Are Deep Tissue Cultures a Reliable Alternative to Bone Biopsy for Diagnosing Diabetic Foot Osteomyelitis? A Comparative Diagnostic Study

Background: Diabetic foot osteomyelitis (DFO) is a serious complication of diabetic foot ulcers (DFUs) that contributes to high morbidity and an increased risk of lower extremity amputation. While bone biopsy cultures are considered the gold standard for identifying causative pathogens, their invasive nature limits widespread clinical use. This study evaluates the microbiological concordance between deep tissue and bone cultures in diagnosing DFO. Methods: A retrospective analysis was con-ducted on 107 patients with DFO who underwent simultaneous deep tissue and bone biopsy cultures. Patient demographics, ulcer classification, and microbiological culture results were recorded. The agreement between deep tissue and bone cultures was as-sessed to determine the diagnostic utility of deep tissue sampling. Results: The overall concordance between deep tissue and bone cultures was 51.8%. Staphylococcus aureus was the most frequently isolated pathogen in both culture types and had the highest agreement rate (44.4%). Concordance rates were lower for Gram-negative bacteria (31.9%) and other Gram-positive microorganisms (24.2%). In 21.2% of cases, patho-gens were isolated only from deep tissue cultures, while 16.5% had positive bone cul-tures but negative deep tissue cultures. Conclusions: Deep tissue cultures demonstrate moderate agreement with bone biopsy cultures when diagnosing DFO, particularly for Staphylococcus aureus. While bone biopsy remains the gold standard diagnosis tool, deep tissue cultures may provide clinically useful information when bone sampling is not feasible. Further studies are needed to improve non-invasive diagnostic methods for DFO.