Meticillin resistance in orthopaedic coagulase-negative staphylococcal infections.

Orthopaedic infections due to coagulase-negative staphylococci (CoNS) and meticillin-resistant strains may be increasing. We assessed secular trends of CoNS infections and factors associated with meticillin resistance by performing a 13-year retrospective cohort study of orthopaedic patients with CoNS infections from January 1995 to December 2007. Of 60 CoNS infections, 57 (95%) were implant-related. Median follow-up after end of treatment was 5.1 years (range: 2.4-13.8). During the study period, 44,237 orthopaedic procedures were performed, 21,299 (48%) with implants. The overall cumulative incidence of CoNS-associated infection was 0.14% and 0.28% for implant-related procedures. There were non-significant changes in the absolute number or cumulative incidence of CoNS infection (chi-squared test, P values for trend: 0.45 and 0.97, respectively). Forty-five episodes (75%) were due to meticillin-resistant strains. The proportion of meticillin resistance remained stable over time (P for trend: 0.65). Whereas few (4/15) meticillin-susceptible strains were associated with prior prophylaxis that covered the causative pathogen, 28/45 meticillin-resistant strains were associated with inadequate prophylaxis (P=0.03). The cumulative incidence of orthopaedic CoNS infection is low and stable in our institution and almost exclusively implant-related. The proportion of meticillin resistance among CoNS has remained stable over the last decade with a favourable clinical outcome.