Molecular Study of Mec-Phenol Soluble Modulin Gene in Methicillin Resistant Staphylococcus Aureus.

BACKGROUND Staphylococcus aureus (S. aureus) is a main pathogen associated with different types of hospital acquired infections. There are various factors associated with the virulence of S. aureus. Among these factors are biofilm formation, antibiotics resistance, alpha-toxin, and phenol-soluble modulins (PSMs) which are encoded by genes within the core genome. The aims of the present study were to identify the prevalence psm-mec gene in MRSA isolated from different types of hospital acquired infections and to study the association of this gene with biofilm formation capacity in S. aureus. METHODS The study was a retrospective, cross-sectional study that included 150 isolates of MRSA isolated from different clinical samples. Methicillin resistant S. aureus was identified as resistance to cefoxitin disc by disc diffusion method, biofilm detection by microplate method, and polymerase chain reaction (PCR) was used for detection of PSMα gene. RESULTS MRSA was identified by phenotypic detection with resistance to cefoxitin disc in 64.7% of the isolated S. aureus. Biofilm formation was detected in 70 isolates (46.7%) with high titer in 61 isolates, intermediate titer in 6 isolates and low titer in 4 isolates. PSMα gene detected in 65 (43.3%) of the isolates, Table 1. There was significant association between the presence of PSMα gene and formation of biofilm (p = 0.0001). All detected PSMα genes were present in 65 (92.8%) of positive S. aureus isolates for biofilm formation. CONCLUSIONS There was high prevalence of the PSMα gene in MRSA with association with high titer biofilm forming S. aureus. The absence of PSMα gene in MRSA strains may reduce the ability of MRSA to form biofilm.