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Detection of OXA‐type carbapenemases and integrons among carbapenem‐resistant Acinetobactor baumannii in a Teaching Hospital in China
Author(s) -
Hu Qiaojuan,
Hu Zhidong,
Li Jing,
Tian Bin,
Xu Hairu,
Li Jin
Publication year - 2011
Publication title -
journal of basic microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0233-111X
DOI - 10.1002/jobm.201000402
Subject(s) - colistin , imipenem , biology , microbiology and biotechnology , acinetobacter baumannii , carbapenem , genotyping , gene , drug resistance , antimicrobial , antibiotics , antibiotic resistance , genotype , genetics , bacteria , pseudomonas aeruginosa
Abstract The increasing trend of carbapenem‐resistance (CR) and multi‐drug resistance (MDR) in A. baumannii worldwide has limited the therapeutic effectiveness of antibiotic therapy. The study was conducted to determine the prevalence of carbapenemases and integrons among the isolates of imipenem‐resistant A. baumannii (IRAB). A total of 71 non‐repetitive imipenem‐ resistant A. baumannii isolates were collected and tested for susceptibility to 17 antimicrobials. The modified Hodge test and EDTA‐disc synergy test were performed for the screening of carbapenemases and metallo‐ β ‐lactamases (MBLs) production, respectively. Isolates were then subjected to multiplex‐PCR targeting genes encoding for OXA‐type carbapenemase, MBLs and integrases. Random amplified polymorphic DNA (RAPD) genotyping was performed to assess genetic relatedness. All isolates exhibited multi‐drug resistant phenotype. Colistin was the most active antimicrobial agent tested. Seventy‐one isolates (100%) demonstrated positive in the modified Hodge test. Thirty‐nine isolates showed positive in the EDTA‐disc synergy test, however, no MBL genes were detected. All strains possessed a bla OXA‐51 ‐like gene. The co‐exis‐tence of bla OXA‐51 ‐like/ bla OXA‐23 ‐like/ intI1 , bla OXA‐51 ‐like/ bla OXA‐23 ‐like, bla OXA‐51 ‐like/ bla OXA‐24 ‐like was detected in 91.6% ( n = 65), 5.6% ( n = 4), 2.8% ( n = 2), respectively. Analysis of the genetic con‐text of bla OXA‐23 showed the presence of IS Aba1 upstream of bla OXA‐23 . No IS Aba1 was detected upstream of bla OXA‐51 . Two different gene cassettes were found in these strains, and a high prevalence of aacA4, aadA1 and catB8 genes was observed. RAPD of 71 isolates showed 7 genotypes. The strains were mainly recovered from patients in intensive care unit, neurosurgery and department of respiratory disease. These ndings show that multi‐drug resistance in A. baumannii is a common problem. This study also shows a high distribution of bla OXA‐23 ‐like and intI1 genes in imipenem‐resistant A. baumannii isolates. The clonal spread played an important role in the increase of OXA‐23 producing IRABs in the hospital environment. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)