Isolation, identification and virulence determinants of Streptococcus agalactiae from bovine subclinical mastitis in Egypt

  • Khaled Abd EL-Hamid Abd El-Razik Department of Animal Reproduction, National Research Center, Giza, Egypt
  • Amany A Arafa Department of Microbiology and Immunology, National Research Center, Giza, Egypt
  • Ehab A Fouad Department of Microbiology and Immunology, National Research Center, Giza, Egypt
  • Abdelgayed M Younes Department of Hydrobiology, National Research Center, Giza, Egypt
  • Abdulaziz M Almuzaini Department of Veterinary Medicine, College of Agriculture and Veterinary Medicine, Qassim University, Buraydah, Saudi Arabia
  • Amr M Abdou Department of Microbiology and Immunology, National Research Center, Giza, Egypt
Keywords: S.agalctiae, Subclinical mastitis, Virulence genes, PCR

Abstract

Introduction: This study aimed to investigate the prevalence of contagious mastitis caused by Streptococcus agalctiae (S. agalactiae) in cattle from households and small-scale dairy farms in Egypt. Molecular characterization of S.agalactiae isolates was described including the genetic determinants of virulence to assess the genetic variation in isolated strains of S. agalactiae.

Methodology: Three hundred and sixty milk samples were collected from 90 apparently healthy dairy cows randomly selected from household and small-scale dairy farms were examined by Somatic Cell Count (SCC) as an indicator for subclinical mastitis. S.agalactiae isolates were bacteriologically and molecularly identified followed by identification of virulence genes using PCR.

Results: A total of 172 milk samples (47.77%) were positive with SCC > 200×103/ml. Bacteriological examination of the positive SCC milk samples revealed that 28 (16.28%) of the isolates were S.agalactiae. Molecular examination using PCR confirmed only 22 isolates of S. agalactiae (12.8%). Moreover, we used the pattern of virulence genes to address the genetic variation of S. agalactiae strains isolated from cases of contagious mastitis in cattle in Egypt. Virulence genes hylB, cylE, iagA, and bac were determined in 100%, 68.2%, 13.6% and 100% of isolates respectively.

Conclusions: The use of molecular methods for the identification of the causative agent in mastitis confirmed that, in Egypt, Streptococcus agalactiae is considered as one of the predominant infectious agents among contagious mastitis causing pathogens. The pattern of virulence genes presented the genetic diversity of highly virulent S. agalactiae strains isolated from cases of contagious mastitis in cattle in Egypt.

Published
2021-08-31
How to Cite
1.
Abd El-Razik KAE-H, Arafa AA, Fouad EA, Younes AM, Almuzaini AM, Abdou AM (2021) Isolation, identification and virulence determinants of Streptococcus agalactiae from bovine subclinical mastitis in Egypt. J Infect Dev Ctries 15:1133-1138. doi: 10.3855/jidc.12668
Section
Original Articles