Microbiological study of diabetic foot infections

Background: Diabetic foot infections are one of the most feared complications of diabetes. This study was undertaken to determine the common aetiological agents of diabetic foot infections and their in vitro antibiotic susceptibility. Methods: A prospective study was performed over a period of one year in a tertiary care hospital. The aerobic bacterial agents were isolated and their antibiotic susceptibility pattern was determined. Members of Enterobacteriaceae were tested for extended spectrum beta-lactamase (ESBL) production by combination disc method and staphylococcal isolates were tested for susceptibility to oxacillin by screen agar method. Results: Klebsiella pneumoniae (20.5%), Pseudomonas aeruginosa (17%), Staphylococcus aureus (17%) and Escherichia coli (14.6%) were the most common aetiological agents. Polymicrobial infection was observed in 52% patients. The members of Enterobacteriaceae as well as Pseudomonas spp. and Acinetobacter spp. were found to be susceptible mainly to amikacin, piperacillin-tazobactam and imipenem. Staphylococcus aureus and Enterococcus spp. were susceptible mostly to vancomycin, with varying susceptibility to tetracycline. 56% of the isolates belonging to Enterobacteriaceae were producing ESBL and 65.5% of Staphylococcus aureus were methicillin-resistant. Conclusion: High prevalence of multi-drug resistant pathogens was observed. Amikacin, piperacillintazobactam, imipenem were active against gram-negative bacilli, while vancomycin was found to be active against gram-positive bacteria.