Detection of virulence genes and determination of the antimicrobial susceptibility of Escherichia coli isolates with mastitis in Mashhad, Iran – a short communication

The purpose of this study was to determine the virulence genes and antimicrobial resistance patterns of Escherichia coli isolated from milk samples of cows with bovine mastitis. Forty-seven E. coli isolates from clinical mastitis milk samples, from five dairy farms in Northeast of Iran, were subjected to multiplex PCR to determine virulence genes stx1, stx2, eaeA, hlyA, sta, F4, F17, fliC, and rfbE. In addition, antimicrobial susceptibility was assessed by applying disk diffusion methods. The eaeA and stx1 genes were most frequently detected in 42 (89.3%) and 34 (72.3%) isolates, respectively. However, the least frequent gene was F41 as it was found in only one isolate (2.1%). Furthermore, 9 out of 47 isolates were hlyA positive, and four isolates harbored the sta gene. The antimicrobial susceptibility demonstrated the highest resistance against lincomycin (100%) and neomycin (91.4%). Since these bacteria represent a high-risk pathogen on farms, the emergence of multiple antibiotic-resistant and pathogenic E. coli strains should be of great concern for public health.