<i>In Vitro</i> Susceptibility of Dermatophytes to Anti-Fungal Drugs and Aqueous <i>Acacia nilotica</i> Leaf Extract in Lagos, Nigeria

Abstract

Dermatophytes were earlier reported to respond well to anti-fungal agents; however, an upsurge in resistance with the high cost of these agents increased the use of medicinal plants for treatment. This study investigated the sensitivity pattern of dermatophytes to oral anti-fungal drugs and aqueous leaf extract of the plant, Acacia nilotica . The extract was tested against seven strains of dermatophytes Arthroderma otae , Trichophyton interdigitale , Trichophyton mentagrophyte , Microsporum ferrugineum , Arthroderma vespertilii , Arthroderma quadrifidum , and Arthroderma multifidum , previously isolated from diabetic patients. The minimum inhibitory and fungicidal concentrations of the plant extracts and the standard antifungal agents were evaluated using modifications of the broth macro dilution method of the National Committee for Clinical Laboratory Standards M38-A2 protocol. There was a significant difference in the Minimum Inhibitory concentrations (MIC) of the dermatophytes to the three antifungal drugs tested (p < 0.001). The dermatophytes were mostly susceptible to itraconazole followed by Nystatin. All the dermatophytes tested were resistant to griseofulvin. Acacia nilotica had an inhibitory effect on all the dermatophytes tested, and showed anti-fungal activity in a dose-dependent relationship between 0.625 - 1.25 mg/ml. Though the inhibitions of the dermatophytes were significantly higher with the standard anti-fungal drugs as compared to the plant extract (p < 0.001); however, the dermatophyte, Arthroderma quadrifidum , which was resistant to all the anti-fungal drugs, had the highest inhibition with A. nilotica . Some circulating dermatophyte strains in Nigeria are griseofulvin and/or itraconazole resistant which may influence the spread of infection and A. nilotica aqueous leaf extract showed a strong anti-dermatophytic activity.