Clinical and Microbiological Profile of Diabetic Foot Ulcers Infected With Staphylococcus aureus in a Regional General Hospital in Bahia, Brazil

Abstract

It is necessary to know the resistance profile of Staphylococcus aureus to better control diabetic foot ulcer infections, to establish rational antibiotic therapy, and to avoid the development of resistant strains. This cross-sectional study evaluated the clinical parameters, virulence, and antimicrobial resistance profiles of S aureus in patients with diabetic foot disease admitted to a public hospital. S aureus strains were identified in patients with diabetes with amputation indication. Infected tissue samples were collected, microbes were isolated and identified. The microbial resistance profile was determined. Samples were also analyzed for biofilm formation and other virulence markers. The 34 individuals examined were mostly men, black, aged 60 years on average, and generally had a low income and education level. Most individuals had type 2 diabetes, and the mean time since diagnosis was 13.9 years. On an SF-36 (the Medical Outcomes Study 36-item short-form health survey) quality-of-life questionnaire, 75% of individuals obtained a score equal to 0 for physical impairment. S aureus specimens from 17 patients were isolated, corresponding to 50% of samples. Five isolates were classified as methicillin-resistant S aureus (MRSA). Molecular typing revealed that 20% of MRSA strains were SCC mec type V and 80% were type I. All isolates were sensitive to doxycycline; 61.5% were resistant to erythromycin, 38.5% to cefoxitin, 30.7% to clindamycin and ciprofloxacin, 23% to meropenem, 15.3% to gentamicin, 38.5% to oxacillin, and 7.7% (one strain) to vancomycin. Regarding biofilm production, 53% of samples were able to produce biofilms, and 84.6% had icaA and/or icaD genes . Additionally, the following enterotoxin genes were identified in the isolates: seb, sec, seg, and sei (5.9%, 5.9%, 11.8%, and 23.9%, respectively) and agr types 1 (5.9%) and 2 (11.8%). Genotypic evaluation made it possible to understand the pathogenicity of S aureus strains isolated from the diabetic foot; laboratory tests can assist in the monitoring of patients with systemic involvement.