تشخيص مولكولي ژنهاي بتالاكتامازي CTX&PER در سويه هاي E.coli جداشده از نمونه هاي كلينيكي از بيمارستان هاي تهران

CTX-M and PER Beta-Lactamases in Clinical Isolates of E. coli Isolated from Tehran hospitals

Background and objective: E. coli species are able to produce Extended-Spectrum (3-lactamases (ESBLs) such as CTX and PER, that cause high resistance to the Beta-Lactam antibiotics. Thus the identification of antibiotic resistant pattern to (3-Lactam antibiotics has a great impact on treatment and control measures of these infections. The survey of antibiotic susceptibility patterns, identification of ESBLs and detection of blacTx and blaPER in clinical isolates of E. coli were the objects of this study. Materials and methods: 260 isolates of E. coli collected from Tehranʹs hospitals. The antibiotic susceptibility patterns against various antibiotics and MIC for Ceftazidime determined by disk diffusion and microbroth dilution method, respectively (CLSI). The ESBL producers were screened by Phenotypic Confirmatory Test (PCT). PCR was performed for detection of blacTx and blapER genes. Results: All strains were susceptible to imipenem. The minimum and maximum resistance rates against investigated antibiotics were to Amikacin 12.7% and Carbenicillin 86.9% respectively. 49.2% of the isolates were ESBL positive in PCT. the CTX-M was detected in 38% of isolates. No isolates were positive for PER beta-lactamase gene. Conclusion: It is necessary to control the transmission and outbreak of ESBL producing organisms which is responsible for increasing in nosocomial infections. Our results showed that the ESBL producing organisms have high prevalence in Tehranʹs hospitals. Accurate laboratory detection is important to avoid the clinical failure due to inappropriate antimicrobial therapy .Also it has been found ESBL positive isolates without remarkably increasing in Ceftazidime MIC.