A clinicomicrobial study of diabetic foot ulcer infections in South India

Background: Approximately 85% of all diabetes-related lower-extremity amputations are preceded by foot ulcers. Diabetic foot ulcers are at high risk of infection secondary to high glucose levels and poor tissue perfusion. Aims of the Study: To identify the microbial pathogens and the antimicrobial sensitivity pattern of the bacterial isolates involved in the different grades of diabetic foot ulcers. Materials and Methods: Pus samples from 104 diabetic foot ulcers were processed for aerobic, anaerobic, and fungal culture. Antimicrobial sensitivity was performed as per clinical and laboratory Standards Institute guidelines. Results: Aerobic (81.66%), anaerobic (14.79%), and fungal (3.55%) isolates were obtained on culture with Gram-negative bacilli (78.98%) being isolated more than the Gram-positive cocci (21.01%). Proteus mirabilis was the most common isolate (26.08%) while Bacteroides fragilis and Peptococcus sp. were the common anaerobes obtained. 56.73% of patients had polymicrobial infection, and 23.08% of staphylococci were methicillin resistant Staphylococcus aureus. In hospitalized patients and amputees, infections were often polymicrobial (74.32%) involving anaerobic and fungal pathogens. Multi-drug resistance was seen in 28.26% of isolates. Conclusion: Our study showed polymicrobial diabetic foot infections. The isolation pattern varied according to the grade of ulcer with S. aureus being predominant in Wagner I diabetic foot and Gram-negative organisms and anaerobes being isolated as the foot grade advanced to gangrene. Management of early stages includes treatment with oral quinolones/cloxacillin/cephalosporins. Imipenem monotherapy or third-generation cephalosporins with beta lactamase inhibitors plus an anti-anaerobe drug are regimens that can be used for the advanced stage of the disease.