Journal of medical and veterinary mycology : bi-monthly publication of the International Society for Human and Animal Mycology最新文献

Critical steps implicated in the polymorphism of Wangiella dermatitidis were found to be sensitive to calcium ion availability. When grown in a defined, synthetic medium under various pH and temperature conditions, two thresholds of calcium ion concentrations were identified: a lower concentration favouring non-polarized growth leading to multicellular form development and a higher concentration promoting polarized growth characterized by yeast budding or pseudo/true hyphal growth. The phenotypic transition of yeasts to multicellular forms or to hyphae was induced at both 25 and 37 degrees C in the wild-type strain by the addition of calcium to the synthetic medium adjusted to pH 2.5, which was otherwise not conducive to the production of either growth form. However, the calcium additions did not allow maintenance of polarized growth of yeasts or hyphae in a temperature-sensitive, cell-division-cycle mutant (wdcdc2) derived from the same strain and grown at 37 degrees C in the same medium adjusted to either pH 2.5 or 6.5. Instead these conditions allowed only the nonpolarized, multicellular form development associated with this conditional mutant cultured in rich media at the 37 degree C restrictive temperature for yeast bud formation. Results from experiments using the calcium chelator EGTA added to the synthetic medium supported these conclusions at neutral pH with both the wild type and the wdcdc2 mutant cultured at 37 degrees C. The results suggested that during infection different concentrations of calcium may be encountered by W. dermatitidis in different tissues, which might directly regulate its growth and polymorphism and indirectly its virulence depending on host conditions.

We report the identification of Blastomyces dermatitidis by microscopic examination of a direct faecal smear from a dog with pulmonary blastomycosis. A simultaneously obtained faecal culture grew Blastomyces dermatitidis. The fungus was also cultured from a transtracheal sample from this same dog. This report suggests that yeast-phase cells of B. dermatitidis may be recovered in the stool of dogs with pulmonary blastomycosis following transit through the gastrointestinal tract of swallowed infected sputum. Implications regarding the ecology of Blastomyces dermatitidis are discussed.

Around Port Moresby, Papua New Guinea (PNG), the annual incidence of cryptococcal meningitis is estimated to be up to 42.8 per million population; Cryptococcus neoformans var. gattii is the predominant causative agent. In Australia and California, environmental isolations have established an ecological association of C. neoformans var. gattii with Eucalyptus camaldulensis, E. tereticornis, and more recently E. rudis and E. gomphcephala. In PNG few E. camaldulensis survive experimental planting, E. tereticornis is endemic and there are no records of planting of the non-endemic E. rudis and E. gomphcephela. Despite extensive sampling of eucalypt-associated and other sources, we were unable to identify the ecological niche of C. neoformans var. gattii and neoformans in this region.

The specificity of random primer R143 for Aspergillus fumigatus DNA was determined in order to test its usefulness in establishing the presence of A. fumigatus DNA in fungal cultures. When PCR reaction products of these cultures were compared with those of 21 other bacterial and fungal DNA samples, R143 proved to produce a 1346 bp band with only A. fumigatus. This band has been sequenced completely and the EcoRI restriction site was used for subsequent confirmation of PCR products. The specificity for A. fumigatus DNA was also confirmed by Southern blotting. Comparison of morphological typing of Aspergillus species in cultures with PCR using R143 on DNA isolated from these cultures showed concordance in 22 of 24 cases. In two cases there was discordance: both times PCR results showed correctly the presence of A. fumigatus, initially not detected by culture. R143 is an A. fumigatus specific random primer, with potential for use in detection of A. fumigatus DNA in clinical specimens.

Metarhizium anisopliae var. anisopliae (Metschnikov) Sorokin 1883 to our knowledge has never been reported as an agent of human or animal mycosis. This fungus has great importance as an agent of biological control of different pests and mosquito larvae in Colombia. It has been isolated as the aetiological agent of keratomycosis for the first time from the eye of a Colombian male.

The susceptibility of 64 Malassezia furfur isolates to Melaleuca alternifolia oil was determined. The minimum inhibitory concentration for 90% of isolates was 0.25% by agar dilution and 0.12% by broth dilution. These data indicate that tea tree oil may be useful in the treatment of skin conditions involving M. furfur.