Abstract

Streptococcal mastitis is considered as one of the most common infectious diseases in the dairy cattle, which threatens the dairy industry all over the world. The aim of this study was to determine the prevalence of Streptococcus species in mastitic cows with molecular investigation to detect the presence of some virulence genes of the recovered isolates by PCR. A total of 150 milk samples were collected from dairy cattle with clinical and subclinical mastitis from different areas in El- Gharbia governorate, Egypt. Streptococcus species were isolated with an incidence of 38%. S. agalactiae, S. dysgalactiae, S. uberis, S. pyogenes, S. pneumoniae and S. faecalis were isolated from the milk samples of the examined cows with the percentage of 14.7%, 6%, 9.3%, 4.7%, 1.3% and 2%, respectively. Molecular investigation of virulence associated genes revealed that sip, cfb and bca genes of S. agalactiae were found with the percentage of 77.7%, 88.8% and 33.3%, respectively. The mig gene of S. dysgalactiae was found with an incidence of 77.8%. Of the examined S. uberis isolates, 55.5%, 22.2% and 33.3% were carrying the cfu, oppF and has A genes, respectively. The present study revealed the prevalence of Streptococci and distribution of virulence associated genes among the isolates. The high frequency of virulence genes in the isolates suggests an important role of these virulence genes in the pathogenesis of Streptococci in cattle mastitis.

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