Genetic characterization of virulence and extended spectrum β-lactamase producing genes of isolated from bovine milk.

Mastitis associated species were isolated from bovine milk to characterize virulence genes ( and ) and extended spectrum β-lactamase (ESBL) genes (, , , , and ). A total number of 325 bovine milk samples (195 raw and 130 mastitic milk specimens) collected from Banaskantha, a milk-shed district of Gujarat, India, were included in the study. A total number of 27 isolates were recovered, consisting of 17 (62.96%) isolates from raw milk and 10 (37.03%) isolates from mastitic milk samples, giving an overall prevalence of 8.31%. Antibiotic sensitivity patterns revealed that 20 out of 27 isolates were found to be multi-drug resistant. Based on combination disc diffusion test and HiCrome ESBL agar method, 20 (74.07%) and 25 (92.59%) isolates were detected as ESBL producers, respectively. Among virulence genes studied, presence of (25/27; 92.59%) was higher than (5/27; 18.51%). Beta-lactamase genes , and were detected in 23/27 (85.18%), 3/27 (11.11%) and 2/27 (7.40%) of isolates, respectively; while, none of the isolates was found to be positive for and genes. Outcome of the study provided an insight into virulence genes and ESBL producing isolated from bovine milk samples in India.