Prevalence of methicillin-resistant and methicillin-sensitive Staphylococcus aureus nasal colonization among patients at the time of admission to the hospital.

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is an important agent of hospital-acquired infection. The mode of entry of MRSA in the hospital might be on admission of patients with MRSA infection or nasal colonization. The present study was undertaken to determine the prevalence of MRSA nasal colonization among patients on admission to hospital.

Methods: Six hundred patients were screened for nasal colonization of MRSA on admission to hospital. Nasal swabs were cultured on salt mannitol agar and blood agar. Age, sex, previous admission to hospital and antibiotic therapy were recorded.

Results: S. aureus was isolated from the nasal swabs of 122 patients (20.2%) on admission to hospital. MRSA was isolated from 7 patients (1.1%) and methicillin-sensitive S. aureus (MSSA) from 115 patients (19.1%). Nasal colonization of S. aureus was higher in younger and elderly patients and significantly higher colonization was observed among females. The MRSA strains isolated from nasal swabs had a different antibiotic susceptibility pattern than those isolated from patients having hospital-acquired MRSA infection. Previous admissions to hospital, underlying disease antibiotic therapy were not risk factors for MRSA nasal colonization.

Conclusion: MRSA nasal colonization of patients on admission to hospital is low in this region. The screening of every new admission would not be cost effective, but patients transferred form other institutions should be screened for MRSA. Standard infection control precautions should be strictly implemented to prevent the spread and control of MRSA infections.