Wound Chronicity, Inpatient Care, and Chronic Kidney Disease Predispose to MRSA Infection in Diabetic Foot Ulcers

Abstract

OBJECTIVE To determine the microbiological profile of diabetes-related foot infections (DRFIs) and the impact of wound duration, inpatient treatment, and chronic kidney disease (CKD). RESEARCH DESIGN AND METHODS Postdebridement microbiological samples were collected from individuals presenting with DRFIs from 1 January 2005 to 31 December 2007. RESULTS A total of 653 specimens were collected from 379 individuals with 36% identifying only one isolate. Of the total isolates, 77% were gram-positive bacteria (staphylococci 43%, streptococci 13%). Methicillin-resistant Staphylococcus aureus (MRSA) was isolated from 23%; risk factors for MRSA included prolonged wound duration (odds ratio 2.31), inpatient management (2.19), and CKD (OR 1.49). Gram-negative infections were more prevalent with inpatient management (P = 0.002) and prolonged wound duration (P < 0.001). Pseudomonal isolates were more common in chronic wounds (P < 0.001). CONCLUSIONS DRFIs are predominantly due to gram-positive aerobes but are usually polymicrobial and increase in complexity with inpatient care and ulcer duration. In the presence of prolonged duration, inpatient management, or CKD, empiric MRSA antibiotic cover should be considered.