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Molecular Identification of Resistance Determinants, Integrons and Genetic Relatedness of Extensively Drug Resistant Acinetobacter baumannii Isolated From Hospitals in Tehran, Iran.

Abstract：

BACKGROUND:Acinetobacter baumannii has emerged as an important nosocomial pathogen. Hospital outbreaks of extensively drug resistant (XDR) A. baumannii are a great concern. OBJECTIVES:Aims of this study were to characterize the resistance determinants and genetic relatedness of (XDR) A. baumannii isolates in hospitals in Tehran, Iran. MATERIALS AND METHODS:During a three-year study, clinical isolates of A. baumannii were collected from two hospitals in Tehran, Iran. Susceptibility testing to antibiotics was performed by disk diffusion method and XDR A. baumannii isolates were identified. Genes' encoding for carbapenemase production and integrons were identified by PCR. MICs of imipenem and meropenem were determined by agar dilution. Multiple locus variable-number tandem repeat analysis (MLVA) typing was used to determine genetic relationships of XDR isolates. RESULTS:Using PCR for amplification of bla OXA-51 , 93.9% (123.131) of isolates were identified as A. baumannii and 24.4% (30.123) were XDR. These isolates were resistant to gentamicin, ciprofloxacin, amikacin, cotrimoxazole, cefepime, cefotaxime, aztreonam and ceftazidime. Thirty percent of the isolates were resistant to tigecycline. All isolates were susceptible to colistin and polymyxin-B, while 93.3% (28.30) possessed bla OXA-23 -like and 6.7% (2.30) possessed bla OXA-24 -like. All isolates possessed insertion sequence (ISAba1) in the upstream region of the OXA-23-like gene. Almost 96.7% (29.30) of the isolates were positive for class I integron and 43.3% (13.30) for class II. These isolates were also positive for class I. Class III integron was not detected. MLVA typing of XDR isolates showed seven clonally complexes and 16 singletons. CONCLUSIONS:The population structure of the A. baumannii isolates in our hospitals was genetically diverse. A significant association between XDR pattern and presence of class 1 integron (P < 0.001) was found indicating that many antibiotic resistance determinants are involved in development of XDR strains.

journal_name

Jundishapur J Microbiol

journal_title

Jundishapur journal of microbiology

authors

Najar Peerayeh S,Karmostaji A

doi

10.5812/jjm.27021v2

subject

Has Abstract

pub_date

2015-07-25 00:00:00

pages

e27021

issue

eissn

2008-3645

issn

2008-4161

journal_volume

pub_type

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Molecular Identification of Resistance Determinants, Integrons and Genetic Relatedness of Extensively Drug Resistant Acinetobacter baumannii Isolated From Hospitals in Tehran, Iran.