Abstract

MOLECULAR STUDY OF SOME VIRULENCE GENES DETERMINATE IN STAPHYLOCOCCUS AUREUS ISOLATED FROM MILK BOVINE MASTITIS.

Zeyad SH. Abbas*, Mohammad I. Nader and Ilham A. Khalaf

ABSTRACT

Mastitis is one of the common diseases of dairy cattle and an inflammatory response of the mammary glands tissue. Staphylococcus aureus is probably the most lethal agent Staphylococcus aureus is the main etiological agent of contagious clinical/subclinical mastitis in dairy herds. The aim of this study aims at the genotypic characterization of S. aureus strains isolated from dairy cows suffering from mastitis in the different regions (Abu Ghraib, Taji, Latifiya, Yousofia, Al-futailia) in Iraqi-Baghdad farms. A total of 60 S. aureus strains, obtained from 120 dairy cows, were phenotypically characterized and identified. Amplification of genes encoding clumping factor (clfA), coagulase (coa), thermonuclease (nuc), enterotoxin A (entA), and the gene segments encoding the immunoglobulin G binding region and the X region of protein A gene (spa) by Polymerase Chain Reaction was used for the genotypic characterization of isolated S. aureus strains. There was a statistical difference between isolates obtained from samples collected from cows infected in mastitis (P <0.01). All of the isolates are posative for nuc and spa genes, 36 out of 60 isolates are posative of the polymorphic ClfA gene and X-region binding was detected in 55 isolates. Amplification of the coa gene yielded five different products in 4, 12, 23, 9 and 12 isolates. The amplification of the entA gene, was observed in 41 out of 60 isolates.

Keywords: Bovine mastitis, Staphylococcus aureus, virulence factors, polymerase chain reaction (PCR), Iraq.