Indian Journal of Microbiology Research

One of the major risk factors for the nosocomial infection among the hospital population was identified as the nasal carriage of Staphylococcus aureus and Methicillin-Resistant Staphylococcus aureus (MRSA). This study was aimed to find the prevalence and factors associated with nasal carriage of S. aureus and MRSA among patients in a tertiary care hospital.

A cross sectional study was designed for S. aureus and MRSA nasal carriage. History of factors for S. aureus and MRSA colonisation was collected using a questionnaire. A total of 750 specimens were streaked directly onto mannitol salt agar. S. aureus was identified and antibiotic susceptibility test was done. All MRSA isolates were subjected to polymerase chain reaction (PCR).

Among the total specimens collected, S. aureus isolated were 115 (15%). Out of this 115 isolates, only 5 were found to be MRSA (4.3%). The overall MRSA nasal carriage rate was only 0.6% (5/750). PCR done for all the MRSA isolates showed positive results for Type III SCC mec gene and negative results for Panton Valentine leukocidin gene indicating that they belong to Hospital Acquired MRSA (HA-MRSA). Majority of the patients with MRSA nasal colonisation had no history of hospitalisation, or other factors contributing to colonisation from hospital environment.

S. aureus nasal carriage rate was 15% and the MRSA nasal carriage rate was only 0.6%. Association was not found between S. aureus or MRSA nasal colonization with factors such as previous hospitalisation, antibiotics, infections on skin and soft tissues, use of alcohol and smoking.