The evaluation of staphylococci strains isolated from nasal and bone cultures in patients with chronic osteomyelitis

Objectives: In this study, it was aimed to determine theprevalence of nasal carriage of S. aureus in chronic osteomyelitis,assessed trends in methicillin resistance withtime, and evaluated the bone and nasal cultures in staphylococcalchronic osteomyelitis.Materials and methods: Bone and nasal cultures wereperformed intra-operative and pre-operatively from 43patients with chronic osteomyelitis. Inoculation was performedon 5% sheep blood and eosine-methylen-blueagar. The samples were incubated at 37°C for 24 hours.Catalase and coagulase tests were performed on Grampositive coccus strains. Antimicrobial susceptibilities of allS. aureus strains were evaluated by disc diffusion methodaccording to CLSI for oxacillin and other antibiotics.Results: In this study pre-operative nasal cultures andintra-operative bone cultures obtained between May 2005and September 2006 were evaluated retrospectively. Ofthe 43 nasal cultures, 31 (72%) yielded staphylococcalstrain, of these 18 (58%) were S. aureus. Of the 18 S.aureus strains, 13 (72.2%) have methicilline resistance.On the other hand, of the 43 bone cultures, 29 (67.4%)yielded staphylococci strain, of these 23 (79.3%) were S.aureus. Of the 23 S. aureus strains, 52.1% have methicillineresistance. Overall the similarity rate of staphylococcalstrains was 38% (11/29), while considering the statusof strains resistant to antibiotics; this ratio was 24% (7/29).Conclusions: Nasal S. aureus carriage rate (58%) in patientswith chronic osteomyelitis was higher than the communityand the other patient groups. However, the surveillancecultures can give knowledge about the causativepathogen of 25% of the culture negative cases.Key words: Chronic osteomyelitis, nasal carriage, Staphylococcusaureus, bone culture