Isolation, Antibiogram and Molecular Characterization of Group B Streptococci Isolates from Bovine Mastitis

Background: Group B streptococcus (GBS) or Streptococcus agalactiae is an important pathogen associated with bovine mastitis. The organism is also of public health consequences and may cause variety of infections ranging from neonatal sepsis, pneumonia and meningitis to localized infections and urinary tract infection or arthritisin adult humans. Widespread use of antibiotics in veterinary medicine has led to development of resistance among the pathogens. So there is need for surveillance of antimicrobial resistance to ensure effective treatment. Methods: Milk samples collected from mastitis affected animals were processed for isolation of Streptococcus agalactiae. The isolates were tested for antimicrobial susceptibility. Molecular characterisation was carried out by PCR to study the occurrence of resistance marker genes and virulence marker genes. RAPD was carried out to study genetic diversity among the isolates. Result: Six isolates of S. agalactiae were obtained from 182 milk samples. Highest resistance was observed against co-trimoxazole and tetracycline followed by ampicillin. tetM gene and tetO genes could be amplified in four and three isolates, respectively. None of the isolates showed amplification for ermA, ermB, mefA and mefE genes. Three isolates were positive for the five virulence genes tested (glnA, cfb, hylB, scaA and cyl). RAPD analysis demonstrated great intraspecific genetic diversity among the streptococcal isolates.