Bacterial species and antimicrobial susceptibility of wound culture, obtained from diabetic gangrene patients who went limb amputation at a Japanese university hospital

Background: Numbers of patients with diabetic gangrene is increasing. Antimicrobial treatment is commonly used, however, limb amputation cannot be avoided in severe cases. For prophylaxis at operation, basic antimicrobial agents such as cefazolin are often administrated, however, severe infection could occur if resistant strains were cultured especially in immunosuppressive patients such as diabetes. The purpose of this study is to clarify bacterial species and their susceptibility to antimicrobial agents for patients of diabetic foot gangrene. Methods & Materials: Twenty-four patients (nine females) who had amputation on their legs for treating diabetic gangrene were enrolled from year 2002 to 2012. Among them, fifteen patients had diabetic history for over ten years, eleven patients were having repetitive hemodialysis. Their ages were 40–81(mean 67), average hospitalization period were 81.6 days. Results: As results, fifty-seven strains were isolated. Among them, 62% strains were Gram-positive cocci, 33% were Gramnegative rods, 5% were Gram-positive rods. Two or more strains were detected in fifteen patients. Indigenous bacteria of skin such as MSSA were most commonly cultured (n = 10). MRSA was found only in one patient. Sixty-seven percent of Peptostreptococci (n = 7), and seventy-five percent of E.coli (n = 4) were resistant to new quinolones. All Enterococci (n = 6) were susceptible to penicillin. Seventy percent of operated patients had no complications and discharged normally. Others had re-operation, including two cases dead due to heart disease. Most commonly used antimicrobial agents for prophylaxis were cefazolin (n = 8). However, sixty percent of all operated cases had resistant bacterial strain against cefazolin. Conclusion: We conclude that in order to avoid inappropriate anti-microbial therapy, it is important to confirm antimicrobial susceptibility with bacterial culture before operation. Use of cefazolin as the first choice prophylaxis antimicrobials should be re-considered for diabetic gangrene amputation.