rapid and accurate method for prevention and control of methicillin-resistant staphylococcus aureus in the ICU

ABSTRACT

Methicillin-resistant S. aureus [MRSA] oxacillin - resistant S. aureus [ORSA] is frequently encountered in health-care settings. Early screening for MRSA nasal colonization can identify patients requiring isolation and can be part of an effective infection control program. This study aimed to provide same-day results to facilitate rapid diagnosis and therapy MRSA to avoid hospital-acquired infections. A total of 80 patients from the medical intensive care units [ICUs] of El-Demerdash Hospital, Cairo Egypt, were screened for MRSA colonization. Two nasal swabs were collected from each patient, the first vortexed in the Liquid Stuart medium and two aliquots of 200 micro l were collected from the medium and tested. For direct culture, the 200 micro l aliquot was inoculated directly onto MRSA screening medium agar plate and incubated at 35[degree sign]C for 24-48h. The other 200 micro l aliquot was first cultured in a pre-enrichment broth medium for 24 hours at 35[degree sign]C, thereafter cultured onto MRSA screening medium agar for another 24-48 hr at 35[degree sign]C. The second swab was used to screen MRSA by a qualitative real-time PCR. Sixty six swabs [82.5%] were negative by culture and real time PCR for MRSA. Fourteen swab samples [17.5%] were positive by both methods. None was positive by culture only [0%], while the PCR assay detected additional four MRSA positive specimens [i.e 5%]. The sensitivity, specificity, positive-predictive value and negative-predictive value for PCR were 100%, 93.9%, 77.8% and 100%, respectively. Real-time PCR testing of nasal specimens can be used as a rapid and reliable technique for MRSA surveillance programs in the ICUs