Phaeohyphomycosis by Alternaria alternarnata : A Case study: In-vitro Sensitivity and Exoantigen Studies

Phaeohyphomycosis by Alternaria alternarnata : A Case study: In-vitro Sensitivity and Exoantigen Studies

Alternaria alternata is the most frequently encountered species of Alternaria causing opportunistic mycoses. Two cases of phaeohyphomycosis are being reported in which Alternaria alternata was isolated from peripheral blood samples of 35 year and 21 year old male TB and post operative patients respectively. The direct microscopic examination of the blood samples revealed dark dematiaceous, septate mycelium. A. alternata was repeatedly isolated from the clinical samples of both the patients. Ketoconazole with the MIC of 10 mgml-1 was found to be the best effective drug against both the Alternaria alternata strains tested in vitro. In the present study we tried to evaluate the role of exoantigens in the serological diagnosis of such infections. The exoantigen of A. alternate on SDSPAGE analysis exhibited two bands of 15Kda and 67Kda. The antisera raised in rabbit against. A alternata exoantigen showed humoral response after one week of immunization of ODD method. No cross reactivity was seen with antisera raised in rabbit against Curvularia verreculosa and Cladosporum cladosporiodides. Formation of specific precipitin bands and no cross reactivity suggests the usefulness of Alternaria alternata exoantigen as diagnostic tool. The antisera analysis by SDS-PAGE revealed several additional bands particularly higher than 67 Kda molecular weight as compared to the normal (unchallenged) sera from the same rabbit. Whether any of these bands could be treated as specific marker for diagnosis needs further investigations..