The Prevalence and Molecular Characterization of Some Virulence Genes in S. agalactiae and S. dysgalactiae Isolates from Milk, Milk Products, and Humans in Sharkia Governorate, Egypt.

In this study, Streptococcus species were identified in 68.75% of milk samples, 69.33% of kariesh cheese, 80% of hand swabs, 77.5% of pharyngeal swabs, and 45% of vaginal swabs.From milk samples, 37 Streptococcus species isolates were identified: S. agalactiae (37.83%), S. dysgalactiae (21.62%), S. uberis (13.51%), S. pyogenes (8.11%), and S. pneumoniae (2.7%).Analysis of hand swabs revealed S. agalactiae (40%), S. dysgalactiae (10%), S. pneumoniae (10%), and both S. pyogenes and S. uberis (15% each).For pharyngeal swabs, 19 isolates included S. agalactiae (15.79%), S. dysgalactiae (5.26%), S. pneumoniae (26.32%), and S. pyogenes (36.84%).Thirty-four Streptococcus species isolates were molecularly confirmed as: S. agalactiae (n = 20), S. dysgalactiae (n =11) and S. pyogenes (n = 3).Results indicated that virulence genes scpB, rib, and lmb were present in all S. agalactiae isolates (100%) from milk and cheese.However, scpB and rib were detected in 66.7% of S. agalactiae human isolates, and lmb was found in all isolates (100%).The scpB gene was identified in all S. dysgalactiae human isolates (100%) but was not detected in S. dysgalactiae isolates from milk and cheese.The rib gene was not found in S. dysgalactiae milk isolates but was detected in all S. dysgalactiae from cheese and human (100%).The lmb gene was found in all milk and cheese S. dysgalactiae isolates, but only detected in 50% of human isolates.In conclusion, S. agalactiae and S. dysgalactiae were frequently detected in dairy products and human swabs in Sharkia Governorate, Egypt, indicating potential zoonotic transmission.The virulence genes scpB, rib, and lmb were more common in S. agalactiae from milk and cheese than in those from humans, while these genes were more prevalent in S. dysgalactiae from humans than from dairy sources.