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

@entity801 @entity2892 @entity3273 @entity799 @entity6944 @entity6414 @entity2177 @entity2889 @entity4509 @entity15799 @entity3524 @entity9001 @entity3064 @entity5505 @entity5646
BACKGROUND: @entity3064 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 @entity2892 and @entity2889 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 @entity801 , @entity2177 , @entity4509 , @entity799 , @entity6944 , @entity3524 , @entity5646 and @entity5505 . Thirty percent of the isolates were resistant to @entity9001 . All isolates were susceptible to @entity3273 and @entity6414 , while 93.3% (28.30) possessed bla @entity15799 -like and 6.7% (2.30) possessed bla OXA-24 -like. All isolates possessed insertion sequence (ISAba1) in the upstream region of the @entity15799 -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.
