Prevalence and Expression of PSM A Gene in Biofilm-Producing Staphylococcus aureus Clinical Isolates

Abstract

Background: Staphylococcus aureus is a frequent cause of hospital and community-associated infections on a global scale. This pathogen is responsible for causing an extensive range of diseases and sometimes create biofilms for their survival. Biofilm formation, leads to difficulty in treatment with antibiotics and antibiotic resistance which is another rising concern in health centers. Some S. aureus virulence factors encode on the core genome, such as alpha-toxin and phenol-soluble modulins (PSMs), which are produced by nearly all strains. Objectives: There is no information about the expression of PSM A gene in clinical isolates of biofilm-producing S. aureus in Iran. This study was performed on clinical samples to determine the prevalence and expression of PSM A gene in biofilm-producing S. aureus clinical isolates. Methods: The clinical samples were collected and examined for S. aureus by microbiological and biochemical tests. Then, the biofilm formation in S. aureus isolates was detected by microtiter plate. Finally, the expression of PSM A was determined using SYBR Green real-time PCR. Results: From a total of 60 isolates of S. aureus, 47 strains (78.3%) had ability of biofilm formation and the others were negative for biofilm formation. Real-time PCR testing showed that 100% of the strains were positive for biofilms and PSM A genes. The results of phenotypic and genotypic tests of biofilm were closely related to each other and the expression of PSM A gene was 80%. It was found that 100% of strains were biofilm producing and PSM A gene was present in 78.3% (47 strains) of them. Conclusions: The prevalence of biofilm production in S. aureus strains isolated from clinical samples was high, so it is highly important to monitor the prevalence of these organisms in hospitals and community as well as their antimicrobial resistance.