Academic literature on the topic 'Aliarcobacter'

Aliarcobacter butzleri is the most prevalent Aliarcobacter species and has been isolated from a wide variety of sources. This species is an emerging foodborne and zoonotic pathogen because the bacteria can be transmitted by contaminated food or water and can cause acute enteritis in humans. Currently, there is no database to identify antimicrobial/heavy metal resistance and virulence-associated genes specific for A. butzleri. The aim of this study was to investigate the antimicrobial susceptibility and resistance profile of two A. butzleri isolates from Muscovy ducks (Cairina moschata) reared on a water poultry farm in Thuringia, Germany, and to create a database to fill this capability gap. The taxonomic classification revealed that the isolates belong to the Aliarcobacter gen. nov. as A. butzleri comb. nov. The antibiotic susceptibility was determined using the gradient strip method. While one of the isolates was resistant to five antibiotics, the other isolate was resistant to only two antibiotics. The presence of antimicrobial/heavy metal resistance genes and virulence determinants was determined using two custom-made databases. The custom-made databases identified a large repertoire of potential resistance and virulence-associated genes. This study provides the first resistance and virulence determinants database for A. butzleri.

Aliarcobacter butzleri is an emergent enteropathogen that can be found in a range of environments. This bacterium presents a vast repertoire of efflux pumps, such as the ones belonging to the resistance nodulation cell division family, which may be associated with bacterial resistance, as well as virulence. Thus, this work aimed to evaluate the contribution of three RND efflux systems, AreABC, AreDEF and AreGHI, in the resistance and virulence of A. butzleri. Mutant strains were constructed by inactivation of the gene that encodes the inner membrane protein of these systems. The bacterial resistance profile of parental and mutant strains to several antimicrobials was assessed, as was the intracellular accumulation of the ethidium bromide dye. Regarding bacterial virulence, the role of these three efflux pumps on growth, strain fitness, motility, biofilm formation ability, survival in adverse conditions (oxidative stress and bile salts) and human serum and in vitro adhesion and invasion to Caco-2 cells was evaluated. We observed that the mutants from the three efflux pumps were more susceptible to several classes of antimicrobials than the parental strain and presented an increase in the accumulation of ethidium bromide, indicating a potential role of the efflux pumps in the extrusion of antimicrobials. The mutant strains had no bacterial growth defects; nonetheless, they presented a reduction in relative fitness. For the three mutants, an increase in the susceptibility to oxidative stress was observed, while only the mutant for AreGHI efflux pump showed a relevant role in bile stress survival. All the mutant strains showed an impairment in biofilm formation ability, were more susceptible to human serum and were less adherent to intestinal epithelial cells. Overall, the results support the contribution of the efflux pumps AreABC, AreDEF and AreGHI of A. butzleri to antimicrobial resistance, as well as to bacterial virulence.

Aliarcobacter butzleri is an emergent enteropathogen, showing high genetic diversity, which likely contributes to its adaptive capacity to different environments. Whether natural transformation can be a mechanism that generates genetic diversity in A. butzleri is still unknown. In the present study, we aimed to establish if A. butzleri is naturally competent for transformation and to investigate the factors influencing this process. Two different transformation procedures were tested using exogenous and isogenic DNA containing antibiotic resistance markers, and different external conditions influencing the process were evaluated. The highest number of transformable A. butzleri strains were obtained with the agar transformation method when compared to the biphasic system (65% versus 47%). A. butzleri was able to uptake isogenic chromosomal DNA at different growth phases, and the competence state was maintained from the exponential to the stationary phases. Overall, the optimal conditions for transformation with the biphasic system were the use of 1 μg of isogenic DNA and incubation at 30 °C under a microaerobic atmosphere, resulting in a transformation frequency ~8 × 10−6 transformants/CFU. We also observed that A. butzleri favored the transformation with the genetic material of its own strain/species, with the DNA incorporation process occurring promptly after the addition of genomic material. In addition, we observed that A. butzleri strains could exchange genetic material in co-culture assays. The presence of homologs of well-known genes involved in the competence in the A. butzleri genome corroborates the natural competence of this species. In conclusion, our results show that A. butzleri is a naturally transformable species, suggesting that horizontal gene transfer mediated by natural transformation is one of the processes contributing to its genetic diversity. In addition, natural transformation can be used as a tool for genetic studies of this species.

Aliarcobacter cibarius and Aliarcobacter thereius are two rarely detected Aliarcobacter species. In the study, we analyzed the antimicrobial susceptibility and provide detailed insights into the genotype and phylogeny of both species using whole-genome sequencing. Thermophilic Campylobacter species are the most common bacterial foodborne pathogens causing gastroenteritis in humans worldwide. The genus Aliarcobacter is part of the Campylobacteraceae family and includes the species Aliarcobacter butzleri, Aliarcobacter cryaerophilus, Aliarcobacter skirrowii, and the rarely described Aliarcobacter cibarius, Aliarcobacter faecis, Aliarcobacter lanthieri, Aliarcobacter thereius, and Acrobarter trophiarum. Aliarcobacter are emergent enteropathogens and potential zoonotic agents. Here, we generated, analyzed, and characterized whole-genome sequences of Aliarcobacter cibarius and Aliarcobacter thereius. They were isolated from water poultry farms in Germany, cultured and identified by MALDI-TOF MS. With PCR the identity was verified. Antibiotic susceptibility testing was carried out with erythromycin, ciprofloxacin, doxycycline, tetracycline, gentamicin, streptomycin, ampicillin, and cefotaxime using the gradient strip method (E-test). Whole-genome sequences were generated including those of reference strains. Complete genomes for six selected strains are reported. These provide detailed insights into the genotype. With these, we predicted in silico known AMR genes, virulence-associated genes, and plasmid replicons. Phenotypic analysis of resistance showed differences between the presence of resistance genes and the prediction of phenotypic resistance profiles. In Aliarcobacter butzleri, the nucleotide sequence of the gyrA gene (DQ464331) can show a signature mutation resulting in an amino acid change T85>I. Acrobarter cibarius and Acrobarter thereius showed the same gene as assessed by similarity annotation of the mutations 254C>G. Most of the isolates were found to be sensitive to ciprofloxacin. The ciprofloxacin-resistant Aliarcobacter thereius isolate was associated with the amino acid change T85>I. But this was not predicted with antibiotic resistance databases, before. Ultimately, a phylogenetic analysis was done to facilitate in future outbreak analysis.

Aliarcobacter butzleri is an emerging foodborne and zoonotic pathogen that is usually transmitted via contaminated food or water. A. butzleri is not only the most prevalent Aliarcobacter species, it is also closely related to thermophilic Campylobacter, which have shown increasing resistance in recent years. Therefore, it is important to assess its resistance and virulence profiles. In this study, 45 Aliarcobacter butzleri strains from water poultry farms in Thuringia, Germany, were subjected to an antimicrobial susceptibility test using the gradient strip diffusion method and whole-genome sequencing. In the phylogenetic analysis, the genomes of the German strains showed high genetic diversity. Thirty-three isolates formed 11 subgroups containing two to six strains. The antimicrobial susceptibility testing showed that 32 strains were resistant to erythromycin, 26 to doxycycline, and 20 to tetracycline, respectively. Only two strains were resistant to ciprofloxacin, while 39 strains were resistant to streptomycin. The in silico prediction of the antimicrobial resistance profiles identified a large repertoire of potential resistance mechanisms. A strong correlation between a gyrA point mutation (Thr-85-Ile) and ciprofloxacin resistance was found in 11 strains. A partial correlation was observed between the presence of the bla3 gene and ampicillin resistance. In silico virulence profiling revealed a broad spectrum of putative virulence factors, including a complete lipid A cluster in all studied genomes.

Aliarcobacter butzleri is an emergent enteropathogen for which resistance to several classes of antimicrobial agents has been described, although the underlying mechanisms have been poorly addressed. We aimed to evaluate the contribution of the resistance-nodulation-division-type (RND) efflux system, AreABC, to drug resistance in A. butzleri . A. butzleri strains were first tested against several antimicrobials with and without an efflux pump inhibitor.

Einleitung: Aliarcobacter (A.) cryaerophilus und Aliarcobacter butzleri gelten weltweit als lebensmittelbedingte und zoonotische Krankheitserreger, die vorrangig über kontaminierte Lebensmittel oder Trinkwasser übertragen werden. Beim Menschen stellt sich die Infektion meist als selbstlimitierende Enteritis dar, wohingegen sie bei Tieren neben gastrointestinalen Erkrankungen mit Mastitiden, Aborten und Reproduktionsstörungen assoziiert wird. Aufgrund der engen Verwandtschaft mit den thermophilen Campylobacter spp., deren antimikrobielle Resistenz in den letzten Jahren einen starken Anstieg verzeichnet, ist es wichtig, das Resistenz- und Virulenzprofil dieser beiden Spezies zu untersuchen. Ziel der Untersuchungen: Ziel dieser Arbeit war die Bestimmung der phänotypischen und genotypischen Antibiotikaresistenz sowie die Ermittlung der Virulenzprofile von Aliarcobacter cryaerophilus- und Aliarcobacter butzleri-Stämmen, die aus Kotproben von Wassergeflügel aus Thüringen isoliert worden waren. Tiere, Material und Methoden: In die Untersuchung gingen insgesamt 250 Kotproben von 135 Gänsen, 45 Flugenten, 40 Mularden und 30 Pekingenten ein, die in den Jahren 2016 und 2017 von zehn verschiedenen Wassergeflügel-Betrieben in Thüringen, Deutschland, gesammelt und auf Aliarcobacter spp. untersucht wurden. Die mit MALDI-TOF MS und multiplex-PCR identifizierten Aliarcobacter-Isolate wurden anschließend mithilfe des Epsilometertest (E-Test) auf ihre antimikrobielle Empfindlichkeit gegenüber acht verschiedenen Antibiotika getestet. Nach der DNA-Isolierung und Gesamtgenom-Sequenzierung wurde die phylogenetische Verwandtschaft sowie die Anwesenheit von potentiellen Resistenz- und Virulenzgenen mit Hilfe bioinformatischer Programme untersucht. Ergebnisse: Aus 55 Aliarcobacter-positiven Kotproben wurden mittels MALDI-TOF MS und multiplex-PCR 27 A. cryaerophilus- und 47 A. butzleri-Isolate identifiziert. Die hier untersuchten A. cryaerophilus-Stämme gehören dem Cluster I und somit dem Genomovar A. cryaerophilus gv. pseudocryaerophilus an. Zusätzlich wurde durch die phylogenetischen Untersuchungen deutlich, dass beide Aliarcobacter-Spezies eine hohe genetische Diversität aufweisen. Gleichzeitig bildeten einige A. cryaerophilus- und A. butzleri-Isolate Untergruppen. In diesen waren die einzelnen Bakterienstämme, welche zum Teil aus unterschiedlichen Betrieben stammten, nur wenige Einzelnukleotid-Polymorphismen (SNPs) voneinander entfernt. Die Bestimmung der phänotypischen antimikrobiellen Empfindlichkeit offenbarte, dass allen 74 Aliarcobacter-Isolaten die Cefotaxim-Resistenz gemein war. Ferner waren mehr als drei Viertel der Aliarcobacter-Stämme resistent gegen Streptomycin. Die 27 A. cryaerophilus-Stämme zeichneten sich durch eine Empfindlichkeit gegenüber Erythromycin, Gentamicin sowie Ampicillin und somit durch ein homogenes Resistenzprofil aus. Im Gegensatz dazu zeigten die 47 A. butzleri-Stämme ein heterogenes Resistenzprofil. Während die A. butzleri-Stämme eine deutlich höhere Resistenzrate gegenüber den Tetracyclinen aufwiesen, waren die A. cryaerophilus-Stämme vermehrt gegen Ciprofloxacin resistent. In beiden Aliarcobacter-Spezies wurde ein großes Arsenal an potentiellen Resistenzgenen identifiziert. Neben mehreren Effluxpumpen wurden verschiedene β-Laktamase-Gene sowie die bekannte Ciprofloxacin-Resistenz vermittelnde Punktmutation an Position 254 in der Chinolon-Resistenz-bestimmenden Region im gyrA-Gen detektiert. Des Weiteren wurde eine Vielzahl an potentiellen Virulenzgenen in beiden Aliarcobacter-Spezies ermittelt. Zum Repertoire gehören unter anderem ein komplettes Chemotaxis-System, ein Urease-Cluster, mehrere Flagellum-Gene sowie ein Lipid-A-Cluster. Schlussfolgerungen: Obwohl die untersuchten Isolate auf eine Region (Thüringen), einen bestimmten Wirtstyp (Wassergeflügel) und eine kurze Studienzeit (2 Jahre) begrenzt waren, deuten die Ergebnisse der vorliegenden Arbeit auf ein hohes Maß an genetischer Diversität unter den A. cryaerophilus- und A. butzleri-Stämmen hin. Dabei ist die Stammdiversität innerhalb beider Spezies unabhängig von der geographischen Lage, dem Ursprung der Isolate und der Wirtsart. Aliarcobacter-Isolate, die aus dem selben Betrieb stammen, wurden aufgrund ihrer klonalen Verwandtschaft der gleichen Untergruppe zugeordnet. Die Existenz phylogenetisch ähnlicher Stämme aus mehreren Betrieben, weist auf eine mögliche epidemiologische Verbindung zwischen den einzelnen Betrieben hin. Durch die Untersuchungen wurde deutlich, dass auf die Bestimmung der phänotypischen antimikrobiellen Empfindlichkeit zugunsten der genotypischen Resistenzbestimmung nicht verzichtet werden kann, da der Genotyp nur in einem beschränken Umfang mit der phänotypischen Charakterisierung übereinstimmt. Ein direkter Zusammenhang zwischen der Anwesenheit einer bekannten Mutation im gyrA-Gen und der phänotypischen Ciprofloxacin-Resistenz konnte nur bei den A. butzleri-Stämmen festgestellt werden. Die im Rahmen dieser Studie erstellte Resistenz- und Virulenzdatenbank, ermöglicht eine unkomplizierte Bestimmung des genotypischen Resistenz- und Virulenzprofiles von A. butzleri-Stämmen.