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

Abstract

Objectives: In this study, it was aimed to determine the prevalence of nasal carriage of S. aureus in chronic osteomyelitis, assessed trends in methicillin resistance with time, and evaluated the bone and nasal cultures in staphylococcal chronic osteomyelitis. Materials and methods: Bone and nasal cultures were performed intra-operative and pre-operatively from 43 patients with chronic osteomyelitis. Inoculation was performed on 5% sheep blood and eosine-methylen-blue agar. The samples were incubated at 37°C for 24 hours. Catalase and coagulase tests were performed on Gram positive coccus strains. Antimicrobial susceptibilities of all S. aureus strains were evaluated by disc diffusion method according to CLSI for oxacillin and other antibiotics. Results: In this study pre-operative nasal cultures and intra-operative bone cultures obtained between May 2005 and September 2006 were evaluated retrospectively. Of the 43 nasal cultures, 31 (72%) yielded staphylococcal strain, 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 methicilline resistance. Overall the similarity rate of staphylococcal strains was 38% (11/29), while considering the status of strains resistant to antibiotics; this ratio was 24% (7/29). Conclusions: Nasal S. aureus carriage rate (58%) in patients with chronic osteomyelitis was higher than the community and the other patient groups. However, the surveillance cultures can give knowledge about the causative pathogen of 25% of the culture negative cases.