Long-term MRSA carriage in hospital patients.

A retrospective study was performed to determine the frequency of and risk factors for long-term carriage of methicillin-resistant Staphylococcus aureus amongst 79 patients who initially acquired MRSA during hospital admission and were re-admitted at least once during the study period (28 months in total). Of the 52 patients who were re-screened during their re-admissions, 33 (63%) had positive MRSA screens on at least one re-screening and 19 (37%) had all negative screens. Patients whose case notes had been tagged were more likely to have screens performed. Of the potential risk factors assessed, only the presence of skin lesions significantly increased the risk of prolonged MRSA carriage (P = 0.032). Evaluation of the effect of anti-MRSA eradication treatment showed that patients who were subsequently MRSA negative on all re-admissions were more likely to have received some form of anti-MRSA treatment than those who remained positive on at least one re-admission (P = 0.048). The results show that the strain of MRSA at our hospitals (predominantly EMRSA 15) is associated with prolonged carriage in certain patients and that attempts at eradication often do not affect the duration of carriage. This has infection control implications for the management of known MRSA positive patients re-admitted to hospital. Copyright 2000 The Hospital Infection Society.