Phenotypic and Genotypic Analysis of Haemolysin Genes of Staphylococcus aureus Isolated from Subclinical Mastitis in Savojbolagh County, Alborz Province

Staphylococcus aureus pathogens are known in animals and humans. They cause various infections such as mastitis in cattle, sheep and goats, as well as dermatitis, poisoning and even in some cases severe infections such as toxic shock syndrome (TSS) in humans. The bacteria also lead to severe economic losses and mortality in dairy industry, due to the fact that the bacteria can become resistant to antibiotics as a result of treatment makes it difficult. Studies have shown that there is a relationship between mastitis and bacterial virulence factors, one of which is haemolysin enzyme. The aim of this study was to analyze the phenotypes and genotypes of haemolysin genes in Staphylococcus aureus isolated from 540 subclinical bovine mastitis in Savojbolagh county, Alborz province. Subclinical mastitis-affected quarters which has been detected by CMT, were cultured in the laboratory. Staphylococcus aureus samples positive for coagulase test were analyzed by PCR and the results of PCR and culture were compared. Of 420 subclinical bovine mastitis samples, 84(20%) were determined positive by culture. Fifty (59.53%) samples were found positive by coagulase test. Forty five samples (90%) out of this 50 were positive by PCR test. These 45 samples were culture on blood agar and analyzed by PCR . The results showed that in some cases, based on bacterial cultures, haemolysin virulence genes were well expressed and the results almost collapsed with the results of PCR. Hence, we can say that in most cases, there is a significant relationship (P value = 0/001) between the phenotypes and genotypes of virulence genes. However, there is no direct relation, because in some cases, genes are not expressed in culture as well and this is quite obvious in alpha haemolysin gene.