The antimicrobial susceptibility patterns of diabetic foot ulcers in the South African public healthcare sector

Abstract

Background. Diabetic foot syndrome is defined as the presence of a diabetic foot ulcer (DFU) associated with neuropathy, peripheral artery disease and infection. While the use of antimicrobials in the treatment of DFU infection remains a mainstay, the choice of antimicrobial remains problematic owing to the presence of multidrug-resistant polymicrobial infections. In the South African public healthcare sector, the treatment of DFUs is based on the Standard Treatment Guidelines (STGs) and the Essential Drug List. These guidelines are developed using evidence-based medicine and are based on global susceptibility patterns rather than local susceptibility data, and may not provide the most appropriate treatment options. Objectives. To determine the antimicrobial susceptibility patterns of DFUs isolated from patients visiting selected Gauteng provincial public hospitals in order to determine a clinically effective treatment protocol for the management of these infections. Methods. Sample swabs were taken from 51 DFUs using the Levine method. Each sample swab was spread onto blood agar plates, and thereafter individual pathogens were isolated. The antimicrobial susceptibility patterns of all isolated pathogens were determined using zone of inhibition measurements. Pathogens were grouped according to macromorphological characteristics as well as susceptibility patterns, and a representative isolate from each group was then identified. Results. A total of 51 DFU ulcer swabs from 45 patients were included in the study. From the sample swabs, a total of 445 pathogens were isolated. The most effective antimicrobial was found to be gentamicin, followed by ciprofloxacin. Amoxicillin/clavulanic acid, the first-line treatment according to the STGs, was found to be ineffective for many of the isolated pathogens. The most commonly isolated pathogens were Proteus mirabilis, Enterococcus faecalis and Pseudomonas aeruginosa. Conclusion. These findings demonstrate the urgent need to reassess the STGs and base treatment plans on local epidemiological data. This study provides valuable data on common causative pathogens in DFU infections, as well as the resistance patterns of these pathogens, forming a baseline on which to base future DFU treatment plans.

Keywords

• antimicrobial
• foot ulcer
• diabetic
• antimicrobial resistance
• susceptibility testing