Purpose: To determine the prevalence and to identify risk factors of MRSA colonization, among patients presenting for hospital admission.Methods: In a tertiary teaching hospital, surveillance cultures from the nares, axillae and inguinal areas were performed at the time of admission for all patients except those admitted in the oncology and hematology unit. Demographic and possible risk factors for colonization were recorded. Antibiotic susceptibility was tested with standard methods and methicillin resistance by the cefoxitin disc method and mec gene detection. Isolates were characterized as CA-MRSA according to their susceptibility pattern. MRSA isolates were tested for Panton Valentine leukocidin (pvl) gene.Results: Swab samples were collected from 2994 patients presenting for admission in two years. Mean patient age was 53 years (median 52) and the female to male ratio of 1.3:1. Staphylococcus aureus was isolated from 473 (15.8%) patients and MRSA from 88 (3%) of the patients (18.8% of colonizing isolates).Detection of colonization was (442/473) 93.4% in the nares, (128/279) 45.9% in the axilla and (157/279) 56.3% in the inguinal area. All the colonizing MRSA isolates, excluding three, exhibited in their sensitivity tests the pattern expected for CA-MRSA with the majority of them sensitive to cotrimoxazole, clindamycin, minocycline, rifampin and quinolones. Interestingly tetracycline and fucidic acid were inactive in the majority of strains. 64 MRSA isolates were tested for Pantone Valentine Leukocidin and 36 (56.25%) were positive. In the multivariate analysis comparing MRSA-colonized to MSSA-colonized or non-colonized patients, independent predictors of MRSA colonization were: residence at long term care facility (LTCF) (P <0.001, OR 12.05) and the presence of skin disease (p<0.001, OR 3.06)Conclusion: Colonization with MRSA of patients admitted to the hospital is low and appears to reflect the prevalence of colonization with CA-MRSA in the community. Risk factors for MRSA acquisition do not include previous contact with health-care facilities but instead the presence of skin diseases (affecting skin integrity) and residence in long term care facility.
Panton–Valentine leukocidin-positive methicillin-resistant Staphylococcus aureus outbreak among healthcare workers in a long-term care facility
