frequency of extended spectrum beta lactamase and CTX M-I of Escherichia coli isolated from the urine tract infection of patients by phenotypic and PCR methods in the city of Khoy in Iran

ABSTRACT

The production of Extended Spectrum Beta Lactamases [ESBLs] by Escherichia coli is the main cause of resistance to Cephalosporins. In the past decade, CTX-M enzymes have become the most prevalent ESBLs in Europe, Canada, and Asia. In this study, the frequency of ESBL- producing E.coli and molecular detection of the CTX-M-I group was investigated. A total of 400 urine samples were collected from both hospitalized and out-patients in Khoy's hospitals between November 2009 and April 2010. Out of these samples, 188 were identified as E.coli by standard biochemical tests. The antibiotic Susceptibility tests to 10 antibiotics were performed by the-disk-agar diffusion [DAD] method. ESBL production was screened by phenotypic test that including disk diffusion agar and combined disk as recommended by the Clinical and Laboratory Standards Institute [CLSI] Screened isolates were investigated by PCR assay for detection of CTX-M-I group genes. The results show that out of 188 E.coli isolates identified, 56 [29.8%] were producing ESBls by phenotypic test. All isolates were sensitive to imipenem. Overall, 49 [87.5%] isolates were confirmed as CTX-M-I producer by PCR. The results of this study showed that about 30% of the identified E.coli were producing ESBL Therefore, we recommend to use molecular methods in such researches