Clonal dissemination of mupirocin-resistant staphylococci in Greek hospitals

Objectives: To determine the rates of mupirocin resistance in staphylococci during a 4 year period (1999-2002) in Greece. Materials: A total of 1200 Staphylococcus aureus and 2760 coagulase-negative staphylococci (CoNS), consecutively collected from four Greek hospitals located in different geographical areas, were tested for susceptibility to mupirocin using the Etest and a reference agar dilution method. Results: Twenty-four S. aureus (2%) and 532 CoNS (19.2%) were found to be mupirocin-resistant during the study period. High-level mupirocin resistance was detected in 20 S. aureus (1.6%) and in 440 CoNS (15.9%), respectively. No variations in the rates of mupirocin-resistant S. aureus in relation to the year of collection were observed. In contrast, the rate of mupirocin-resistant CoNS increased dramatically from 9% in 1999, to 14% in 2000, 20% in 2001 and reached 33% in 2002. PFGE analysis revealed the presence of one main clone (A) among mupirocin-resistant S. aureus and two main clones (i and a) among Staphylococcus epidermidis isolates. Conclusions: In Greece, the rate of mupirocin-resistant S. aureus has remained low and steady since 1999. The high rate of mupirocin-resistant CoNS (33%) in 2002 was due mainly to clonal dissemination of epidemic hospital clones.