testing using a checkerboard assay was performed to determine the fractional inhibitory concentration index values of extracts combined with antibiotics against leptospires. Scanning electron microscopy (SEM) was used to investigate morphological changes of leptospires caused by potential anti-leptospiral agents alone and combined with antibiotics. The MICs and MBCs for P. amarus extracts ranged from 100 to 400 µg/mL for AEs and from 400 to 800 µg/mL for MEs. Penicillin G was the most effective anti-leptospiral drug, with MICs and MBCs ranging from <0.01 to 0.78 and <0.01 to 3.13 µg/mL, respectively, followed by ceftriaxone, with both MICs and MBCs ranging from 0.05 to 0.78 µg/mL, and doxycycline, with MICs and MBCs ranging from 0.39 to 3.13 µg/mL and 12.5 to 25 µg/mL, respectively. Combinations of P. amarus extracts and antibiotics did not show synergistic effects on all tested Leptospira serovars, with some combinations demonstrating antagonistic effects. SEM analysis, however, showed distorted Leptospira surfaces. P. amarus AE performed better anti-leptospiral activity than P. amarus ME. The morphological effects of P. amarus extract alone and its combination with antibiotic on Leptospira cells revealed promising anti-leptospiral properties.

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Kazakova, Brunel, Khusnutdinova, Negrel, Giniyatullina, Lopatina, and Petrova. "A-Ring-Modified Triterpenoids and Their Spermidine–Aldimines with Strong Antibacterial Activity." Molbank 2019, no. 3 (September 6, 2019): M1078. http://dx.doi.org/10.3390/m1078.

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Synthesis of A-ring-modified lupane, oleanane and ursane type triterpenoid conjugates with spermidine through an aldimine linkage or diethylentriamine via an amide bond is described. These derivatives were evaluated for their in vitro antimicrobial properties against human pathogens. Except for derivatives 1 and 7, all compounds have moderate to weak minimum inhibitory concentrations (MICs) against Gram-positive Staphylococcus aureus bacteria, with MICs varying from 3.125 to 200 µM. Compound 11 is efficient against Escherichia coli and Pseudomonas aeruginosa, with MICs of 25 and 50 µM, respectively, while all other derivatives do not possess important antimicrobial activities against these Gram-negative bacteria.

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Vannice, Kirsten S., Jessica Ricaldi, Srinivas Nanduri, Ferric C. Fang, John B. Lynch, Chloe Bryson-Cahn, Theodore Wright, et al. "Streptococcus pyogenes pbp2x Mutation Confers Reduced Susceptibility to β-Lactam Antibiotics." Clinical Infectious Diseases 71, no. 1 (October 20, 2019): 201–4. http://dx.doi.org/10.1093/cid/ciz1000.

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Abstract Two near-identical clinical Streptococcus pyogenes isolates of emm subtype emm43.4 with a pbp2x missense mutation (T553K) were detected. Minimum inhibitory concentrations (MICs) for ampicillin and amoxicillin were 8-fold higher, and the MIC for cefotaxime was 3-fold higher than for near-isogenic control isolates, consistent with a first step in developing β-lactam resistance.

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Saleh, Basel, Razan Hammoud, and Ayman Al-Mariri. "Antimicrobial activity of Ficus sycomorus L. (Moraceae) leaf and stem-bark extracts against multidrug resistant human pathogens." Herba Polonica 61, no. 1 (March 1, 2015): 39–49. http://dx.doi.org/10.1515/hepo-2015-0009.

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Summary The present work was conducted to investigate antibacterial activity of methanol and acetone in leaf (LE) and stem-bark (SBE) of Ficus sycomorus L. crude extracts against sensitive and resistant species of Staphylococcus aureus and Acinetobacter baumannii pathogens. Antimicrobial activity expressed by disc-diffusion method (zone of inhibitions - ZIs), minimum inhibitory concentrations (MICs) and minimum bactericidal concentration (MBC) were measured as reported for many investigations. Similar study with 6 commercial antibiotics as a reference drug was undertaken. Based upon the estimated ZIs, MIC and MBC values, acetone LE exhibited higher antimicrobial activity than that of methanol one. Otherwise, standard antibiotics have lower effectiveness (ZIs, MICs and MBC) on all tested bacteria as compared to the SBE and LE. The highest antibacterial activity was recorded in sensitive A. baumannii isolate with MICs 2.5, 4.9 mg/ml and MBC 3.8, 9.7 mg/ml for acetone LE and SBE, respectively. Our data indicated that the lowest antibiotics antibacterial activity was recorded for resistant A. baumannii pathogen. It was lower than those of the both plant fractions extracts.

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Yang, Deng-Jye, Hsin-Yi Chen, and Shih-Chuan Liu. "Study of the Antibacterial Efficacy of Bainiku-Ekisu against Pathogens." International Journal of Bacteriology 2014 (October 28, 2014): 1–8. http://dx.doi.org/10.1155/2014/460395.

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The research was undertaken to determine the bacteriostatic effects of the concentrate of Japanese apricot juice (bainiku-ekisu), which is a popular health food in Taiwan and Japan, on Enterococcus faecalis ATCC 29212, Staphylococcus aureus ATCC 25923, and Escherichia coli ATCC 25922. The results show that E. faecalis, S. aureus, and E. coli could be killed or inhibited by bainiku-ekisu at concentrations between 1.0 and 10.0 mg/mL. The minimum inhibitory concentration (MIC) was 1 mg/mL for all strains, and the minimum bactericidal concentrations (MBCs) were 5, 2.5, and 2.5 mg/mL for E. faecalis, S. aureus, and E. coli, respectively. Using the growth rate to calculate the MICs and MBCs, the MICs were 1.55, 1.43, and 0.97 mg/mL, and the MBCs were 2.59, 2.63, and 2.25 mg/mL for E. faecalis, S. aureus, and E. coli, respectively. According to the D values, E. faecalis and S. aureus exhibited lower resistance than E. coli at lower bainiku-ekisu concentrations (1.0 and 2.5 mg/mL), and the resistance of these two pathogens was better than that of E. coli at higher bainiku-ekisu concentrations (5.0 and 10.0 mg/mL). The Z values of the E. faecalis, S. aureus, and E. coli strains were 3.47, 4.93, and 11.62 mg/mL, respectively.

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Woods, Robert J., Twisha S. Patel, Jerod L. Nagel, Duane W. Newton, and Andrew F. Read. "Institution-wide and Within-Patient Evolution of Daptomycin Susceptibility in Vancomycin-Resistant Enterococcus faecium Bloodstream Infections." Infection Control & Hospital Epidemiology 39, no. 2 (January 14, 2018): 226–28. http://dx.doi.org/10.1017/ice.2017.279.

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We report daptomycin minimum inhibitory concentrations (MICs) for vancomycin-resistant Enterococcus faecium isolated from bloodstream infections over a 4-year period. The daptomycin MIC increased over time hospital-wide for initial isolates and increased over time within patients, culminating in 40% of patients having daptomycin-nonsusceptible isolates in the final year of the study.Infect Control Hosp Epidemiol 2018;39:226–228

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Afagnigni, Alian Désiré, Maximilienne Ascension Nyegue, Janmeda Pracheta, Vinay Sharma, and François-Xavier Etoa. "The Ethanolic Leaf Extracts of Dissotis multiflora (Sm) Triana and Paullinia pinnata Linn Exert Inhibitory Effect on Escherichia coli Through Membrane Permeabilization, Loss of Intracellular Material, and DNA Fragmentation." Journal of Drug Delivery and Therapeutics 11, no. 2-S (April 15, 2021): 4–13. http://dx.doi.org/10.22270/jddt.v11i2-s.4774.

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Background: Dissotis multiflora (Sm) Triana and Paullinia pinnata Linn are widely used in Cameroonian traditional medicine to treat infectious diseases. These plants were found to be a reservoir of antioxidant and antimicrobial agents and have the potential to be used in clinic. Objective: To determine the mechanism of action of the ethanolic leaves extracts of Dissotis multiflora and Paullinia pinnata on Escherichia coli. Methodology: The microbroth dilution method was used to determine the minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs) of D. multiflora and P. pinnata ethanolic leaves extracts. The above samples were tested for their rate of killing of E. coli cells at 1 MIC and 2 MICs. Sorbitol protection, outer membrane permeability, loss of 260-nm-absorbing material, fluorescence microscopy, and DNA degradation assay were used to examine the ultrastructural changes in bacteria induced by the extracts. Results: D. multiflora and P. pinnata extracts inhibited bacterial growth with MICs of 390.62 and 781.25 µg/mL respectively, while the MBCs values were found to be 781.25 and 1562.5 µg/mL respectively. Treatment with extracts had shorter kill-time in a time-dependent manner with effect most pronounced at 2 MICs than 1 MIC. The MIC of D. multiflora increased 4x from 390.62 µg/mL after 24 h of incubation to 1562.5 µg/mL after 7 days in the presence of an osmoprotectant indicating the inhibition of synthesis of cell wall constituents. P. pinnata had no effect on cell wall. Both extracts exhibited the greatest leakage and release of DNA materials at 30, 60, 90, and 120 min in concentration-dependent manner. Treated groups had higher values than control. At low concentrations (1/2 MIC and 1 MIC), these extracts effectively permeate the intact outer membrane of Gram-negative bacteria. Both extract were implicated in DNA fragmentation. Moreover, fluorescent cells observed further confirmed its inhibitory effect against the tested pathogen. The antibacterial action involved disruption of membrane potential, increase of membrane permeabilization, leakage of cellular material, and death suggesting them to be an alternative to antibiotics. Conclusion: These findings contribute to the understanding of the antibacterial inhibitory effect of D. multiflora and P. pinnata.

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Richter, Sandra S., Patricia L. Winokur, Angela B. Brueggemann, Holly K. Huynh, Paul R. Rhomberg, Elizabeth M. Wingert, and Gary V. Doern. "Molecular Characterization of the β-Lactamases from Clinical Isolates of Moraxella (Branhamella)catarrhalis Obtained from 24 U.S. Medical Centers during 1994–1995 and 1997–1998." Antimicrobial Agents and Chemotherapy 44, no. 2 (February 1, 2000): 444–46. http://dx.doi.org/10.1128/aac.44.2.444-446.2000.

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ABSTRACT The β-lactamases from 403 Moraxella(Branhamella) catarrhalis clinical isolates obtained during 1994–1995 and 1997–1998 U.S. multicenter surveillance studies were characterized by isoelectric focusing. The overall prevalences of the BRO-1 and BRO-2 enzymes among β-lactamase-positive isolates were estimated to be 97.5 and 2.5%, respectively. The minimum inhibitory concentrations (MICs) of ampicillin for all BRO-2-producing isolates were ≤1 μg/ml; however, numerous β-lactamase-positive isolates for which the ampicillin MICs were ≤1 μg/ml produced the BRO-1 enzyme (88.1%).

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Alneyadi, Shaikha S., Anas A. Abdulqader, Alaa A. Salem, and Ibrahim M. Abdou. "Synthesis and antimicrobial activity of 4-trifluoromethylpyridine nucleosides." Heterocyclic Communications 23, no. 3 (June 27, 2017): 197–203. http://dx.doi.org/10.1515/hc-2017-0019.

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Abstract4-Trifluoromethylpyridine derivatives 4–8 represent good candidates for the discovery of new antibacterial agents. Fluorinated pyridine nucleosides 4–7 and non-nucleoside analogues 8a,b were synthesized and evaluated for their antibacterial activities against Staphylococcus aureus, Bacillus infantis, Escherichia coli and Stenotrophomonas maltophilia. The minimum inhibitory concentrations (MICs) of the new nucleosides 4–7 range from 1.3 to 4.9 μg/mL and MICs of fluoroaryl derivatives 8a,b are in the range of 1.8–5.5 μg/mL. Activity of amoxicillin, the reference drug, is 1.0–2.0 μg/mL under similar conditions.

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Chapnick, Edward K., Jeremy D. Gradon, Barry Kreiswirth, Larry I. Lutwick, Benjamin C. Schaffer, Thomas D. Schiano, and Michael H. Levi. "Comparative Killing Kinetics of Methicillin-Resistant Staphylococcus aureus by Bacitracin or Mupirocin." Infection Control & Hospital Epidemiology 17, no. 3 (March 1996): 178–80. http://dx.doi.org/10.1017/s0195941700006548.

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AbstractThe in vitro activities of bacitracin and mupirocin were compared for seven different strains of methicillin-resistant Staphylococcus aureus. Six of seven strains showed bacitracin minimum inhibitory concentrations (MICs) of 0.5 to 1.0 units/mL, and all seven had mupirocin MICs of 0.5 to 2 μg/mL. Time-kill studies revealed 2.6- to 4.5-log reduction in 24 hours with strains susceptible to bacitracin (4 units/mL) and 0 to 2.2 reduction with mupirocin (16 μg/mL). Bacitracin should be considered further for in vivo studies because of enhanced bacteriocidal effect and lower cost.

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Xie, Zhizhi, Changzhi Xu, Yanhua Yi, Donglin Zhu, and Yun Xi. "In Vitro Antibacterial Activity of Galla Chinensis Combined with Different Antibacterial Drugs against Carbapenem-Resistant E.Coli." Journal of Advances in Medicine Science 2, no. 4 (November 5, 2019): 15. http://dx.doi.org/10.30564/jams.v2i4.1229.

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Objective: To evaluate the antibacterial effects of meropenem and levofloxacin respectively combined with Galla chinensis on carbapenem-resistant Escherichia coli in vitro. Methods： The protocol was designed with checkerboard method and the carbapenem-resistant E.coli was isolated in our hospital. The minimum inhibitory concentrations(MICs) of G. chinensis alone and combined with 2 antimicrobial agents against carbapenem-resistant E.coli were determined by broth dilution method and the fractional inhibitory concentration index (FICI) was calculated according to MICs results. Result： the combined use of G. chinensis and meropenem (or levofloxacin) significantly decreased both MIC50 and MIC90; After the combination of G. chinensis and meropenem, the synergistic effect was 86.7%, and the additive effect was 13.3%, no irrelevant and antagonistic effects. After combined use of G. chinensis and levofloxacin, the synergistic effect was 66.7%, and the additive effect was 33.3%. No irrelevant and antagonistic effects. Conclusion： Galla chinensis combined with meropenem or levofloxacin has synergistic and additive antibacterial effect, with certain combined antibacterial activity.

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Dusane, Devendra H., Che O’May, and Nathalie Tufenkji. "Effect of tannic and gallic acids alone or in combination with carbenicillin or tetracycline on Chromobacterium violaceum CV026 growth, motility, and biofilm formation." Canadian Journal of Microbiology 61, no. 7 (July 2015): 487–94. http://dx.doi.org/10.1139/cjm-2015-0101.

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Chromobacterium violaceum is an opportunistic pathogen that causes infections that are difficult to treat. The goal of this research was to evaluate the effect of selected tannins (tannic acid (TA) and gallic acid (GA)) on bacterial growth, motility, antibiotic (carbenicillin, tetracycline) susceptibility, and biofilm formation. Both tannins, particularly TA, impaired bacterial growth levels and swimming motilities at sub-minimum inhibitory concentrations (sub-MICs). In combination with tannins, antibiotics showed increased MICs, suggesting that tannins interfered with antibacterial activity. Sub-MICs of tetracycline or TA alone enhanced biofilm formation of C. violaceum; however, in combination, these compounds inhibited biofilm formation. In contrast, carbenicillin at sub-MICs was effective in inhibiting C. violaceum biofilm formation; however, in combination with lower concentrations of TA or GA, biofilms were enhanced. These results provide insights into the effects of tannins on C. violaceum growth and their varying interaction with antibiotics used to target C. violaceum infections.

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Abdel-Massih, Roula, Elias Abdou, Elias Baydoun, and Ziad Daoud. "Antibacterial Activity of the Extracts Obtained from Rosmarinus officinalis, Origanum majorana, and Trigonella foenum-graecum on Highly Drug-Resistant Gram Negative Bacilli." Journal of Botany 2010 (November 7, 2010): 1–8. http://dx.doi.org/10.1155/2010/464087.

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Our aim was to determine the antimicrobial activity of three selected plants (Rosmarinus officinalis, Origanum majorana, and Trigonella foenum-graecum) against Extended Spectrum Beta Lactamase (ESBL)—producing Escherichia coli and Klebsiella pneumoniae— and to identify the specific plant fraction responsible for the antimicrobial activity. The plants were extracted with ethanol to yield the crude extract which was further subfractionated by different solvents to obtain the petroleum ether, the dichloromethane, the ethyl acetate, and the aqueous fractions. The Minimum Inhibitory Concentrations (MIC) and Minimum Bactericidal Concentrations (MBC) were determined using broth microdilution. The MICs ranged between 1.25 and 80 . The majority of these microorganisms were inhibited by 80 and 40 of the crude extracts. The petroleum ether fraction of Origanum majorana significantly inhibited 94% of the tested strains. Ethyl acetate extracts of all selected plants exhibited relatively low MICs and could be therefore described as strong antibacterial.

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Grass, Julian E., Shelley S. Magill, Isaac See, Uzma Ansari, Lucy E. Wilson, Elisabeth Vaeth, Paula Snippes Vagnone, et al. "Evaluation of Discrepancies in Carbapenem Minimum Inhibitory Concentrations Obtained at Clinical Laboratories Compared to a Public Health Laboratory." Infection Control & Hospital Epidemiology 41, S1 (October 2020): s474—s476. http://dx.doi.org/10.1017/ice.2020.1151.

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Background: Automated testing instruments (ATIs) are commonly used by clinical microbiology laboratories to perform antimicrobial susceptibility testing (AST), whereas public health laboratories may use established reference methods such as broth microdilution (BMD). We investigated discrepancies in carbapenem minimum inhibitory concentrations (MICs) among Enterobacteriaceae tested by clinical laboratory ATIs and by reference BMD at the CDC. Methods: During 2016–2018, we conducted laboratory- and population-based surveillance for carbapenem-resistant Enterobacteriaceae (CRE) through the CDC Emerging Infections Program (EIP) sites (10 sites by 2018). We defined an incident case as the first isolation of Enterobacter spp (E. cloacae complex or E. aerogenes), Escherichia coli, Klebsiella pneumoniae, K. oxytoca, or K. variicola resistant to doripenem, ertapenem, imipenem, or meropenem from normally sterile sites or urine identified from a resident of the EIP catchment area in a 30-day period. Cases had isolates that were determined to be carbapenem-resistant by clinical laboratory ATI MICs (MicroScan, BD Phoenix, or VITEK 2) or by other methods, using current Clinical and Laboratory Standards Institute (CLSI) criteria. A convenience sample of these isolates was tested by reference BMD at the CDC according to CLSI guidelines. Results: Overall, 1,787 isolates from 112 clinical laboratories were tested by BMD at the CDC. Of these, clinical laboratory ATI MIC results were available for 1,638 (91.7%); 855 (52.2%) from 71 clinical laboratories did not confirm as CRE at the CDC. Nonconfirming isolates were tested on either a MicroScan (235 of 462; 50.9%), BD Phoenix (249 of 411; 60.6%), or VITEK 2 (371 of 765; 48.5%). Lack of confirmation was most common among E. coli (62.2% of E. coli isolates tested) and Enterobacter spp (61.4% of Enterobacter isolates tested) (Fig. 1A), and among isolates testing resistant to ertapenem by the clinical laboratory ATI (52.1%, Fig. 1B). Of the 1,388 isolates resistant to ertapenem in the clinical laboratory, 1,006 (72.5%) were resistant only to ertapenem. Of the 855 nonconfirming isolates, 638 (74.6%) were resistant only to ertapenem based on clinical laboratory ATI MICs. Conclusions: Nonconfirming isolates were widespread across laboratories and ATIs. Lack of confirmation was most common among E. coli and Enterobacter spp. Among nonconfirming isolates, most were resistant only to ertapenem. These findings may suggest that ATIs overcall resistance to ertapenem or that isolate transport and storage conditions affect ertapenem resistance. Further investigation into this lack of confirmation is needed, and CRE case identification in public health surveillance may need to account for this phenomenon.Funding: NoneDisclosures: None

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Sayın, Selin. "Antimicrobial Activities of Some Marine Macroalgae Species from Iskenderun Bay." Turkish Journal of Agriculture - Food Science and Technology 9, no. 4 (April 25, 2021): 792–96. http://dx.doi.org/10.24925/turjaf.v9i4.792-796.4207.

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In the present study, the seaweeds belong to Phaeophyaceae (Halopteris scoparia (Linnaeus) Sauvageau 1904, Cystoseria mediterranea Sauvageau 1912), Rhodophaceae (Liagora viscida (Forsskål) C.Agardh 1822, Laurencia nidifica J.Agardh 1852) and Chlorophyceae (Enteromorpha multiramosa Bliding, nom. inval. 1960) collected from nearby Iskenderun-Turkey of Mediterranean Sea were detected for their antimicrobial activities against seven bacterial (Escherichia coli ATCC 35218, Bacillus cereus NRRL B-371, Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae ATCC 13883, Salmonella typhimurium ATCC 14028, Proteus vulgaris RSKK 96029) and three fungal strains (Candida albicans ATCC 10231, C. krusei ATCC 6258, C. tropicalis Y-12968). The antimicrobial activities were expressed as minimum inhibitory concentrations (MICs), minimum bacterial concentrations (MBCs) and minimum fungicidal concentrations (MFCs) were determined. According to the results obtained from MIC values of the extracts on pathogenic microorganisms were between 50 and 50 and

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Forsman, Lina Davies, Jerker Jonsson, Charlotta Wagrell, Jim Werngren, Mikael Mansjö, Maria Wijkander, Ramona Groenheit, et al. "Minimum Inhibitory Concentrations of Fluoroquinolones and Pyrazinamide Susceptibility Correlate to Clinical Improvement in Multidrug-resistant Tuberculosis Patients: A Nationwide Swedish Cohort Study Over 2 Decades." Clinical Infectious Diseases 69, no. 8 (December 18, 2018): 1394–402. http://dx.doi.org/10.1093/cid/ciy1068.

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Abstract Background Minimum inhibitory concentration (MIC) testing, unlike routine drug susceptibility testing (DST) at a single critical concentration, quantifies drug resistance. The association of MICs and treatment outcome in multidrug-resistant (MDR)–tuberculosis patients is unclear. Therefore, we correlated MICs of first- and second-line tuberculosis drugs with time to sputum culture conversion (tSCC) and treatment outcome in MDR-tuberculosis patients. Methods Clinical and demographic data of MDR-tuberculosis patients in Sweden, including DST results, were retrieved from medical records from 1992 to 2014. MIC determinations were performed retrospectively for the stored individual Mycobacterium tuberculosis (Mtb) isolates using broth microdilution in Middlebrook 7H9. We fitted Cox proportional hazard models correlating MICs, DST results, and clinical variables to tSCC and treatment outcome. Results Successful treatment outcome was observed in 83.5% (132/158) of MDR-tuberculosis patients. Increasing MICs of fluoroquinolones, diabetes, and age >40 years were significantly associated with unsuccessful treatment outcome. Patients treated with pyrazinamide (PZA) had a significantly shorter tSCC compared to patients who were not (median difference, 27 days). Conclusions Increasing MICs of fluoroquinolones were correlated with unsuccessful treatment outcome in MDR-tuberculosis patients. Further studies, including MIC testing and clinical outcome data to define clinical Mtb breakpoints, are warranted. PZA treatment was associated with shorter tSCC, highlighting the importance of PZA DST.

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Lasarte-Monterrubio, Cristina, Juan C. Vázquez-Ucha, Maria Maneiro, Jorge Arca-Suárez, Isaac Alonso, Paula Guijarro-Sánchez, John D. Buynak, Germán Bou, Concepción González-Bello, and Alejandro Beceiro. "Activity of Imipenem, Meropenem, Cefepime, and Sulbactam in Combination with the β-Lactamase Inhibitor LN-1-255 against Acinetobacter spp." Antibiotics 10, no. 2 (February 20, 2021): 210. http://dx.doi.org/10.3390/antibiotics10020210.

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Treatment of infections caused by Acinetobacter spp., particularly A. baumannii, is a major clinical problem due to its high rates of antibiotic resistance. New strategies must be developed; therefore, restoration of β-lactam efficacy through the use of β-lactamase inhibitors is paramount. Activities of the antibiotics imipenem, meropenem, cefepime, and sulbactam in combination with the penicillin-sulfone inhibitor LN-1-255 were tested by microdilution against 148 isolates of Acinetobacter spp. collected in 14 hospitals in Spain in 2020. Relevantly, the MIC90 (i.e., minimum concentration at which 90% of isolates were inhibited) of antibiotics in combination with LN-1-255 decreased 4- to 8-fold for all of the Acinetobacter isolates. Considering only the carbapenem-resistant A. baumannii isolates, which produce carbapenem-hydrolyzing class D β-lactamases, the addition of LN-1-255 decreased the resistance rates from 95.1% to 0% for imipenem, from 100% to 9.8% for meropenem, from 70.7% to 7.3% for cefepime, and sulbactam resistance rates from 9.8% to 0% and intermediate susceptibility rates from 53.7% to 2.4%. The inhibitor also decreased the minimum inhibitory concentrations (MICs) when tested against non-carbapenem-resistant Acinetobacter spp. isolates. In conclusion, combining LN-1-255 with imipenem, meropenem, cefepime, and sulbactam to target A. baumannii, and especially carbapenem-resistant isolates, represents an attractive option that should be developed for the treatment of infections caused by this pathogen.

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Chesdachai, Supavit, Radha Rajasingham, Melanie R. Nicol, David Meya, Felix Bongomin, Mahsa Abassi, Caleb Skipper, Richard Kwizera, Joshua Rhein, and David Boulware. "2120. Minimum Inhibitory Concentration Distribution of Fluconazole against Cryptococcus Species and the Fluconazole Exposure Prediction Model." Open Forum Infectious Diseases 6, Supplement_2 (October 2019): S717—S718. http://dx.doi.org/10.1093/ofid/ofz360.1800.

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Abstract Background Fluconazole is lifesaving for the treatment and prevention of cryptococcosis; however, optimal dosing is unknown. Initial fluconazole doses of 100 mg to 2000 mg/day have been used. Prevalence of fluconazole non-susceptible Cryptococcus is increasing over time, risking the efficacy of long-established standard dosing. Based on current minimum inhibitory concentration (MIC) distribution, we modeled fluconazole concentration and area under the curve (AUC) relative to MIC to propose a rational fluconazole dosing strategy. Methods First, we conducted a systematic review using the MEDLINE database for reports of fluconazole MIC distribution against clinical Cryptococcus isolates. Second, we utilized fluconazole concentrations from 92 Ugandans who received fluconazole 800 mg/day coupled with fluconazole’s known pharmacokinetics to predict plasma fluconazole concentrations for doses ranging from 100 mg to 2000 mg via linear regression. Third, the fluconazole AUC above MIC ratio were calculated using Monte Carlo simulation and using the MIC distribution elucidated during the systemic review. Results We summarized 21 studies with 11,094 clinical Cryptococcus isolates. MICs were normally distributed with geometric mean of 3.4 mg/mL, median (MIC50) of 4 mg/mL, and 90th percentile (MIC90) of 16 mg/mL. The median MIC50 trended upwards from 4 mg/mL in 2000–2012 to 8 mg/mL in 2014–2018. Predicted sub-therapeutic fluconazole concentrations (below MIC) would occur in 38% with 100 mg, 20% with 200 mg, and 8% with 400 mg. AUC/MIC ratio > 100 would occur in 53% for 400 mg, 74% for 800 mg, 84% for 1200 mg, and 88% for 1,600 mg. Conclusion Currently recommended fluconazole doses may be inadequate for cryptococcosis. Further clinical studies are needed for rational fluconazole dose selection. Disclosures All authors: No reported disclosures.

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Ma, Mingbiao, Mei Yuan, Ming Li, Xiaojuan Li, Hailin Huang, Haiping Wang, Jue Li, Tingyi Du, and Rongwei Huang. "Serotype Distribution and Characteristics of the Minimum Inhibitory Concentrations of Streptococcus pneumoniae Isolated from Pediatric Patients in Kunming, China." Current Microbiology 78, no. 3 (February 18, 2021): 954–60. http://dx.doi.org/10.1007/s00284-021-02365-4.

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AbstractStreptococcus pneumoniae (S. pneumoniae) is the main conditional pathogen of acute respiratory infection in infants, children, and older adults worldwide. It was great significant to identify the epidemic characteristics of serotypes and antibiotic susceptibility for the prevention and treatment of S. pneumoniae diseases. This research assessed the serotype distribution and the minimum inhibitory concentrations (MICs) of S. pneumoniae isolated from pediatric patients to provide information on the epidemiology and antibiotic resistance of S. pneumoniae in Kunming, China. A total of 140 S. pneumoniae isolates were collected from pediatric patients at Kunming Children’s Hospital from January 2016 to October 2017. Serotype identification was done by Quellung reaction and multiplex polymerase chain reaction. MICs were determined by E-test. 140 isolates distributed in 13 types of serotypes. The top-three prevalent serotypes were 19F, 19A, and 6B. The immunization coverage rate of 13-valent pneumococcal conjugate vaccine (PCV) was relatively higher and should be introduced into the vaccination program in the region. MIC50 of penicillin, ceftriaxone, and levofloxacin was 1 μg/mL. MIC50 for meropenem and vancomycin was 0.38 μg/mL. MIC90 of penicillin, ceftriaxone, and levofloxacin was 1.5 μg/mL and that of meropenem and vancomycin was 0.5 μg/mL. The MIC90 of erythromycin was > 256 μg/mL. In summary, S. pneumoniae had low resistance rates to penicillin, ceftriaxone, levofloxacin, vancomycin, and meropenem, and these antibiotics could be the first-line agents for children with pneumococcal infections in Kunming.

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Clothier, Kristin A., Joann M. Kinyon, Timothy S. Frana, Nadine Naberhaus, Leslie Bower, Erin L. Strait, and Kent Schwartz. "Species characterization and minimum inhibitory concentration patterns of Brachyspira species isolates from swine with clinical disease." Journal of Veterinary Diagnostic Investigation 23, no. 6 (November 2011): 1140–45. http://dx.doi.org/10.1177/1040638711425580.

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Typhlocolitis and dysentery due to Brachyspira hyodysenteriae infection represent an economically important disease syndrome in growing pigs. Largely disappearing from U.S. swine herds in the late 1990s and early 2000s, Brachyspira-associated disease and bacterial isolation from swine with clinical disease has increased in the last several years, and non– B. hyodysenteriae isolates are commonly identified. Antimicrobial resistance has been demonstrated in Brachyspira spp. isolates from Europe and Asia, and may be the reason for the resurgence in U.S. herds. Seventy-nine clinical isolates identified at the Iowa State University Veterinary Diagnostic Lab were tested with multiple polymerase chain reaction assays to establish species identity, and evaluated for minimum inhibitory concentrations (MICs) using an agar dilution method against lincomycin, gentamicin, valnemulin, tiamulin, salinomycin, and carbadox. Only 38.0% of isolates could be confirmed as the known pathogens B. hyodysenteriae (30.4%) or Brachyspira pilosicoli (7.6%). Twenty of the 79 isolates (25.3%) were identified as Brachyspira murdochii, and 13.9% could not be identified to species. The MIC values were consistently high against lincomycin and moderately high against gentamicin. The remaining antimicrobials had MICs that were at the low end of the test ranges. Brachyspira murdochii and Brachyspira spp. had significantly greater MIC values against several of these drugs than other Brachyspira spp. examined. The increased incidence of these less definitively characterized Brachyspira species with increased MIC values to commonly prescribed antimicrobials may, at least in part, explain the increased prevalence and severity of this disease complex in recent years. Further research is necessary to understand these changes.

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Wingler, Mary Joyce B., Darrell T. Childress, and Ricardo A. Maldonado. "Comparison of Vancomycin Treatment Failures for Methicillin-Resistant Staphylococcus aureus Bacteremia Stratified by Minimum Inhibitory Concentration." Journal of Pharmacy Technology 35, no. 5 (June 3, 2019): 203–7. http://dx.doi.org/10.1177/8755122519852679.

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Background: Optimal treatment of methicillin-resistant Staphylococcus aureus bacteremias (MRSABs) with vancomycin minimum inhibitory concentrations (MICs) high within the susceptible range is of concern due to the high rate of mortality and increased prevalence. Objective: The purpose of this study is to evaluate vancomycin treatment failures in patients with MRSAB stratified by vancomycin MIC. Methods: In this retrospective chart review, patients ≥19 years of age with MRSAB between July 2010 and December 2016 were included if they received intravenous vancomycin for ≥72 hours. Vancomycin treatment failures were compared between patients with vancomycin MICs of ≤1 mg/L and 2 mg/L. Vancomycin treatment failure was defined as microbiological failure at 7 days. Inpatient mortality, 30-day readmission, vancomycin-associated nephrotoxicity, and early bacteremia clearance at 48 to 96 hours were assessed as secondary endpoints. Results: Fifty-eight patients were included in the vancomycin MIC ≤1 mg/L group and 22 patients in the vancomycin MIC 2 mg/L group. No significant difference was found in vancomycin treatment failures at 7 days between groups (88% vs 91%, respectively; P = .850). At 96 hours, there was no significant difference in vancomycin treatment failures between groups (72% vs 90%, respectively; P = .127). No significant difference was found in mortality ( P > .99) or 30-day readmission ( P > .99). Conclusions: In this study, vancomycin treatment failures were not more prevalent in patients with vancomycin MIC of 2 mg/L at 7 days. Regardless of MIC, antibiotics should be switched to an alternative agent at 7 days for persistent bacteremia.

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Khan, Fazlurrahman, Panchanathan Manivasagan, Jang-Won Lee, Dung Pham, Junghwan Oh, and Young-Mog Kim. "Fucoidan-Stabilized Gold Nanoparticle-Mediated Biofilm Inhibition, Attenuation of Virulence and Motility Properties in Pseudomonas aeruginosa PAO1." Marine Drugs 17, no. 4 (April 3, 2019): 208. http://dx.doi.org/10.3390/md17040208.

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The emergence of antibiotic resistance in Pseudomonas aeruginosa due to biofilm formation has transformed this opportunistic pathogen into a life-threatening one. Biosynthesized nanoparticles are increasingly being recognized as an effective anti-biofilm strategy to counter P. aeruginosa biofilms. In the present study, gold nanoparticles (AuNPs) were biologically synthesized and stabilized using fucoidan, which is an active compound sourced from brown seaweed. Biosynthesized fucoidan-stabilized AuNPs (F-AuNPs) were subjected to characterization using UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), field emission transmission electron microscopy (FE-TEM), dynamic light scattering (DLS), and energy dispersive X-ray diffraction (EDX). The biosynthesized F-AuNPs were then evaluated for their inhibitory effects on P. aeruginosa bacterial growth, biofilm formation, virulence factor production, and bacterial motility. Overall, the activities of F-AuNPs towards P. aeruginosa were varied depending on their concentration. At minimum inhibitory concentration (MIC) (512 µg/mL) and at concentrations above MIC, F-AuNPs exerted antibacterial activity. In contrast, the sub-inhibitory concentration (sub-MIC) levels of F-AuNPs inhibited biofilm formation without affecting bacterial growth, and eradicated matured biofilm. The minimum biofilm inhibition concentration (MBIC) and minimum biofilm eradication concentration (MBEC) were identified as 128 µg/mL. Furthermore, sub-MICs of F-AuNPs also attenuated the production of several important virulence factors and impaired bacterial swarming, swimming, and twitching motilities. Findings from the present study provide important insights into the potential of F-AuNPs as an effective new drug for controlling P. aeruginosa-biofilm-related infections.

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Gupta, Sonal, Rakhi Bansal, Javed Ali, Reema Gabrani, and Shweta Dang. "Development and Characterization of Polyphenon 60 and Caffeine Microemulsion for Enhanced Antibacterial Activity." BioMed Research International 2014 (2014): 1–7. http://dx.doi.org/10.1155/2014/932017.

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Green tea catechins and caffeine have exhibited antibacterial activity; however, their use is limited by lack of stability and effective delivery systems. Polyphenon 60 (P60) and caffeine were encapsulated in a single microemulsion (ME) formulation with an objective to lower the minimum inhibitory concentrations (MICs) of the individual agents against selected pathogens (S. epidermidisandE. coli). Combination of two natural compounds would advocate two different mechanisms on the bacterial growth thereby providing for better antibacterial activity. Thermodynamically stable ME was developed and characterized with an average particle size of 17.58 nm, further confirmed by TEM analysis. Antibacterial studies included chequerboard microdilution assay to determine the MIC and fractional inhibitory concentration (FIC) of both the natural compounds individually and in combination. MIC and FIC results indicated that the combination of the above two natural compounds was proficient in lowering the MICs of individual agents. Results of DPPH assay indicated that ME system preserved the long term antioxidative potential of P60 and caffeine. The cytotoxicity of the optimized formulation on Vero cell line by MTT assay was found to be nontoxic to mammalian cells.

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Akinpelu, David A., Emmanuel O. Abioye, Olayinka A. Aiyegoro, Oluseun F. Akinpelu, and Anthony I. Okoh. "Evaluation of Antibacterial and Antifungal Properties ofAlchornea laxiflora(Benth.) Pax. & Hoffman." Evidence-Based Complementary and Alternative Medicine 2015 (2015): 1–6. http://dx.doi.org/10.1155/2015/684839.

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Alchornea laxifloraleaf extract was tested against a range of microorganisms using standard microbiological methods for antimicrobial activities. The extract inhibited the growth of all the bacterial and 15 fungal isolates tested. The zones of inhibition exhibited against the test bacteria ranged between 12 mm and 24 mm and between 11 mm and 24 mm for the extract and the antibiotic streptomycin, respectively. The zones of inhibition observed against the fungal isolates by the extract ranged between 12 mm and 23 mm. The minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs) exhibited by the extract against test bacteria ranged between 0.78 mg/mL–25 mg/mL and 1.56 mg/mL–25 mg/mL, respectively, while the MICs and minimum fungicidal concentrations (MFCs) values for the test fungi ranged between 8.75 mg/mL–35.00 mg/mL and 8.75 mg/mL–35.00 mg/L, respectively. The preliminary phytochemical screening of the extract revealed the presence of alkaloids, tannins, flavonoids, saponins, and reducing sugars as major phytoconstituents in the extract.A. laxifloraleaf extract is a potent source of antibacterial and antifungal compounds; further studies on the extract are ongoing in our laboratories to elucidate the probable mechanism(s) of action on bacteria and fungi found to be susceptible to the extract.

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Journal articles on the topic 'Minimum inhibitory concentrations (MICs)'

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