Dataset Information

Molecular characterization of beta-lactamase genes and their genetic structures in Acinetobacter genospecies 3 isolates in Taiwan.

ABSTRACT: The genetic structure of beta-lactamases in Acinetobacter genospecies 3 (AG3) isolates in Taiwan was studied to analyze their high rates of resistance to beta-lactams, including carbapenems (57.9%). bla(IMP-1) and bla(IMP-8) were located in a class 1 integron. bla(OXA-58) was bracketed by ISAba3. A novel TnpF-like integrase gene was identified upstream of bla(VEB-3). Adjacent to the 5' sequence of the bla(ADC) gene, folE was identified. Four new Acinetobacter-derived cephalosporinase (ADC) enzymes were found, which clustered phylogenetically with published AG3 ADC proteins.

SUBMITTER: Huang LY

PROVIDER: S-EPMC2876422 | biostudies-literature | 2010 Jun

REPOSITORIES: biostudies-literature

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Molecular characterization of beta-lactamase genes and their genetic structures in Acinetobacter genospecies 3 isolates in Taiwan.

Huang Li-Yueh LY Lu Po-Liang PL Chen Te-Li TL Chang Fang-Yee FY Fung Chang-Phone CP Siu L K LK

Antimicrobial agents and chemotherapy 20100405 6

The genetic structure of beta-lactamases in Acinetobacter genospecies 3 (AG3) isolates in Taiwan was studied to analyze their high rates of resistance to beta-lactams, including carbapenems (57.9%). bla(IMP-1) and bla(IMP-8) were located in a class 1 integron. bla(OXA-58) was bracketed by ISAba3. A novel TnpF-like integrase gene was identified upstream of bla(VEB-3). Adjacent to the 5' sequence of the bla(ADC) gene, folE was identified. Four new Acinetobacter-derived cephalosporinase (ADC) enzym ...[more]

PMID: 20368407

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Project description:BackgroundAcinetobacter baumannii is a nosocomial pathogen which is establishing as a major cause of morbidity and mortality within the healthcare community. The success of this pathogen is largely due to its ability to rapidly gain resistance to antimicrobial therapies and its capability to persist in an abiotic environment through the production of a biofilm. Our tertiary-care hospital has showed high incidence of carbapenem-resistant Acinetobacter baumannii (CRAB) isolates.MethodsIn this study we explore both genotypic and phenotypic properties of 26 CRAB isolates: 16 isolates were collected from January 2010 to March 2011, and 10 were collected between February and May 2015.ResultsWe determined that all 26 CRAB isolates possessed multiple β-lactamase genes, including genes from Groups A, C, and D. Specifically, 42% of the isolates possesses the potentially plasmid-borne genes of OXA-23-like or OXA-40-like β-lactamase. The presence of mobile gene element integron cassettes and/or integrases in 88% of the isolates suggests a possible mechanism of dissemination of antibiotic resistance genes. Additionally, the location of insertion sequence (IS) ISAba1 in promotor region of of the OXA-51-like, ADC-7, and ampC genes was confirmed. Multilocus sequence typing (MLST) demonstrated that all 26 CRAB isolates were either sequence type (ST)-229 or ST-2. Interestingly, ST-2 went from being the minority CRAB strain in the 2010-2011 isolates to the predominant strain in the 2015 isolates (from 32 to 90%). We show that the ST-2 strains have an enhanced ability to produce biofilms in comparison to the ST-229 strains, and this fact has potentially led to more successful colonization of the clinical environment over time.ConclusionsThis study provides a longitudinal genetic and phenotypic survey of two CRAB sequence types, and suggests how their differing phenotypes may interact with the selective pressures of a hospital setting effecting strain dominance over a 5-year period.

Project description:To investigate the efficacy of fosfomycin against extended-spectrum β-lactamases (ESBL) producing Escherichia coli in Taiwan and the resistance mechanisms and characterization of human and pig isolates, we analyzed 145 ESBL-producing isolates collected from two hospitals (n = 123) and five farms (n = 22) in Taiwan from February to May, 2013. Antimicrobial susceptibilities were determined. Clonal relatedness was determined by PFGE and multi-locus sequence typing. ESBLs, ampC, and fosfomycin resistant genes were detected by PCR, and their flanking regions were determined by PCR mapping and sequencing. The fosfomycin resistant mechanisms, including modification of the antibiotic target (MurA), functionless transporters (GlpT and UhpT) and their regulating genes such as uhpA, cyaA, and ptsI, and antibiotic inactivation by enzymes (FosA and FosC), were examined. The size and replicon type of plasmids carrying fosfomycin resistant genes were analyzed. Our results revealed the susceptibility rates of fosfomycin were 94% for human ESBL-producing E. coli isolates and 77% for pig isolates. The PFGE analysis revealed 79 pulsotypes. No pulsotype was found existing in both human and pig isolates. Three pulsotypes were distributed among isolates from two hospitals. ISEcp1 carrying blaCTX-M-group 9 was the predominant transposable elements of the ESBL genes. Among the thirteen fosfomycin resistant isolates, functionless transporters were identified in 9 isolates. Three isolates contained novel amino acid substitutions (Asn67Ile, Phe151Ser and Trp164Ser, Val146Ala and His159Tyr, respectively) in MurA (the target of fosfomycin). Four isolates had fosfomycin modified enzyme (fosA3) in their plasmids. The fosA3 gene was harboured in an IncN-type plasmid (101 kbp) in the three pig isolates and an IncB/O-type plasmid (113 kbp) in the human isolate. In conclusion, we identified that 6% and 23% of the ESBL-producing E. coli from human and pigs were resistant to fosfomycin, respectively, in Taiwan. No clonal spread was found between human and pig isolates. Functionless transporters were the major cause of fosfomycin resistance, and the fosA3-transferring plasmid between isolates warrants further monitoring.

Dataset Information

Molecular characterization of beta-lactamase genes and their genetic structures in Acinetobacter genospecies 3 isolates in Taiwan.

Publications

Molecular characterization of beta-lactamase genes and their genetic structures in Acinetobacter genospecies 3 isolates in Taiwan.

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