Methicillin-resistant Staphylococcus aureus in surgical patients: identification of high-risk populations for the development of targeted screening programmes.

INTRODUCTION: Methicillin-resistant Staphylococcus aureus (MRSA)-related hospital-acquired infection (HAI) in surgical patients is associated with high morbidity, mortality and financial cost. The identification and characterisation of populations of patients who are at high risk of developing MRSA infection or colonisation could inform the design of more effective strategies to prevent HAIs and reduce transmission of MRSA.

PATIENTS AND METHODS: An analysis of historical discharge data for the whole of 2005 (7145 surgical in-patients) was performed, for all patients admitted to general surgery at the Royal Infirmary of Edinburgh. Analysis specifically focused on MRSA laboratory data and coding data for patient demographics, medical co-morbidities, and progress of in-patient stay.

RESULTS: A total of 134 (1.88%) individual patients with colonisation or infection by MRSA were identified from indicated laboratory testing. Univariate analysis identified a significant association of concurrent MRSA-positive status with patients aged over 60 years (P < 0.01), a duration of inpatient stay > 7 days (P < 0.01), presence of a malignant neoplasm (P < 0.01), circulatory disease (P < 0.01), respiratory disease (P < 0.01), central nervous system disease (P < 0.01), renal failure (P < 0.01), and concurrent admission to ITU/HDU (P < 0.01). Multivariate analysis suggested MRSA colonisation or infection was strongest in those with co-morbid malignancy (P < 0.0001) or admission to ITU/HDU (P < 0.0001).

CONCLUSIONS: This large observational study has identified cancer patients as a UK surgical patient subpopulation which is at significantly higher risk of colonisation by MRSA. These data could inform the development of focused hospital in-patient screening protocols and provide a means to stratify patient risk.