Risk factors and healing impact of multidrug-resistant bacteria in diabetic foot ulcers

To determine the risk factors for acquiring multidrug-resistant organisms (MDRO) and their impact on outcome in infected diabetic foot ulcers.

Patients hospitalized in our diabetic foot unit for an episode of infected foot ulcer were prospectively included. Diagnosis of infection was based on clinical findings using the International Working Group on the Diabetic Foot-Infectious Diseases Society of America (IWGDF-ISDA) system, and wound specimens were obtained for bacterial cultures. Each patient was followed-up for 1 year. Univariate analysis was performed to compare infected ulcers according to the presence or absence of MDRO; logistic regression was used to identify explanatory variables for MDRO presence. Factors related to healing time were evaluated by univariate and multivariate survival analyses.

MDRO were isolated in 45 (23.9%) of the 188 patients studied. Deep and recurrent ulcer, previous hospitalization, HbA(1c) level, nephropathy and retinopathy were significantly associated with MDRO-infected ulceration. By multivariate analysis, previous hospitalization (OR=99.6, 95% CI=[19.9-499.0]) and proliferative retinopathy (OR=7.4, 95% CI=[1.6-33.7]) significantly increased the risk of MDRO infection. Superficial ulcers were associated with a significant decrease in healing time, whereas neuroischaemic ulcer, proliferative retinopathy and high HbA(1c) level were associated with an increased healing time. In the multivariate analysis, presence of MDRO had no significant influence on healing time.

MDRO are pathogens frequently isolated from diabetic foot infection in our foot clinic. Nevertheless, their presence appears to have no significant impact on healing time if early aggressive treatment, as in the present study, is given, including empirical broad-spectrum antibiotic treatment, later adjusted according to microbiological findings.