Detection and characterization of Enterobacteriaceae family members carried by commensal Rattus norvegicus from Tehran, Iran

Wild rats are known to carry different microorganisms and are considered a reservoir of zoonotic pathogens worldwide. The urban rats were collected from five districts of Tehran and Gram-negative bacteria (GNB) were isolated from fecal samples and were identified using classical biochemical tests. The antibiotic susceptibility patterns of isolated bacteria were determined by Kirby–Bauer disk diffusion method, the results of which were interpreted in line with CLSI guideline. The frequency of antibiotic-resistant genes was identified using multiplex-PCR. Moreover, PCR method was used to identify the frequency of Escherichia coli O157:H7 and main categories of diarrheagenic E. coli including EPEC, ETEC, EIEC, EAEC, and STEC pathotypes. A total of 100 Rattus norvegicus were trapped and fecal samples were collected. Overall, 72 fecal samples were positive for GNB. E. coli ( n = 46/72) had the highest frequency among the isolated GNB. Among E. coli isolates, the highest and lowest resistance rates belonged to ampicillin (56.5%) and ceftriaxone (0%), respectively. Klebsiella spp. was 100% resistant to imipenem, and streptomycin (0%) was the most effective antimicrobial agent on Klebsiella spp. Among surveyed genes, bla TEM (95.8%) and bla aadA-1 (58.3%) had the highest frequency, while bla KPC , and bla CMY-2 were not detected among Enterobacteriaceae . Herein, O157: H7 serotype was not detected and aEPEC (87%) was the most common pathotype detected. Results suggested that rodents might be a reservoir of antimicrobial-resistant pathogens and rodent control along with implementation of surveillance programs should be considered as a critical priority for urban health.