Molecular studies regarding to virulence factors of Streptococcus species isolated from raw milk.

Ashraf, A. AbdEL-Tawab, Nahla, A. Abou El-Roos, Fatma, I. El-Hofy and Hassnaa, E. Abdullah.


The present study was performed on a total of 124 milk samples from small scale producers, farmers and markets at El-Menofyia Governorate. The prevalence of Streptococcus species in the examined samples was (65.3%), where S. agalctiae, S. dysgalactiae, S. uberis, S. pyogenes and S. pneumoniae were 28.2%, 11.3%,16.1%, 8.9% and 0.8%; respectively. The antibiogram for Streptococcus spp. revealed that vancomycin and erythromycin were the most proper antibiotics with the highest efficiency against isolated Streptococcus spp., but they were resistant to cefatriaxone and chlormphenicol. Additionally, S. agalactiae and S. dysgalactiae were sensitive to penicillin, ofloxacin ;respctively. However, S. uberis was sensitive to amoxicillin and clindamycin. By using PCR, virulence gene hyalurinidase (hyl) was detected in 25% of S. agalactiae, while a surface expressed M-like protein (mig) gene was detected in 100% of S. dysgalactiae. Also plasminogen activator (pauA) gene was detected in 100% of S. uberis isolates.

Key words

Streptococcus, raw milk, virulence gene, PCR.

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