Abstract

In the present study, 15 S. agalactiae out of 56 streptococcal isolates recovered from 98 milk samples collected from clinical cases, one organized farm and two unorganized sectors in and around Bangalore. All the streptococcal isolates were confirmed at genus level using genus specific primers targeting tuf gene of Streptococcus. Species level identification for S. agalactiae, S. dysgalactiae and S. uberis was done using 16S rRNA. Primers were designed for targeting cfb gene of S. agalactiae, mig gene of S. dysgalactiae, whereas for targeting sip, hyl gene of S. agalactiae and skc, pauA gene of S. uberis either published or designed earlier were used to screen for virulence genes of streptococcal isolates and reference strains. Desired amplicons for the virulence genes were obtained. All the S. agalactiae isolates were also screened for CAMP factor phenotypically by employing CAMP test which was demonstrable in fourteen isolates but cfb gene encoding for CAMP factor was detectable by PCR in all the isolates. The study ultimately helps us to understand the virulence characteristics and mechanisms behind emergence of new strains or shifts in mastitis epidemiology in response to control measures, including antibiotic treatment and vaccination.

Key words: Streptococci, virulence factors, bovine mastitis, CAMP factor.