Methicillin-resistant Staphylococcus aureus (MRSA) Infection in the Elderly

From April 1991 to March 1992, there were 117 elderly persons whose materials were examined for a bacterial culture in various clinical aspects. They consisted of 74 inpatients and 23 outpatients in a geriatric hospital, and 20 residents of a nursing home. The retrospective study was carried out in order to evaluate the various factors which may influence the occurence of methicillin-resistant Staphylococcus aureus (MRSA) infection in the elderly. The positive rate of MRSA was significantly greater for the inpatients (27.0%) than for the outpatients (0.0%) and the residents of a nursing home (5.0%). Compared to the MRSA negative inpatients, the MRSA positive inpatients had a lower ADL score (0.3*0.7 vs 1.4*1.2, p<0.05) and a larger amount of antibiotics prior to the bacterial culture (1.8*1.4 vs 0.8*1.3, p<0.05). After controlling for the confounding effects of age, length of hospitalization, ADL score and the administration of antibiotics, the risk of MRSA infection among the inpatients was increased in patients who could not either take meals, walk or use restroom by themselves (OR 2.24, 95% Cl 1.22-4.10) and in patients undergoing antibiotic therapy (OR 1.88, 95% Cl 1.03-3.44). In the elderly population, the disability to perform ADL seems to be one of the most important risk factor for MRSA infection. J Epidemiol, 1993; 3 : 117-120.