Virulence factors evaluation in methicillin-sensitive and methicillin-resistant Staphylococcus aureus isolated from children referred to Tehran Children's Medical Center Hospital

Staphylococcus is a bacterium responsible for a wide range of diseases, from mild skin infections to lethal necrosis pneumonia. The aim of this study was to determine the virulence factors among methicillin resistant and sensitive strains isolated from clinical specimens of children referred to the pediatric medical center and also to be aware of their antibiotic resistance.
In the present study, 100 strains of Staphylococcus aureus, susceptible and resistant to methicillin, were collected during one year. First Biochemical tests were performed to detect Staphylococcus aureus bacteria. Then antibiotic susceptibility test was performed using antibiotic disks (MAST;England) according to CLSI guidelines. The presence of hlg, mecA, nuc and pvl genes was investigated by PCR method and sequenced.
30 samples (30%) were methicillin-resistant (MRSA) using the cefoxitin disk. The most susceptible to antibiotics, vancomycin with 100% and the highest resistance to antibiotics, penicillin with 98% were determined. The prevalence of hlg, mecA, and pvl genes was 30%, 95% and 6%, respectively.
The present study showed that vancomycin and cotrimoxazole antibiotics were the best effect against MRSA strains.