Secreted aspartic proteinases (Saps) are important virulence factors during Candida albicans mucosal or disseminated infections. A differential expression of individual SAP genes has been shown previously in a model of oral candidosis based on reconstituted human epithelium (RHE), and in the oral cavity of patients. In this study, the ultrastructural localization of distinct groups of Sap isoenzymes expressed during RHE infection was shown by immunoelectron microscopy using specific polyclonal antibodies directed against the gene products of SAP1‐3 and SAP4‐6. Large amounts of Sap1‐3 antigen were found within C. albicans yeast and hyphal cell walls, often predominantly in close contact with epithelial cells, whereas lower quantities of Sap4‐6 were detected in hyphal cells. To elucidate the relevance of the expressed Saps during oral infections, we examined the effect of the aspartic proteinase inhibitor, pepstatin A, during infection of the RHE. The extent of lesions caused by the strain SC5314 was found to be strongly reduced by the inhibitor, indicating that proteinase activity contributes to tissue damage in this model. To clarify which of the SAP genes are important for tissue necrosis, the histology of RHE infection with Δsap1, Δsap2, Δsap3, Δsap4‐6 and three Δsap1/3 double mutants were examined. Although tissue damage was not blocked completely with these mutants, an attenuated phenotype was observed for each of the single sap null mutants, and was more strongly attenuated in the Δsap1/3 double null mutants. In contrast, the lesions caused by the Δsap4‐6 triple mutant were at least as severe as those caused by SC5314. During infection with the mutants, we observed that the SAP gene expression pattern of the Δsap1 and the Δsap1/3 mutants was altered in comparison with the wild‐type strain. Expression of SAP5 was observed only during infection with the Δsap1/3 mutant, whereas upregulation of SAP2 and SAP8 transcripts was observed in the Δsap1 and the Δsap1/3 mutants. These results suggest that Sap1‐3, but not Sap4‐6, contribute to tissue damage in this model. Furthermore, C. albicans may compensate for the deletion of certain SAP genes by upregulation of alternative SAP genes.

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Fourier transform infrared spectroscopy is an established method in the routine diagnosis of various micro-organisms, including bacteria and yeasts, on a species level. Its possible value in the diagnostics of dermatophytes was analysed using three clinical isolates each of the three most frequently found species, namely Trichophyton rubrum, Trichophyton mentagrophytes and Microsporum canis. The results encourage further work to establish a library which would allow the use of this method in the clinical setting. This might help to make repeated subcultures, which are money- and time-consuming, redundant.

A 33-year-old man presented with very itchy red papules on the back of his hands and forearms. These papules appeared about 90 min after he had cleaned his aquarium in which he kept native fish and watersnails. He had obtained the watersnails some weeks before from a nearby pond. Examination of water from the aquarium revealed cercariae. The clinical diagnosis of cercarial dermatitis was corroborated. Cercarial dermatitis has repeatedly been seen in swimmers but not in aquarists keeping fish in a home aquarium.

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