Analysis of Hyaluronidase Expression by qPCR in Egyptian Clinical Isolates of <i>Staphylococcus aureus</i> and Its Correlation with Phenotypic Plate Assay

Hyaluronidase enzyme (HysA) is an extracellular enzyme that is considered to be an important virulence factor for Staphylococcus aureus. We screened the production of HysA enzyme in the spent media of Egyptian clinical isolates (32 isolates) via phenotypic plate assay. We found that 75% of the isolates (24 isolates) were able to produce HysA enzyme. We designed primers for qPCR analysis of hysA mRNA expression that was derived from the alignment of hysA gene sequences of 41 strains of S. aureus. The designed primers could be used for the amplification of hysA in 79.2% of the isolates (19 isolates) that were positive for HysA production as demonstrated by phenotypic plate assay. A significant positive correlation, as indicated by Pearson correlation analysis (r = 0.84 at P u003c 0.001), was found between phenotypic plate assay and qPCR of mRNA expression of hysA in the investigated isolates of S. aureus. In conclusion, we analyzed for the first time hysA mRNA expression via qPCR in S. aureus. Additionally, our work showed a good agreement between the phenotypic assay of HysA production via plate assay and hysA expression in S. aureus. The qPCR analysis of this study could be used as a more reliable quantitative method for hysA expression analysis particularly in infected animal models of S. aureus.