Objective: This study aimed to assess the microbiological concordance between swab and soft tissue cultures, and corresponding bone specimen cultures from patients with diabetic foot osteomyelitis (DFO). We aimed to analyze the bone specimens’ antimicrobial susceptibilities, and to improve clinical management of diabetic foot ulcer infections by using proper antibiotics.
Methods: The microbial culture results of ulcer swabs, and soft tissue and bone tissue specimens, and the antimicrobial susceptibility tests of bone specimens from patients with DFO were analyzed in a single diabetic foot center.
Results: A total of 60 patients with results from three specimens were included. Staphylococcus aureus  was the most common bacterium isolated from the three specimens. The microbiological results for the three specimens were identical in 12 cases, the culture results from swabs and bone tissue specimens were identical in 14 cases, and the results from soft tissue and bone tissue were identical in 46 cases. The concordance of the results of pathogens isolated between soft tissue and bone specimen cultures was higher than that between the swab and bone cultures. Gram-positive bacteria were more sensitive to moxifloxacin, linezolid, and vancomycin, while Gram-negative bacteria were more sensitive to piperacillin/tazobactam, cefoperazone/sulbactam, and carbapenems.
Conclusion: Soft tissue culture results have more reliable microbiological concordance to identify DFO bacteria than swab culture results and targeted antibiotic therapy for DFO should be based on antimicrobial susceptibility testing in bone tissue specimen cultures.
Keywords: diabetic foot osteomyelitis, ulcer swabbing, microbiological concordance, antimicrobial susceptibility test, targeted antibiotic therapy