Background: The microbiology of the diabetic foot is complex, making swab culture controversial; biopsy culture is the gold standard.
Objective: To determine the diagnostic utility of swab culture in diabetic foot ulcers.
Methods: Comparative study of diagnostic utility. Diabetic foot ulcers were classified according to the University of Texas scale. Cultures by biopsy and swabbing were performed. Bacterial identification was performed by standard biochemical methods. Antimicrobial susceptibility was determined by the plate diffusion method. An analysis of the diagnostic test was made, reporting descriptive measures of frequencies.
Results: We obtained specimens for culture from 118 patients. Grade II and III lesions were the most frequently occurring (80%). Overall, 132 organisms were isolated from biopsies and 118 from swabs, with those of the Enterobacteriaceae family being the most frequent (56% from biopsies and 60% from swabs). Swab culture had a calculated sensitivity of 0.85, specificity of 0.86, positive predictive value of 0.98, negative predictive value of 0.43, positive likelihood ratio of 5.9, and negative likelihood ratio of 0.2.
Conclusion: Swab culture is a reasonable option to determine the diabetic foot microbiology.