Detection Of The Coa Gene In Staphylococcus aureus From Different Sources By Polymerase Chain Reaction

Abstract

One hundred and ninety eight samples of human and animal sources from different areas in El-Sharkia Governorate were used in this study to isolate Staphylococcus species and to determine the presence of coagulase ( coa) gene,a virulence gene detected in S. aureus (CoPS), by PCR. Primary isolation on mannitol salt agar, β-haemolysis, tube coagulase test (TCT) and other biochemical characterization revealed that 32.8% (65/198) of the total samples were infected with staphylococci, only 35 isolates were biotyped as coagulase-positive staphylococci (CoPS) and represented as 8 (8.8%), 10 (22.2%) and 17 (26.9%) in milk, meat and human samples, respectively. Meanwhile, Coagulase-negative Staphylococc i (CoNS) were obtained only from cows milk. Fifteen CoPS (5 milk samples, 4 meat products and 6 huma n samples) were subjected to analysis by PCR for detection of coa gene. The resulted amplicons were 648, 723, 812 and 913 bp. According to coa gene polymorphism, milk and meat isolates were grouped into 5 groups, while human isolates were grouped into 4 groups. It was noted that two of the strains, classified as coagulase negative by tube coagulase test were found to be positive with PCR amplification of the gene which clearly emphasizes the use of molecular methods in detecting S. aureus. In conclusion, the coa amplification has been considered as a simple and accurate method for typing of S. aureus.