A community-based study on nasal carriage of Staphylococcus aureus

Community acquired methicillin resistant Staphylococcus aureus (CA-MRSA) is a major global problem. Colonization rates of MRSA in the community have been reported to range from 0 to 9.2 per cent. The present study was conducted to detect S. aureus nasal colonization and prevalence of MRSA in children (5 to 15 yr) in an Indian community setting of rural, urban and semiurban slums, as also evaluation of an in-house PCR to detect MRSA.

Nasal swabs from children were cultured and S. aureus isolates were processed for antibiotic susceptibility. mecA gene was studied by polymerase chain reaction (PCR) on S. aureus isolates and directly from enrichment broth aliquots inoculated with nasal swabs, at sequential time intervals.

The overall prevalence of S. aureus nasal colonization was 52.3 per cent and that of MRSA 3.89 per cent. CA-MRSA nasal carriage was 3.16 per cent in children without prior exposure to health care settings. PCR detection directly on nasal swabs and enrichment broth had a poor sensitivity of 60.42 per cent.

There was a high rate of S. aureus nasal colonization in the 5-15 yr age group and an alarming rate (3.89%) of community acquired methicillin resistant S. aureus nasal colonization in the community. PCR as a method of direct detection of MRSA from nasal samples needs further fine tuning.