Virulence Determinants of Buffalo Mastitis Originated Streptococcus agalactiae Isolates

Abstract

Streptococci as a cause of mastitis have become the major concern to the dairy industry worldwide due to huge economic losses. Streptococcus agalactiae is a major contagious mastitis pathogen and continues to be a major cause of mastitis in dairy cattle and buffaloes. The aim of the study was to investigate the virulence determinants of S. agalactiae strains isolated from buffalo milk. Within the scope of the study, 24 S. agalactiae isolates from buffalo mastitis were examined. Biofilm production of isolates was investigated phenotypically by CRA method. It was observed that 18 (75%) isolates were positive for biofilm production. The presence of hylB, fnbB, scpB and spb1 virulence genes in S. agalactiae isolates were investigated by PCR. It was determined that 19 (79.17%) of the isolates were positive for scpB and 6 (25%) for fnbB virulence genes. None of the isolates were found to contain hylB and spb1 virulence genes. The antibiotic resistance profiles of the isolates among kanamycin, ampicillin, enrofloxacin, erythromycin, tetracycline, trimethoprim-sulfamethoxazole antibiotic discs were determined by Kirby Bauer Disc Diffusion Method. Resistance were evaluated as % 41.7, % 45.9, % 25, % 12.5, % 20.9, and % 33.3, respectively. RAPD-PCR patterns of all isolates were determined using the ERIC-2 primer. The dendrograms of the RAPD patterns were plotted with the UPGMA method. It was determined that the isolates showed similarity between 59-95%. In conclusion, the research confirms the prevalence of various virulence genes in S. agalactiae isolated from buffalo mastitis. Further studies are therefore necessary to determine the molecular epidemiology and variability of S. agalactiae isolated from buffaloes, with the aim of improving mastitis control programs with regard to S. agalactiae.