Causative Agents and Factors Associated With Multidrug Resistant Pathogens in Diabetic Foot Infections

Objective: In this study, it was aimed to investigate the infecting agents and their resistance rates and to determine the risk factors with regard to growth of multidrug resistant (MDR) organisms in patients with diabetic foot infections. Methods: Follow-up forms of 114 diabetic foot patients who had completed their treatments at the care unit for chronic wounds, and their infections between September 2016 and August 2017 were evaluated retrospectively. According to the antimicrobial susceptibility testing, Gram-negative organisms resistant to at least two antimicrobial category, enterococci resistant to penicillin group, or staphylococci resistant to methicillin were accepted as MDR. One MDR isolate was assumed sufficient for evaluation in case more than two organisms were isolated in the same culture. Results: Of 114 patients who were included in this study, 73 (64%) were male. Ninety one (79.8%) of the patients had stage 3 and 4 foot infections according to the PEDIS classification. Microorganisms were isolated in 85 (74.6%) cultures taken from wound sites, and 11 (12.9%) of them were dual growth. A total of 96 organisms, 35 (36.4%) Gram-positives and 61 (63.6%) Gram-negatives, were isolated. The most frequent isolates were 24 (25%) coagulase-negative staphylococci, 19 (19.8%) Pseudomonas aeruginosa and 12 (12.5%) Escherichia coli. Among all isolates, 46 (47.9%) were MDR in the initial wound site cultures. MDR rates of the most frequently-isolated bacteria were 66.7% for coagulase-negative staphylococci, 89.5% for P. aeruginosa and 41.7% for E. coli. Growth of an MDR pathogen was significantly associated with peripheral arterial disease (p <= 0.001), hypertension (p <= 0.001), polymicrobial growth (p=0.023) and history of hospitalization (p=0.026). However, its association with osteomyelitis was not found to reach a significant level statistically (p=0.052). Conclusions: Out of every four patients, three yielded an organism in their initial deep tissue cultures. Of the most frequently-isolated infections, MDR rates were among the highest rates in similar studies. Resistance to antibiotics is a major problem that threatens human life throughout the world, and as we have seen in our study, this threat is also apparent for diabetic foot infections.