Prevalence of Methicillin Resistant Staphylococcus aureus and Minimum Inhibitory Concentration (MIC) of Vancomycin Against it in Two Selected Semi Urban Sri Lankan Communities

Background. Methicillin Resistant Staphylococcus aureus (MRSA) infection has become a major problem within the hospitals and in the community. The aim of this study was to describe the prevalence of MRSA nasal colonization in the community, antibiotic sensitivity patterns of these isolates and MICs of vancomycin. Methods. Nasal samples for Staphylococcus aureus culture and sociodemographic data were obtained from adults and children 2 years of age from the two communities. Staphylococcus aureus isolates were identified by routine laboratory methods and antimicrobial susceptibility tests were done by using the CLSI guidelines. VancomycinMICs were tested for both MRSA and Methicillin Sensitive Staphylococcus aureus (MSSA) isolates. Results. A total of 317 subjects, 88 (28 %) were positive for Staphylococcus aureus. Of the 88 isolates, 18 (5.7 %) were MRSA and 70 (22 %) were MSSA. Of the MRSA isolates the high sensitivity noted in Linezolid, Ciprofloxacin, Trimethoprim-Sulfamethoxazole, Tetracycline Rifampin and Gentamicin. Inducible Clindamycin resistance was reported 44 %, 7 % for MRSA and MSSA isolates respectively. Vancomycin MICsof all the isolates were 2g/mL. Conclusions. MRSA isolates of this study are more likely to be community acquired. However, further molecular studies are needed to confirm these findings. Both MRSA and MSSA isolates vancomycin MICs were 2g/mL. However, MRSA strains showed higher level vancomycin MIC compared to MSSA.