Prevalence of MRSA in Emergency and Elective Patients Admitted to a Vascular Surgical Unit: Implications for Antibiotic Prophylaxis

Objectives1.Audit adequacy of admission screening for MRSA in vascular surgery patients.2.Establish the prevalence of MRSA carriage at the time of admission in emergency/transfer and elective patients.3.Establish a threshold prevalence of MRSA that should trigger the use of prophylactic antibiotics active against MRSA.4.Model some of the costs and efficacy of glycopeptides such as vancomycin, compared to aminoglycosides such as gentamicin, for the prevention of MRSA surgical site infections.Materials and Methods200 consecutive emergency/transfer and 150 consecutive elective patients admitted between April 2004 and January 2005, were studied. Data was obtained from departmental Morbidity and Mortality records and the computerised laboratory medicine information system.Results261 (75%) of the 350 patients were screened for MRSA on admission (target 100%). The proportions of emergency/transfer and elective patients screened were similar (78% and 72% respectively). The prevalence of MRSA carriage detected by admission screening in emergency/transfer patients 30/153 (20%), was significantly higher (p < 0.0001) than in elective patients 2/108 (2%).A simple decision analysis model suggests that gentamicin should be used when the prevalence of MRSA reaches 10% and vancomycin when the prevalence reaches 50%.ConclusionsThe high prevalence of MRSA colonisation in emergency/transfer patients has important implications for pre-operative antibiotic prophylaxis.