A study of evaluation of wound swab for bacteriological culture and antibiotic sensitivity in comparison with tissue sample culture in diabetic patients with infected foot ulcer

Background: Most diabetic wounds are infected and eradication of the infected source is paramount to the success of healing. Antibiotic culture and sensitivity of samples aid in the assessment of the severity of the infection and the state of sensitivity or resistance of organisms in an infected ulcer to antibiotic treatment, thereby preventing or minimizing the necessity of amputation. Aims: To compare two methods of evaluating bacterial infection, wound swab culture (SC) against tissue sample cultures (TC), and determine sensitivity patterns and compare them for establishing the diagnosis of infected diabetic foot ulcers. Methods and Material: New-onset diabetic foot ulcers were subjected to tissue sampling and wound swabbing; specimens were cultured for aerobic and anaerobic organisms. a. Settings and Design: Prospective observational study at a tertiary care hospital done over two years. b. Statistical analysis used: Data was recorded in excel data sheet and statistically analysed by using the SPSS Ver 22.0. Results: Three hundred and eight micro-organisms were isolated from a cumulative total of 127 infected wounds (2.75 and 2.08 per wound for SC and TC, respectively). Sensitivity and specificity were 82.27% vs 78.48% and 71.43% vs 52.38% for the SC and TC groups, respectively. The maximum concordance was noted in the Grade 2 ulcer group (73.84%). Conclusion: Wound SCs were comparable to TCs for Grade 2 ulcers. For higher grades of ulcers, tissue sampling method is recommended.