Prevalence of Gram Negative Bacteria in Diabetic Foot -A Clinico-Microbiological Study

Aim and Objective: To determine the bacterial spectrum in diabetic foot lesions and analyze the antibiotic susceptibility pattern of the isolated bacteria. Methods and Methodology: Tissue samples/discharge/pus/ were cultured from 202 patients admitted for the treatment of diabetic foot infections. Specimens were tested by gram stain, culture and antibiotic sensitivity. Results: A total of 202 specimens were cultured, yielding 246 bacteria at the end of 18-24hrs. Gram negative aerobes were the most frequently isolated bacteria constituting 162 isolates (66%), followed by grampositive aerobes 78 isolates (32%). Enterobacteriaceae group and P. aeruginosa strains were largely susceptible to imipenem (100%), piperacillin-tazobactam, ceftazidime, aminoglycosides, and ciprofloxacin. More than 70% of staphylococcus aureus was sensitive to methicillin. Cefoperazone + sulbactum showed about 67% sensitivity, while ciprofloxacin and amikacin were only 23% and 44% sensitive. MRSA was isolated in 20 cases (47% of S.aureus) and Methicillin resistant coagulase negative staphylococcus in 2 cases (15% of coagulase negative staphylococcus). Methicillin resistant organisms were sensitive to vancomycin (95%). Conclusion: Diabetic foot infections are predominantly due to gram positive bacteria like Staphylococcus aureus or polymicrobial. There is a growing trend of isolating gram negative bacteria in these naïve lesions of the diabetic foot. The need for adequate gram negative antibacterial coverage at the commencement of diabetic foot therapy is essential to prevent and treat limb/life threatening infections.