Concurrent of blaCTX-M and blaNDM-1 genes in clinical isolates of Escherichia coli from northern Iran.

The emergence of E. coli producing extended-spectrum β-lactamases and metallo β-lactamases has been reported as an important cause of treatment failure. The present study aimed to evaluate the existence of blaCTX-M, blaTEM, blaSHV, blaNDM-1 and blaIMP1 genes among E. coli isolated from patients in Babol, Northern Iran. The pattern of antibiotic resistance and the prevalence of multidrug-resistant (MDR) E. coli isolates were determined. E. coli isolates were separated from clinical specimens and antimicrobial susceptibility test (AST) was performed using the disk diffusion method. These isolates were further evaluated for the production of ESBLs and MBLs enzymes using cefotaxime (CTX), ceftazidime (CAZ) disks with and without clavulanic acid, and two CAZ with 2 mercaptopropionic acid disks, respectively. The ESBLs and MBLs positive isolates were analysed for the existence of blaCTX-M, blaTEM, blaSHV, blaNDM-1 and blaIMP-1 genes with the conventional PCR method. Of 259 isolates, 117 β-lactamase producing E.coli were detected. MDR isolates were observed in 110/117 (94.9%) E. coli. Among 117 isolates, ESBLs, MBLs and coproduction of ESBL and MBL enzymes were observed in 45, 7 and 65 isolates, respectively. PCR analysis showed that the predominant genes were blaCTX-M15(95.5%) and blaNDM-1 (31.9%) among ESBL and MBL producing E. coli, respectively. Also, the concurrent occurance of the blaCTX-M with blaTEM, blaSHV, blaNDM-1 and blaIMP-1 genes were demonstrated. In conclusion, high prevalence rate of MDR isolates, particularly ESBL and MBL producing E. coli, observed in the current study shows the necessity of control and management strategies for the aforementioned isolates. Also, the early detection of concurrent ESBLs and MBLs producing E. coli is necessary to avoid treatment failure and prevent the distribution of such bacteria.