Phylogenetic groups, extended-spectrum B-lactamases and metallo-?-lactamase in Escherichia coli isolated from fecal samples of patients with diarrhea in Iran
Gastroenterology and Hepatology from Bed to Bench,
30 July 2015
Aim: The aims of this study were to determine the phylogenetic groups and investigate phenotypic and genotypic of ESBL and MBL-producing E. coli isolates from patients with diarrhea in Kerman, southeast of Iran.
Background: Escherichia coli is detected as a significant cause of sporadic and outbreaks of diarrhea. The emergence of extended-spectrum ?-lactamases (ESBLs) and Metallo-?-lactamases (MBLs)-producing Escherichia coli caused problems in antibiotic treatments. E. coli strains can be assigned to four main phylogenetic groups, A, B1, B2 and D.
Patients and methods: Two hundred sixteen E. coli isolates were obtained from diarrheal patients between June to December 2013. Screening and confirmation tests of ESBLs and MBLs were done by disk-diffusion and broth micro-dilution methods according to CLSI 2013. The ESBL-positive isolates were screened to determine the phylogenetic groups and presence of blaCTX-M-15, blaOXA-1, blaPER-1, blaVIMand blaIMP genes by PCR.
Results: In this study, From the 216 E. coli isolates 56 ESBL-positive isolates were detected. Among ESBL-positive isolates, 51 isolates were positive for blaCTX-M-15 and one isolate were positive for both blaCTX-M-15 and blaOXA-1 genes. None of isolates were positive for blaPER-1, blaVIMand blaIMP genes. PCR assays for phylotyping of diarrhea isolates indicated that the isolates were belonged to group A (54.16%), B1 (11.11%), B2 (12.96%) and D (21.75%). ESBL-positive isolates mostly distributed in phylo-groups A and D. The isolates possessed blaCTX-M-15 gene were belonged to A (35 isolates), B1 (5), B2 (3) and D (8) phylo-groups. According to the antimicrobial susceptibility results, imipenem was found to be the most active agent, while resistance to cefotaxime was high.
Conclusion: Our results indicate that blaCTX-M-15 gene is widespread among diarrhea. ESBL-producing E. coli isolates were dissemination among diversity of phylo-groups. The adequate infection control measures are essential to prevent further dissemination of ?-lactamases and MBLs in our country.
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