1 ISOLATION AND SUSCEPTIBILITY OF DERMATOPHYTIC FUNGI SPORES TO ANTIFUNGAL AGENTS IN ZARIA, NIGERIA
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Date
2008-01-09
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Ahmadu Bello University Zaria
Abstract
Tinea capitis is a highly contagious infection of the scalp and hair caused by dermatophytes. In
Nigera, as much as 30.6% of children have been reported to have these dermatophytic fungal
infection. Dermatophytic fungal isolates from pupils in three primary schools in Zaria Nigeria were
cultured, characterized and identified using standard microbiological methods. Antifungal activities
of five selected commonly used chemical agents against five most resistant dermatophytic fungal
isolates viz Trichophyton rubrum (Tr10), Trichophyton mentagrophytes (Tm07), Trichophyton
tonsurans (Tt06), Trichophyton verucosum (Tv03), and Trichophyton soudanese (Ts01), were
investigated using parameters such as Minimum Inhibitory Concentration (MIC), Minimum
Fungicidal Concentration (MFC), Fractional Inhibitory Concentration (FIC), for Antifungal Agents
Combinations and the effect of time on sporicidal activities of test chemical agents on the most
resistant dermatophytic fungal spores. A total of 81 dermatophytic fungi were isolated from 150
swabs and samples collected from the volunteered primary school pupils. The dermatophytes were
Trichophyton rubrum (12), Trichophyton mentagrophytes (18), Trichophyton verucosum (14)
Trichophyton soudanese (16), Trichophyton tonsurans (13), Trichophyton violaceum (4) and
Microsporum canis (4). Test fungal isolates with the highest incidences were Trichophyton
mentagrophytes 18(22.2%), followed by Trichophyton soudanese 16(19.8%). Microsporum canis
and Trichophyton violaceum were the least isolated, 4(4.9%) each. The M.I.C values of Flucytosine,
Terbinafine HCL, and Tioconazole range from 0.50 to 100.00μg/ml against the five selected test
fungi spores. The antifungal activity of Sodium propionate ranges from 50.0 to 250.0 μg/ml against
the five dermatophytic spores. The order of inhibitory antifungal activity was Fluconazole >
flucytosine >Terbinafine > Tioconazole > Sodium propionate. Similarly the Minimum Fungicidal
Concentration of the test antifungal agents against the five selected test fungi spores showed the
order of the antifungal activities as Fluconazole, > Terbinafine > Flucytosine > Tioconazole >
Sodium Propionate. The most resistant dermatophyte was Trichophyton rubrum. Biocidal activities
of the test compounds at 0.156μM concentration, displayed marked fungicidal activities in the
order of Terbinafine HCl >Tioconazole > sodium propionate > Fluconazole, with one log cycle
reduction time of 5.0, 7.5, 15.0, and 20.0 minutes respectively. After the first 30 minutes contact
time in the admixtures, the log cycles reduction of resistant T.rubrum spores were in the following
order; Terbinafine HCL (3.90) > Tioconazole (2.40) > Sodium Propionate (1.50) > Fluconazole
(1.20) log cycles reductions. Generally, there was rapid rate of fungicidal activity among the test
antifungal agents within the first 50 minutes. Based on the Minimum Fungicidal Concentration
(MFC) values of the test antifungal agents, six new potential combined antifungal agents were
formulated with tenfold their M.F.C. Results of the combinations of test antifungal agents against
the most resistant T. rubrum showed synergism for Terbinafine /Sodium propionate, Fluconazole/
Sodium propionate, and Tioconazole /sodium propionate. The observed results in this study proved
that the test antifungal agents singly and in combination possessed appreciable activities against the
isolated dermatophytic fungi spores in Zaria Nigeria