Resumen

TORRES, Joel; ROMERO, Hilda; SANTIAGO, Axel  y  APITZ CASTRO, Rafael. In vitro susceptibility of Histoplasma capsulatum to ajoene using disk and holes diffusion methods. Rev. Soc. Ven. Microbiol. [online]. 2006, vol.26, n.1, pp.42-47. ISSN 1315-2556.

The sensibility of Histoplasma capsulatum to ajoene was evaluated through disk (DDM) and holes (HDM) diffusion methods, using Sabouraud dextrose (SDA) and modified Mueller-Hinton (MHM) agars. The fungal inoculum, obtained from the exponential growth phase,  was adjusted to 0.5 Mc-Farland and seeded (0,2 ml) on the plates. For DDM, the protocol M44A-NCCLS was followed, with some modifications; for HDM, 4 mm-holes were punched and proceeded as for DDM. Ajoene was used at concentrations from 3.75 to 120 µg. The plates were kept at room temperature and the inhibition was recorded at days seven and 16. All the assays were run by duplicate. On day seven, the DDM using SDA revealed inhibition zones from 15 µg of ajoene and when using MHM, the inhibition was observed from 30µg. With HDM, ajoene inhibited fungal growth from 7.5 µg when using SDA and with MHM, this effect was noticed from 30 µg. Day 16 showed a considerably decrease of the inhibition zones, by both methods, with the two media, which demonstrates a fungistatic effect of ajoene on this fungus. Taking in account these results, it could be considered that H.capsulatum (mycelial phase) is susceptible to 15 µg of ajoene by both methods, with SDA and with MHM, to 30 (DDM) and 60 µg (HDM). Both methodologies demonstrated validity to perform sensibility tests with H.capsulatum, using both culture media.These promising results justify further research to confirm the findings of the present work.

Palabras clave : Histoplasma capsulatum; Histoplasmosis; Antifungal drugs; Ajoene; Agar diffusion methods.