Prevalence of CTX-M-Type β-Lactamases in Multi–Drug Resistant Escherichia coli Isolates from North of Iran, Rasht

Introduction: One of the most important resistance determinants in Enterobacteriaceae are extended spectrum β-lactamases (ESBLs). During the last decade, CTX-M types ESBLs have increased considerably and become the most common ESBLs worldwide which are the major causes of the urinary tract infections (UTIs). The aim of this study was to determine the antibiotic resistance patterns and the frequency of the CTX-M β-lactamases among multi-drug resistant (MDR) Escherichia coli (E. coli) isolates from northern Iranian patients with UTI. Materials and methods: Thirty three E. coli isolates from urine samples were applied in this study. Double disk synergy test (DDST) was applied for identification of ESBL phenotypes in E. coli isolates. The ESBL related genes, CTX-M group (1, 2, 8 and 9), were amplified by polymerase chain reaction (PCR). Results: All E. coli isolates showed sensitivity to piperacillin and 55% of the isolates were resistant to 3 and 4 cephalosporins. The presence of the blaCTX-M gene in 88% of the ESBL producing isolates was approved based on molecular method. CTX-M (1, 2, 8 and 9) containing E. coli isolates showed resistance to more antibiotics than non-CTX-M isolates. CTX-M-1 was the most prevalent CTX-M determinant in ESBL producing E. coli isolates. Discussion and conclusion: Based on the results of the present study, the preferred antibiotic against CTX-M type ESBL-producing E. coli strains in north of Iran, Rasht, should be piperacillin. Although, CTX-M type ESBLs prevalence was nearly low in the studied MDR E. coli isolates, but controlling these low prevalence isolates is important.