Prevalence and acquisition rate of methicillin resistant Staphylococcus aureus (MRSA) in internal medicine wards at the University Hospital of Geneva (HUG)

Results Among 1967 patients, swabs were collected in 1740 (88%) at admission and 712 (36%) at discharge; with 687 (35%) having both. Mean age was 64 years; 58% were male. 4.8% (84/1740) of patients were MRSA positive on admission, of which 79% -for whom data were available (43/54)had been MRSA positive on screening in the previous 6 months. Of patients who were not MRSA positive at admission, 5.8% (29/496) had previous carriage. MRSA carriage at admission was associated with age (p=0.0016, Wilcoxon rank sum test) and a positive MRSA swab in the previous 6 months (c 233, p<0.0001). 3.8% (27/710) of patients acquired MRSA during hospital stay having a positive MRSA swab on discharge but not on admission. By Wilcoxon rank sum test, MRSA acquisition was associated with length of hospital stay (p=0.0009) and age (p=0.0087). No association was found between MRSA carriage or acquisition and sex, provenance, antibiotic use, requirement of intensive or high dependency care and type of medical ward.