In Vitro Evaluation of Novel Bacillus-Derived Lipopeptide on Clinically Prevalent Trichophyton Spp. in Dermatophytosis

Trichophyton spp. are the leading cause of dermatophytosis globally, and in India. Antifungal li¬popeptides have emerged as potential candidates for developing alternative antifungal therapies. In our previous studies, the novel lipopeptide variant AF4, purified by reversed-phase HPLC from the wild-type Bacillus subtilis, demonstrated broad-spectrum antifungal activities against fungal clinical isolates. Here we have tested AF4 against Trichophyton spp. isolated from human samples to determine the antifungal susceptibility of T. rubrum, T. mentagrophytes complex and T. tonsurans. Twenty Trichophyton spp. isolates exhibited minimum inhibitory concentrations (MICs) in the range of 2-16 mg/L (100 % inhibition). The MICs of AF4 against six Trichophtyon spp. were equivalent to or less than that of MICs of terbinafine. AF4 has also exhibited potent activity against isolates of T. mentagrophytes complex and T. rubrum that carry mutations in the squalene epoxidase gene, which confers terbinafine resistance. In conclusion, we present a novel antifungal lipopeptide capable of significantly inhibiting the growth of Trichophyton spp. that is commonly found in clinical presentations of dermatophytosis.