Risk factors for community-associated methicillin-resistant Staphylococcus aureus colonisation in a large metropolitan area in Greece: An epidemiological study using two case definitions.

The aim of this study was to evaluate the epidemiology and characteristics and to identify modifiable risk factors for community-associated (CA) MRSA colonisation in a region with high prevalence. A large patient population (n=2280) from two tertiary care centres in Athens (Greece) was evaluated. Demographics and potential risk factors for CA-MRSA colonisation were recorded prospectively. Presence of the Panton-Valentine Leukocidin (PVL) toxin and mecA gene was determined in all MRSA isolates. Two definitions for CA-MRSA were applied. Univariate and multivariate analyses to identify predictors of previously unknown CA-MRSA colonisation were performed. In total, 120 (5.3%) MRSA carriers were identified; in 67 the isolates were classified as CA-MRSA using criteria based on the CDC definition, compared with 35 based on a definition including PVL toxin positivity. Factors significantly associated with previously unknown CA-MRSA carriage (CDC definition) included being a child or adolescent (OR=3.6, 95% CI 1.5-8.6), belonging to the family of an index case (OR=2.4, 95% CI 1.2-4.8), and presence of any co-morbidity (OR=1.7, 95% CI 1.04-2.8) or chronic skin disease (OR=3.6, 95% CI=2.2-6.1). In multivariate analysis, presence of any co-morbidity was the only significant predictor (OR=4.9, 95% CI 1.07-22.5; P=0.04). No easily modifiable risk factor for previously unknown CA-MRSA colonisation was identified. The CDC-based epidemiological definition for CA-MRSA appears to be more sensitive in detection of CA-MRSA colonisation than a purely molecular definition based on presence of the PVL gene.