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Clinical carbapenem-resistant Acinetobacter baylyi strain coharboring blaSIM-1 and blaOXA-23 from China.

ABSTRACT: bla(SIM-1) and bla(OXA-23) were codetected in clinical carbapenem-resistant Acinetobacter baylyi strain NB09A30. Both of carbapenemase genes were located on a large plasmid (ca. 360 kb). bla(SIM-1) was found as a gene cassette inserted into a class 1 integron identical to that determined in Acinetobacter sp. isolates from South Korea. The genetic structure of bla(OXA-23) in NB09A30 was different from that in the prevalent Acinetobacter baumannii of clonal complex 92 (CC92) from the same hospital.

SUBMITTER: Zhou Z

PROVIDER: S-EPMC3195060 | biostudies-literature | 2011 Nov

REPOSITORIES: biostudies-literature

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Clinical carbapenem-resistant Acinetobacter baylyi strain coharboring blaSIM-1 and blaOXA-23 from China.

Zhou Zhihui Z Du Xiaoxing X Wang Li L Yang Qing Q Fu Yiqi Y Yu Yunsong Y

Antimicrobial agents and chemotherapy 20110829 11

bla(SIM-1) and bla(OXA-23) were codetected in clinical carbapenem-resistant Acinetobacter baylyi strain NB09A30. Both of carbapenemase genes were located on a large plasmid (ca. 360 kb). bla(SIM-1) was found as a gene cassette inserted into a class 1 integron identical to that determined in Acinetobacter sp. isolates from South Korea. The genetic structure of bla(OXA-23) in NB09A30 was different from that in the prevalent Acinetobacter baumannii of clonal complex 92 (CC92) from the same hospital ...[more]

PMID: 21876057

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Project description:Carbapenem-resistant Acinetobacter baumannii (CRAB), which belonged to global clones 1 (GC1) or 2 (GC2), has been widely reported and become a global threat. However, non-GC1 and non-GC2 CRAB strains are not well-studied, especially for those with rare phenotype. Here, one pyomelanin-producing CRAB strain (A. baumannii DETAB-R21) was isolated from oral swab in the ICU. Antimicrobial susceptibility testing showed it was resistant to carbapenems, ceftazidime, levofloxacin, and ciprofloxacin. DETAB-R21 was ST164Pas and ST1418Oxf with KL47 and OCL5, respectively. Whole-genome sequencing (WGS) analysis revealed chromosome contained three copies of blaOXA-23 on three 4,805-bp Tn2006 composite transposons with various novel 9-bp target site duplications (TSD). A Tn125-like structure, including blaNDM-1, a novel 4,343 bp composite transposon encoding blaCARB-16, and three prophage regions were also identified. Importantly, hmgA was interrupted by a Tn2006 and contributed to pyomelanin production and further confirmed by hmgA overexpression. Furthermore, A. baumannii irradiated with UV light, DETAB-R21 showed a higher relatively survival rate compared to a control strain that did not produce pyomelanin. No effects of pyomelanin were observed on disinfectants susceptibility, growth, or virulence. In conclusion, pyomelanin-producing CRAB carrying the blaNDM-1 and blaOXA-23 genes embedded in the bacterial chromosome is of grave concern for health care settings, highlighting the need for effective measures to prevent further dissemination. IMPORTANCE Pyomelanin production is a quite rare phenotype in A. baumannii. Moreover, the mechanisms leading to the pyomelanin production was still unclear. Here, we for the first time, confirmed the mechanism of pyomelanin production, and further investigated the impact of pyomelanin on disinfectants susceptibility, growth, virulence, and UV irradiation. More importantly, many mobile genetic elements (MGEs), including three copies of Tn2006 composite transposons, one copy of blaNDM-1 on the Tn125-like structure and three prophage regions, were identified in the chromosome, demonstrated strong plasticity of A. baumannii genome. Our study provides important insights into the new rare ST164Pas A. baumannii strain with high level carbapenem resistance, which is of great threat for patients. These findings will provide important insights into the resistance gene transfer via transposition events and further spread in the clinic.

Project description:The prevalence of carbapenem-resistant Acinetobacter baumannii in hospitals has been increasing worldwide. This study aims to investigate the carbapenemase genes and the clonal relatedness among A. baumannii clinical isolates in a Chinese hospital.Carbapenemase genes and the upstream locations of insertion sequences were detected by polymerase chain reaction (PCR), and the clonal relatedness of isolates was determined by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing.A total of 231 nonduplicate carbapenemase gene-harboring A. baumannii clinical isolates recovered from Shenzhen People's Hospital, were investigated between 2002 and 2009. blaOXA-23-like, blaOXA-58-like, blaOXA-40-like, and ISAba1-blaOXA-51-like were identified in 119, 107, 1, and 4 isolates, respectively. IS1008-?ISAba3, ISAba3, and ISAba1 were detected upstream of the blaOXA-58-like gene in 69, 35, and 3 isolates, respectively. All blaOXA-23-like genes but one had an upstream insertion of ISAba1. blaOXA-58-like was the most common carbapenemase gene in A.baumannii before 2008, thereafter blaOXA-23-like became rapidly prevalent and replaced blaOXA-58-like in 2009. The majority of blaOXA-58-like-carrying isolates showed lower level of resistance to imipenem and meropenem (minimum inhibitory concentrations (MICs), 1 ?g/ml to 16 ?g/ml), compared with the majority of blaOXA-23-like-carrying isolates (MICs, 16 ?g/ml to 64 ?g/ml for both imipenem and meropenem). All 231 blaOXA carbapenemase gene-harboring isolates belonged to 14 PFGE types (A-N), and three dominant clones A, J, and H accounted for 43.3%, 42.0%, and 8.2% of the tested isolates, respectively. Clone A (sequence type ST92/ST208) with blaOXA-58-like was the most prevalent before 2008. Clone H (ST229) with blaOXA-23-like became striking between 2007 and 2008. Clone J (ST381) with blaOXA-23-like rapidly spread and replaced clones A and H in 2009.This study is the first to reveal that the distinct blaOXA-23-like-carrying A. baumannii ST381 displaced the previously prevalent blaOXA-58-like-carrying A. baumannii ST92/ST208, resulting in the rapidly increasing resistance to carbapenems in A. baumannii in Shenzhen People's Hospital in 2009.

Project description:The rate of recovery of carbapenem-resistant Acinetobacter baumannii (CRAB) isolates has increased significantly in recent decades in Taiwan. This study investigated the molecular epidemiology of CRAB with a focus on the mechanisms of resistance and spread in isolates with blaOXA-23-like or blaOXA-24-like All 555 CRAB isolates in our multicenter collection, which were recovered from 2002 to 2010, were tested for the presence of class A, B, and D carbapenemase genes. All isolates with blaOXA-23-like or blaOXA-24-like were subjected to pulsed-field gel electrophoresis, and 82 isolates (60 isolates with blaOXA-23-like and 22 isolates with blaOXA-24-like) were selected for multilocus sequence typing to determine the sequence type (ST) and clonal group (CG) and for detection of additional β-lactamase and aminoglycoside resistance genes. The flanking regions of carbapenem and aminoglycoside resistance genes were identified by PCR mapping and sequencing. The localization of blaOXA was determined by S1 nuclease and I-CeuI assays. The numbers of CRAB isolates carrying blaOXA-23-like or blaOXA-24-like, especially those carrying blaOXA-23-like, increased significantly from 2008 onward. The blaOXA-23-like gene was carried by antibiotic resistance genomic island 1 (AbGRI1)-type structures located on plasmids and/or the chromosome in isolates of different STs (CG92 and novel CG786), whereas blaOXA-24-like was carried on plasmids in CRAB isolates of limited STs (CG92). No class A or B carbapenemase genes were identified. Multiple aminoglycoside resistance genes coexisted in CRAB. Tn6180-borne armA was found in 74 (90.2%) CRAB isolates, and 58 (70.7%) isolates had Tn6179 upstream, constituting AbGRI3. blaTEM was present in 38 (46.3%) of the CRAB isolates tested, with 35 (92.1%) isolates containing blaTEM in AbGRI2-type structures, and 61% of ampC genes had ISAba1 upstream. We conclude that the dissemination and spread of a few dominant lineages of CRAB containing various resistance island structures occurred in Taiwan.

Dataset Information

Clinical carbapenem-resistant Acinetobacter baylyi strain coharboring blaSIM-1 and blaOXA-23 from China.

Publications

Clinical carbapenem-resistant Acinetobacter baylyi strain coharboring blaSIM-1 and blaOXA-23 from China.

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