Study of fine-needle aspiration microbiology versus wound swab for bacterial isolation in diabetic foot infections.

Background & Objectives: Proper identification of the infection causing microbe in diabetic foot infections (DFIs) is essential for starting appropriate treatment. The objectives of this study were to compare fine-needle aspiration microbiology (FNAM) with wound swab as methods of sample collection in isolating microorganisms causing DFIs and also to compare the microbiological profile and sensitivity pattern of the infecting organisms.

Methods: This study was conducted targeting all consecutive patients with DFIs with perfusion, extent, depth, infection and sensation (PEDIS) grade 2, 3, and 4 infections admitted in the department of Surgery of a tertiary care hospital in south India during July to August 2017. A superficial wound swab and an FNAM were collected from all the patients. These swabs are analyzed using standard microbiological techniques.

Results: Eighty patients with DFI were included. Bacterial culture using FNAM samples yielded growth in 58.75 per cent samples, whereas wound swab samples yielded growth in 93.8 per cent cultures done. Measure of agreement between the two techniques using Kappa statistics was 0.069 (P=0.28).

Interpretation & Conclusions: In diabetic wound infections, wound swabs were sufficient to identify organisms in all grades of infection. However, in deeper infections (grade 3 and 4), FNAM would be a reliable investigation than wound swab.