Efficacy of a rhamnolipid biosurfactant to inhibit Trichophyton rubrum in vitro and in a mice model of dermatophytosis

Abstract

Dermatophytic infections caused by Trichophyton rubrum are the most prevalent superficial mycoses worldwide. The present study was aimed at evaluating the anti‐dermatophytic effect of a rhamnolipid biosurfactant (RL) produced by Pseudomonas aeruginosa SS14 (GenBank Accession no. KC866140) against T. rubrum in experimentally induced dermatophytosis in mice models. The purified RL could effectively suppress spore germination and hyphal proliferation of T. rubrum at 500 μg/mL. Ultramicroscopic observations involving SEM and AFM studies revealed severely altered hyphal morphology in the RL‐treated mycelia. The membrane disruptive effect of RL was measured by the uptake of propidium iodide (PI) as visualized by CLSM. The absorbance of the RL‐treated cell suspension at 260 nm showed concentration‐dependant exudation of nucleic acid due to loss of cell membrane integrity. On evaluation of the therapeutic efficacy of RL on experimentally induced cutaneous dermatophytosis in mice models, we observed that the RL, when applied topically at a concentration of 500 μg/mL, was effective in completely curing dermatophytosis at the end of 21‐day treatment period. The results were statistically similar to those obtained using the standard drug terbinafine as control. Apart from macroscopic observation, the results were confirmed by culture of skin scrapings and histopathological examination. The results are suggestive of the effectiveness of RL in control of dermatophytosis caused by T. rubrum.

Analysis on the pathogenic fungi in patients with superficial mycosis in the Northeastern China during 10 years

“…The results were different from the previous research results in Jilin (17). However, Trichophyton rubrum is still the first pathogen species, and most studies in China and worldwide also show that Trichophyton rubrum is the primary pathogen of superficial mycosis (18)(19)(20)(21). The difference is that in northern China, Trichophyton mentagrophytes and Microsporum canis are often the second and third pathogenic fungi, while in southern China, Candida is often the second pathogenic fungi (22).…”

Rhamnolipid exhibits anti-biofilm activity against the dermatophytic fungi Trichophyton rubrum and Trichophyton mentagrophytes

“…However, anti-biofilm activities of RLs against filamentous fungal species are rarely reported. Based on our previous findings demonstrating the inhibitory effect of RL-SS14 against the planktonic cells of T. rubrum [ 25 ] and the fact that dermatophytic infections are frequently related to biofilm formation, the current study investigates the effect of RL-SS14 against the sessile forms of T. rubrum and T. mentagrophytes .…”

“…Despite RLs being potent antimicrobial agents, reports documenting their use against fungal biofilms are sketchy, with the majority of the studies being limited to Candida biofilms [ 24 ]. We have earlier investigated the antifungal activities of RL against the planktonic forms of T. rubrum and obtained promising results [ 25 ]. Hence, to further the information on the antifungal properties of RL, this study reports the effects on the biofilms formed by T. rubrum and T. mentagrophytes .…”

Contributions of Glycolipid Biosurfactants and Glycolipid-Modified Materials to Antimicrobial Strategy: A Review

“…On the other hand, rhamnolipids are able to combat those harmful fungi derived from animals or humans. For instance, Sen et al elucidated that purified rhamnolipid could effectively suppress spore germination and hyphal proliferation of Trichophyton rubrum in mice models at a concentration of 500 µg/mL, which can be a promising candidate to cure dermatophytic infections, known as the most prevalent superficial mycoses worldwide [36]. Meanwhile, the biofilm of fungi has always been detrimental to eliminate microbial contamination because of its high resistance and low living demands, yet rhamnolipids have outstanding performance in controlling fungi biofilm.…”