Phenotypic Assessment of Exoenzyme Activity by Clinical Isolates of Staphylococcus aureus


  • Yusra Siddiqui Jinnah University for Women, Karachi


Enzyme, Phenotypic test, Staphylococcus aureus, Virulence


Staphylococcus aureus is a common causative agent of hospital infection and community acquired infection as the cell possesses a wide armamentarium of virulence factor that include different exoenzyme and toxins. The main aim of this study was to evaluate the virulence factor from clinical isolates of Staphylococcus aureus. In this study total ten isolates were used for the screening of catalase, coagulase, lipase, thermonuclease, beta-lactamase and Dnase. The present study showed that 100% strains demonstrate catalase enzyme, coagulase enzyme, betalactamase. Out of 10 strains only 2 (20%) strains produced Dnase and thermonuclease enzyme while only 30% strains showed positive result for lipase production which was detected by phenol red test. Based on the result of this study almost all the strains showed positive result for various enzymatic tests but 3 strains considered to be more virulent as they showed the production of Dnase, lipase and thermonuclease. The enzymes make Staphylococcus aureus more pathogenic and give rise to diverse spectrum of diseases ranging from minor to life threatening infections. Phenotypic tests offers an alternative method for simultaneous detection of the clinically important virulence factors of Staphylococcus aureus strains for diagnostic purposes as well as research studies.

Author Biography

Yusra Siddiqui, Jinnah University for Women, Karachi

Department of Microbiology