Effect of bone biopsy in guiding antimicrobial therapy for osteomyelitis complicating open wounds

Background: Osteomyelitis associated with infected overlying wounds represents a difficult diagnostic and therapeutic problem; bone biopsies can be done during debridement of the overlying wounds, but it is unclear how often the results of these bone cultures actually affect subsequent antibiotic decisions. The present study was undertaken to evaluate the usefulness of bone biopsies in guiding antibiotic therapy for this type of osteomyelitis. Methods: Culture results of 44 bone biopsies taken during surgical debridement in 41 patients over the period from lune 1994 to August 1998 were compared with those from the overlying wounds to determine whether the data affected the subsequent choice of antibiotics. The study design was that of a retrospective chart review in which the standard operative and microbiological procedures in place at the Milwaukee Veterans Affairs Medical Center were used. Results: Sixty-one wound and 55 bone isolates were obtained during this study. Thirty-one isolates were found in bone, but not the overlying wound; diphtheroids were the most common organism obtained in this fashion. Correlation between wound and bone isolates was generally poor. Antibiotics were subsequently changed in 20 of the 44 cases after results of the bone biopsy became known, with the bone isolates already being covered in 10 cases and the bone biopsy results ignored in 14 cases. Conclusion: Because bone biopsy results seem to aid in tailoring antibiotic therapy in almost half the cases when bone is sampled during wound debridement surgery, this technique may be very helpful in certain cases and should be regularly undertaken when these procedures are carried out.