218-OR: Does Antibiotic Treatment before Bone Biopsy Affect the Identification of Bacterial Pathogens from Bone Culture?

Our aim was to evaluate the effect of antibiotic exposure on bacterial pathogen yield in patients with diabetic foot osteomyelitis. In a retrospective cohort study, we evaluated 142 patients admitted to the hospital with diabetic foot osteomyelitis which confirmed by histologic evaluation. Histologic criteria for osteomyelitis included the presence of an inflammatory response, bone necrosis, and/or bone fragmentation. We compared bacterial pathogens in patients that received antibiotics before bone culture (n=114) and patients that did not receive antibiotics (n=28), as well as bacterial yield based on the duration of antibiotic exposure. We used the chi square test to compare antibiotic exposure and culture yield. There was not a significant difference in culture yield in patients that received antibiotics (77.9%) and patients that did not (85.7%, p=0.58). There was no difference in patients that received antibiotics for ≥4 days (n=56, 71.4%), 1-3 days (n=58, 84.5%) and no antibiotics (85.7%, p=0.15). In conclusion, the results of bacterial recovery were similar in patients regardless of the length of antibiotic treatment. Antibiotic exposure did not change the bacterial yield, the type of bacteria or the number of bacteria. In patients with suspected diabetic foot osteomyelitis, there is no evidence to support withholding antibiotics prior to obtaining a bone biopsy.