Effect of Azadirachta indica (neem) on the growth pattern of dermatophytes.

PURPOSE: To determine the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) for the extracts of the leaves and seeds of the plant Azadirachta indica against various dermatophytes. METHODS: Clinical isolates of dermatophytes(Trichophyton rubrum, Trichophyton mentagrophytes and Microsporum nanum) were treated with extracts of leaves and seeds of the plant Azadirachta indica (neem) for antifungal activity by in vitro tube dilution technique. RESULTS: The MIC of neem seed extracts was 31 microg/mL for all the dermatophytes tested. The neem seed extract at 15 microg/mL concentration (below MIC) was observed to be sufficient for distorting the growth pattern of the organisms tested. CONCLUSIONS: The changes in growth curve of the treated dermatophytes were found to be statistically significant with reference to the untreated fungi.

In vitro susceptibility of filamentous fungi to itraconazole.

The in vitro activity of itraconazole was investigated against 25 clinical isolates of filamentous fungi by agar dilution method. The isolated included Aspergillus sp., hyalohypomycetes, dematiaceous fungi and zygomycetes. Intraconazole was more active, inhibiting 50% (MIC 50) and 90% (MIC 90) of the Aspergillus sp., at a concentration of 0.5 and 2.5 ug ml-1 (MIC range 0.1 and 5 micrograms ml-1) Ketoconazole (MIC range 0.5-10 ug ml-1) required 1 and 5 ug ml-1 for inhibiting 50% and 90% of the isolates. For the hyalophypomycetes and dematiaceous fungi, the MIC 50s for itraconazole were 1 and 0.5 ug ml-1 and Ketoconazole required 2.5 ug ml-1 for both the groups. For the zygomycetes, the MIC range and MIC 50s for Ketoconazole were 1-100 and 10 ug ml-1 whereas the values for itraconazole were 5- > 100 and > 100 micrograms ml-1.

Disk diffusion susceptibility testing of dermatophytes with imidazoles.

In vitro susceptibility testing of 43 isolates of dermatophytes was carried out against imidazoles-ketoconazole, miconazole and econazole and griseofulvin by agar dilution and disk diffusion methods. Econazole was the most effective drug inhibiting all the isolates at a concentration of 0.1 microgram ml-1. The MIC 50s and MIC 90s for ketoconazole and miconazole were 1 and 2.5 mg ml-1 whereas the values for griseofulvin were 1 and 5 micrograms ml-1. Good correlation was seen between the MIC and sizes of zones of inhibition around the disks. Regression analysis was used to measure the degree of correlation between the MIC values and matched averaged zones of inhibition and the correlation coefficients for econazole, ketoconazole, miconazole and griseofulvin were -0.5554, -0.5886, -0.8558 and -0.8268 (p < 0.001) respectively.

Antimycotic susceptibility testing of mould-fungi with allylamines by disk diffusion.

Susceptibility testing of 17 clinical isolates of mould-fungi, which included Aspergillus spp., (8) Penicillium spp., (2) Paecilomyces spp., (1) Cladosporium spp., (1) Pyrenochaeta romeroi (1) Rhizopus spp., 2. Syncephalastrum spp., (1) and Mortierella spp., (1) were carried out against allylamines-naftifine and terbinafine-(Sandoz Forchungsinstitut) by agar dilution and disk diffusion techniques. Terbinafine was more active than naftifine inhibiting 50 and 90% of the fungi other than zygomycetes at a concentration of 0.5 and 1 microgram/ml whereas the values for naftifine were 2.5 and 10 micrograms/ml. The MIC range for zygomycetes for terbinafine and naftifine were 1-->100 and 100-->100 respectively. The MICs and the sizes of zones of inhibition around the disks correlated well and the degree of correlation was measured by regression analysis. The correlation coefficients for naftifine and terbinafine were-0.9597 and -0.9174 (P < 0.007) respectively.

Antidermatophytic activity of allylamine derivatives.

The allylamine derivatives are a new class of synthetic antifungal agents. The antidermatophytic activity of the two main compounds, naftifine and terbinafine were compared in vitro with those of ketoconazole and itraconazole by agar dilution. Eighty eight clinical isolates of dematophytes comprising of Microsporum canis (50), M. audouinii (5), Trichophyton rubrum (6) T. mentagrophytes (5), T. violaceum (12), T. simii (5), T. verrucosum (1), T. soudanense (1), T. erinacie (1) and Epidermophyton floccosum (2) were tested. Terbinafine was found to be most active, inhibiting 68 of the 88 isolates at a concentration of 0.01 ug ml-1 and all at 0.1 ug ml. (Minimum inhibitory concentration - MIC range < or = 0.0001-0.1 ug ml-1). Naftifine inhibited 84 isolates at a concentration of 0.1 ug ml-1 and all at 0.5 ug ml-1 (MIC range 0.001-0.5 ug ml-1). Itraconazole required 0.1 ug ml-1 for inhibiting 50 isolates and 0.5 ug ml-1 for 85 isolates (MIC range 0.01-1 ug ml-1) whereas ketoconazole inhibited 71 isolates at 1 ug ml-1 and 87 at 2.5 ug ml-1 (MIC range 0.01-5 ug ml-1).

Antifungal activity of allylamine derivatives.

The antifungal activity of the two allylamine derivatives, naftifine and terbinafine was investigated against 25 clinical isolates of filamentous fungi by agar dilution method. The isolates included Aspergillus sp. (10), Penicillium sp. (3), Cladosporium sp. (3), Rhizopus sp. (3), Paecilomyces sp. (2), Syncephalastrum sp. (1), Pyrenochaeta romeroi (1), Piedraia hortae (1) and Mortierella sp. (1). Terbinafine was found to be more active than naftifine, inhibiting 50 per cent (MIC 50) and 90 per cent (MIC 90) of the isolates of Aspergillus sp., at 0.1 and 0.5 microgram/ml respectively. The MIC 50s for the other isolates of hyalohyphomycetes, dematiaceous fungi and zygomycetes were 1, 5 and 100 micrograms/ml respectively. Naftifine inhibited 50 and 90 per cent of the Aspergillus sp., at 1 and 5 micrograms/ml, respectively. The MIC 50s for the other hyalohyphomycetes, dematiaceous fungi and zygomycetes were 5, 10 and 100 micrograms/ml respectively.