Prevalence of oral methicillin-resistant Staphylococcus aureus in an institutionalized veterans population.

Methicillin-resistant Staphylococcus aureus (MRSA) is a nosocomial pathogen now of great concern in nursing homes and other institutional settings. MRSA has been well-documented to inhabit the nares, skin wounds, and respiratory tract, but little is known about its presence in the oral cavity. In this study, all patients admitted to an 80-bed VA extended care facility were cultured weekly for 12 weeks to detect the presence of MRSA in the nares, wounds, in-dwelling devices, and the oral cavity. Of a total of 107 participating subjects, 20 cultured positive for oral MRSA, yielding a prevalence of 18.7%, compared with 19.6% prevalence in the nares--the traditionally accepted screening site for MRSA. There was a 91.6% agreement between oral and nasal carriage in subjects, but four of 107 subjects (3.7%) cultured positive for oral MRSA without evidence of nasal carriage. These results suggest that oral MRSA may be more common than previously thought in high-risk settings, with a prevalence comparable with that of nasal infection. Further investigation is necessary to characterize the factors associated with the presence of MRSA in the oral cavity.