Aim: The purpose of this study was to evaluate the prevalence of methicillinresistant Staphylococcus aureus (MRSA) isolates in the Orthopaedic Department of a new University Hospital, two years from its opening. Methods: Forty-three consecutive S. aureus isolates, collected from cultures (pus 90%) from consecutive orthopaedic inpatients were included in the study. Resistance to antimicrobial agents was assessed by the disk diffusion method. The mecA-gene was detected by PCR assay, whereas molecular typing of the isolates was performed by PFGE. Results: Only 5 of the 43 strains (11.6%) expressed high level resistance to oxacillin (MIC ≥ 64mg/L). All these isolates possessed mecA-gene and exhibited resistance, except oxacillin, to more than four classes antimicrobial groups. The remaining 38 isolates (34 beta-lactamase positive) were susceptible to oxacillin (MIC ≤ 2mg/L), and expressed a less resistant type than that of MRSA. Molecular typing by PFGE showed apparent heterogeneity among isolates and the absence of predominant clones. Conclusions: The 11.6% prevalence of MRSA is well below the reported average in the literature. Apparently the isolates originated from different sources of contamination. All patients had previous hospitalizations, where they acquired the infections and subsequently transferred the MRSAs to our department. Precautions and measures taken in the wards limited the spread and dissemination of the isolates as demonstrated by the heterogeneity and the absence of predominant clones. These þndings further reiterate the value of the low-cost, standard preventive procedures to control nosocomial infections in a high-risk orthopaedic department.

Purpose: The purpose of this study was to evaluate the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) isolates in the Orthopaedic Department of a new University Hospital, two years from its opening.

Material and Methods: Forty-three consecutive S. aureus isolates, collected from cultures (pus 90%) from consecutive orthopaedic inpatients were included in the study. Resistance to antimicrobial agents was assessed by the disk diffusion method. The mecA-gene was detected by PCR assay, whereas molecular typing of the isolates was performed by PFGE.

Results: Only 5 of the 43 strains (11.6%) expressed high level resistance to oxacillin (MIC ≥ 64mg/L). All these isolates possessed mecA-gene and exhibited resistance, except oxacillin, to more than four classes antimicrobial groups. The remaining 38 isolates (34 beta-lactamase positive) were susceptible to oxacillin (MIC ≤ 2mg/D, and expressed a less resistant type than that of MRSA. Molecular typing by PFGE showed apparent heterogeneity among isolates and the absence of predominant clones. Conclusions: The 11.6% prevalence of MRSA is well below the reported average in the literature. Apparently the isolates originated from different sources of contamination. All patients had previous hospitalizations, where they acquired the infections and subsequently transferred the MRSAs to our department.

Precautions and measures taken in the wards limited the spread and dissemination of the isolates as demonstrated by the heterogeneity and the absence of predominant clones. These findings further reiterate the value of the low-cost, standard preventive procedures to control nosocomial infections in a high-risk orthopaedic department.