Diabetic Foot Infection: Microbiologic Analysis Based on Deep Tissue Biopsy

Seo, Yu Bin; Noh, Ji Yun; Huh, Joong Yeon; Lee, Jacob; Song, Joon Young; Han, Seung Kyu; Kim, Woo Joo; Cheong, Hee Jin

Abstract

BACKGROUND: The annual prevalence of foot ulcer in Korea is 99.5 per 100,000 people with diabetes and 49.8 cases among them go through amputation. Moreover, amputation due to uncontrolled infection accounts for 50% of all non-traumatic limb amputations. Therefore, reliable microbiological documentation is important.
MATERIALS AND METHODS
We enrolled 74 patients with diabetic foot infection, who referred to Korea University Hospital from September 2006 to March 2007. Deep tissue biopsies were taken from the base of ulcer after surgical debridement and cleansing at admission. We analyzed the microbiological differences according to the sex, age, type and duration of diabetes, glycemic control, presence of neuropathy or angiopathy, diabetic nephropathy, osteomyelitis, transcutaneous oxygen tension and prior antibiotic use.
RESULTS
Gram-positive aerobic bacteria were the most common organisms isolated (76.4%), followed by Gram-negative aerobic bacteria (33.3%) and fungus (2.0%). Of the Gram-positive aerobes, methicillin-resistant Staphylococcus aureus (MRSA) was found most frequently (29.4%). The clinical and laboratory findings showed no significant clinical differences between gram-positive and gram-negative infections. Moreover, there was no difference in clinical findings between methicillin-susceptible and methicillin-resistant S. aureus infections. Mixed infection was not common (average, 1.2 organisms with each diabetic foot infection). Of note, mixed infection was more frequently found in patients with prior antibiotic use.
CONCLUSION
MRSA was the most common pathogen in diabetic foot infection among patients referred to tertiary hospital. There was no significant difference of clinical and laboratory findings with regard to gram stain results and methicillin resistance in S. aureus. Mixed infection was not common, but broad spectrum antibiotics are recommended for severe diabetic foot infection with prior antibiotic exposure.