Systematic Review and Meta-Analysis of the Diagnostic Accuracy of Swab Cultures Versus Tissue Biopsy for the Diagnosis of Diabetic Foot Infections

To evaluate and compare the diagnostic accuracy of swab cultures versus tissue biopsy in identifying pathogens causing infection in patients with diabetic foot, and to assess the agreement between microbiological results. To compare sensitivity, specificity, and overall diagnostic performance of swab cultures versus biopsy, using tissue biopsy as the reference standard in infected diabetic foot wounds. A systematic review and meta-analysis were performed based on searches in CINAHL, Embase, and PubMed, including studies from database inception to April 9, 2025. Studies comparing diagnostic accuracy or lists of pathogens identified by swab and tissue biopsy in adult patients with diabetic foot infection were included. A random-effects diagnostic accuracy meta-analysis was conducted. Seventeen studies including 1,581 participants met inclusion criteria. Swab cultures identified 765 gram-positive pathogens compared with 875 detected by tissue biopsy, and 457 gram-negative pathogens compared with 452 identified by biopsy. The three most prevalent species were Staphylococcus aureus (∼12.0%), Streptococcus spp. (∼5.0%), and Enterococcus spp. (∼4–5%). Concordance rates for microbial species identified by swab and biopsy showed high heterogeneity, ranging from 25% to 90%. Five studies provided sufficient data and were included in the meta-analysis. Pooled sensitivity and specificity of swab cultures for detecting diabetic foot infection were 84.8% and 68.0%, respectively, using tissue biopsy as the reference standard. Subgroup analyses showed higher pooled sensitivity and specificity for gram-negative pathogens (85.2% and 92.9%, respectively) compared with gram-positives (76.8% and 81.0%, respectively). Swab cultures show good diagnostic performance for identifying gram-negative pathogens and may be considered acceptable for detecting gram-positive pathogens. Although tissue biopsy remains the reference standard, swab sampling can be a feasible alternative in resource-limited settings, in superficial infections, or when biopsy is contraindicated due to local restrictions.