Consideration of age at admission for selective screening to identify methicillin-resistant Staphylococcus aureus carriers to control dissemination in a medical ward

Background Methicillin-resistant Staphylococcus aureus (MRSA) has become an increasingly important pathogen responsible for hospital-acquired infections. Our study was to evaluate the efficiency of our selective screening program for methicillin-resistant Staphylococcus aureus (MRSA) carriers at admission to nonintensive care units. Methods During 6 months, all patients were screened at admission to an internal medicine ward, at which time they were classified as patients at risk of carriage (PRC) and those with no known risk factor. The amplitude of cross transmission was estimated using various indicators during this universal screening period and during the same calendar period of the preceding year (selective screening). Results The prevalence of MRSA carriage at admission was 5.5%. Among the 22 carriers identified, only 10 were PRC. Age >80 years was significantly associated with MRSA carriage upon admission (OR, 3.5; P < .01). All estimation indicators of MRSA dissemination amplitude were significantly lower during universal screening (relative risks varied from 2.79 to 26.4 according to indicators), demonstrating the need to broaden our criteria defining PRC. Conclusion Adding patients >80 years of age to our PRC definition would increase screening sensitivity (15 carriers identified for 128 patients sampled) and would enable early implementation of barrier precautions for the additional carriers identified.