Prevalence, Molecular Characterization and Serology of Shiga toxin-Producing Escherichia coli Isolated from Buffaloes in West Azerbaijan, Iran

This present study is the first to report the presence of Shiga toxin-producing Escherichia coli (STEC) in buffaloes in Iran. A total of 360 fecal samples were collected from buffaloes from different regions in the west Azerbaijan province of Iran and cultured for the isolation of E. coli using routine biochemical tests. From the fecal samples, 340 E. coli were isolated and, of these, 26 STEC isolates were identified. The STEC isolates were further analyzed for the presence of specific virulence genes. Among the STEC isolates, 11 (42.3%) isolates were positive for the stx1 gene, nine (34.6%) were positive for the stx2 gene and six (23%) were positive for both of these genes. Six (23%) STEC isolates harbored the hly gene and two (7.6%) isolates were positive for the eae gene. Based on serotyping, only one (3.8%) isolate was of the O157 serotype, while the other 25 (96.1%) belonged to non-O157 serotypes. The results of the present study provide the first evidence that buffaloes could be a reservoir for STEC in Iran, especially those belonging to non-0157 serotypes.