Risk factors for methicillin-resistant Staphylococcus aureus colonization in a geriatric rehabilitation hospital.

Background: Knowledge of the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) colonization, and the frequency of transmission is vital for the implementation of MRSA infection control measures in hospitals. We assessed risk factors for and rates of colonization of MRSA upon admission to a geriatric rehabilitation hospital, and studied the contribution of the colonization on hospital mortality.

Methods: This was a prospective study conducted over a 6-month period. All patients were screened at admission, using nasal and throat swabs. Whenever necessary, blood, sputum, urine, or wound cultures were obtained. Data collected on admission included age, sex, functional status, reasons for admission to the rehabilitation unit, previous hospitalizations, known carriage or infection with MRSA in previous hospitalizations, underlying diseases, prescribed antibiotics in previous hospitalization, serum albumin, creatinine clearance, and patient management data. Risk factors for MRSA carriage on admission were estimated by using multivariate analysis.

Results: Of the 337 patients admitted during the study period, 24 (7.1%) had a MRSA isolate, and 87.4% of these were detected through screening specimens only. Of the 24 positive admissions with MRSA, 23 (95.8%) were newly identified MRSA carriers. In the multivariate analysis, the following variables were highly associated with MRSA carriage: presence of tracheotomy (p =.0001), hospitalization for deconditioning (p =.007), renal failure (p =.039), and quinolone use prior to hospitalization (p =.037). The morbidity associated with MRSA was very low, and length of stay was not influenced by carriage.

Conclusion: The prevalence of MRSA carriage on admission to geriatric rehabilitation hospitals is high. Screening on admission is probably useful, as it detects almost all MRSA carriers. However, given the low morbidity associated with MRSA observed in this study, eradication of the MRSA carrier state is questionable. Further studies are needed to determine the usefulness and cost/benefit ratio of screening.