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

<b>Background:</b> 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. <b>Methods:</b> A retrospective analysis was conducted 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 assessed to determine the diagnostic utility of deep tissue sampling. <b>Results:</b> The overall concordance between deep tissue and bone cultures was 51.8%. <i>Staphylococcus aureus</i> 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 the cases, pathogens were isolated only from deep tissue cultures, while 16.5% had positive bone cultures but negative deep tissue cultures. <b>Conclusions:</b> Deep tissue cultures demonstrate moderate microbiological concordance with bone biopsy in the diagnosis of DFO, particularly in cases with monomicrobial <i>Staphylococcus aureus</i> infection. While bone biopsy remains the gold standard, deep tissue cultures may be a practical alternative when bone sampling is not feasible or for patients unsuitable for surgery. However, their limited reliability in detecting Gram-negative and polymicrobial infections underscores the need for more accurate, less invasive diagnostic tools. Future research should focus on validating molecular and advanced diagnostic methods to improve clinical decision-making and patient outcomes in DFO.