Effect of Potassium Permanganate on Staphylococcal Isolates Derived from the Skin of Patients with Atopic Dermatitis

Abstract

In atopic dermatitis (AD), Staphylococcus aureus frequently colonizes lesions, leading to superinfections that can then lead to exacerbations. The presence of biofilm-producing isolates has been associated with worsening of the disease. Potassium permanganate is used as a topical treatment of infected eczema, blistering conditions, and wounds. Little is known of its effects against microbes in AD skin. The aim of this study was to explore antibacterial and antibiofilm properties of potassium permanganate against staphylococcal isolates derived from AD skin. Viable count and radial diffusion assays were used to investigate antibacterial effects of potassium permanganate against planktonic staphylococcal isolates. The antibiofilm effects were assessed using biofilm assays and scanning electron microscopy. The Staphylococcus aureus isolates were completely killed when exposed to 0.05% of potassium permanganate. In concentrations of 0.01%, potassium permanganate inhibited bacterial biofilm formation. Eradication of established staphylococcal biofilm was observed in concentrations of 1%. Electron microscopy revealed dense formations of coccoidal structures in growth control and looser formations of deformed bacteria when exposed to potassium permanganate. This suggests antibacterial and antibiofilm effects of potassium permanganate against staphylococcal isolates derived from AD skin, when tested in vitro, and a potential role in the treatment of superinfected AD skin.

Fig. 1

Antibacterial effects on planktonic S. aureus ^and S. epidermidis isolates. Clinical S. aureus and S. epidermidis isolates from patients with AD and 2 ATCC strains who have been exposed to potassium permanganate in a concentration range between 0.01% and 0.5% for 10 min, followed by counting of viable colonies. Values indicated with an asterisk are significant (**p ≤ 0.002, ***p ≤ 0.0005) different from growth controls as analysed by Wilcoxon signed-rank test, GraphPad Prism8. Total reduction in colony-forming units (cfu), (no detectable growth) is seen for bacteria exposed to potassium permanganate at concentrations of 0.1% and 0.5%.

Fig. 2

Inhibition of staphylococcal growth. (a) Antibacterial effects of different concentrations of potassium permanganate against multiple clinical isolates of S. aureus, S. epidermidis, and reference ATCC strains. Results are presented as the mean size of inhibitory zones ± standard deviation (SD), in radial diffusion assay (RDA), of 3 independent experiments. (b) A picture of RDA agar plate with visual clear zones indicating antibacterial effect.

Fig. 3

Inhibition of biofilm formation. Production of S. aureus and S. epidermidis biofilm in the presence of potassium permanganate. After 24 h the biofilms were stained with crystal violet, washed, and dissolved in ethanol; the absorbance was read with enzyme-linked immunoassay (ELISA). Results are shown as mean absorbance (OD600) ± standard deviation (SD), of 3 independent experiments, corresponding to the quantity of biofilm produced. For the vast majority of the isolates a dose-dependent reduction in biofilm formation was seen.

Fig. 4

Scanning electron microscopy (SEM) of potassium permanganate-treated staphylococcal communities. SEM examination of the distribution of bacterial biofilm on plastic pegs after treatment with potassium permanganate in different concentrations. With a higher concentration of potassium permanganate, fewer bacteria are seen. (a) S. aureus ATCC 29213. The rounded structures of the bacteria are altered in 1% concentration. (b) S. aureus clinical isolate 3.