The Impact of Multidrug-Resistant Organisms on Outcomes in Patients with Diabetic Foot Infections

Background. Multidrug-resistant organisms (MDROs) are important diabetic foot infection (DFI) pathogens. This study evaluated the impact of DFIs associated with MDRO pathogens (DFI-MDRO) on clinical outcomes. Methods. Adults admitted to Detroit Medical Center from January 2012 to December 2015 with culture-positive DFI were included. Associations between outcomes and DFI-MDRO (evaluated as a single group that included methicillin-resistant Staphylococcus aureus [MRSA], vancomycin-resistant enterococci, Enterobacteriaceae resistant to third-generation cephalosporin [3GCR-EC], Acinetobacter baumannii, and Pseudomonas aeruginosa) were analyzed. Outcomes included above- and below-knee lower extremity amputation (LEA), readmissions, and mortality within a year after DFI. A propensity score predicting the likelihood of having DFI-MDRO was computed by comparing patients with DFI-MDRO with patients with DFI with non-MDRO pathogens (DFI-non-MDRO). Using conditional logistic regression, DFI-MDRO was analyzed as an independent variable after patients in the MDRO and non-MDRO groups were matched by propensity score. Results. Six hundred forty-eight patients were included, with a mean age ± SD of 58.4 ± 13.7. Most patients in the cohort presented with chronic infection (75%). DFI-MDRO occurred in greater than one-half of the cohort (n = 364, 56%), and MRSA was the most common MDRO (n = 224, 62% of the DFI-MDRO group). In propensity-matched analyses, DFI-MDRO was not associated with 1-year LEA or readmissions, but was associated with recurrent DFI episodes (odds ratio, 2.1; 95% confidence interval, 1.38–3.21). Conclusions. DFI-MDRO was associated with a 2-fold increased risk of recurrent DFI compared with patients with DFI-non-MDRO

Epidemiology of Diabetic Foot Infection in the Metro-Detroit Area with a Focus on Independent Predictors for Pathogens Resistant to Recommended Empiric Antimicrobial Therapy

Background. The polymicrobial nature of diabetic foot infection (DFI) and the emergence of antimicrobial resistance have complicated DFI treatment. Current treatment guidelines for deep DFI recommend coverage of methicillin-resistant Staphylococcus aureus (MRSA) and susceptible Enterobacteriaceae. This study aimed to describe the epidemiology of DFI and to identify predictors for DFI associated with multidrug-resistant organisms (MDROs) and pathogens resistant to recommended treatment (PRRT). Methods. Adult patients admitted to Detroit Medical Center from January 2012 to December 2015 with DFI and positive cultures were included. Demographics, comorbidities, microbiological history, sepsis severity, and antimicrobial use within 3 months before DFI were obtained retrospectively. DFI-PRRT was defined as a DFI associated with a pathogen resistant to both vancomycin and ceftriaxone. DFI-MDRO pathogens included MRSA in addition to PRRT. Results. Six-hundred forty-eight unique patients were included, with a mean age of 58.4 ± 13.7 years. DFI-MDRO accounted for 364 (56%) of the cohort, and 194 (30%) patients had DFI-PRRT. Independent predictors for DFI-PRRT included history of PRRT in a diabetic foot ulcer, antimicrobial exposure in the prior 90 days, peripheral vascular disease, and chronic kidney disease. Long-term care facility residence was independently associated with DFI due to ceftriaxone-resistant Enterobacteriaceae, and recent hospitalization was an independent predictor of DFI due to vancomycin-resistant Enterococcus. Conclusions. An unexpectedly high prevalence of DFI-PRRT pathogens was identified. History of the same pathogen in a prior diabetic foot ulcer and recent antimicrobial exposure were independent predictors of DFI-PRRT and should be considered when selecting empiric DFI therapy