Identification ofCandida albicans, otherCandidaspecies andTorulopsis glabrataby means of immunofluorescence

Diagnosis of systemic mycoses by specific immunohistochemical tests

Immunohistochemistry has proved to be a powerful tool for the accurate diagnosis of a number of important mycoses in humans and animals, such as aspergillosis, candidosis, cryptococcosis, blastomycosis, coccidioidomycosis, histoplasmosis capsulati and duboisii, paracoccidioidomycosis, fusariosis, pseudallescheriosis (scedosporiosis), sporotrichosis, trichosporonosis, penicilliosis, and zygomycosis (mucormycosis). These techniques are also applicable to pneumocystosis and to non-mycotic infections caused by algae such as protothecosis. Apart from the specificity of immunohistochemistry, the application of fluorochromes is highly effective for the localization of typical or atypical fungal elements in lesions with only few organisms present. Occasionally, a dual aetiology of fungal infections may be suspected on the basis of morphological study, and dual staining techniques have the capacity for resolving this question by simultaneous and differential staining of two fungal species present in a tissue specimen.

Enzyme immunohistochemistry with mono- and polyclonal antibodies in the pathological diagnosis of systemic bovine mycoses

To improve the immunohistopathological diagnosis of systemic bovine mycoses, we have evaluated the utility of antifungal polyclonal and monoclonal antibodies, and peroxidase and alkaline phosphatase staining techniques. A rabbit polyclonal antibody to mannan from Candida albicans was specific for candidosis. The diagnosis of aspergillosis was accomplished using a rat monoclonal antibody to the galactofuran side chains of Aspergillus galactomannan. A murine monoclonal antibody reacting with weakly Con-A binding 41 and 46 kDa somatic antigens from Absidia corymbifera was used for immunostaining of zygomycetic hyphae. Peroxidase antiperoxidase (PAP) and alkaline phosphatase antialkaline phosphatase (APAAP) complexes were visualized using aminoethylcarbazole and fast red substrates. A green staining of PAP reactions with dioctyl sulfosuccinate sodium and 3,3',5,5'-tetramethylbenzidine (DONS/TMB) was effective for the demonstration of fungi in dual and triple infections. Tissue sections of experimentally infected mice were used to determine the sensitivity and specificity of the antibodies. Tissues obtained from 161 bovine mycotic lesions previously studied by indirect immunofluorescence staining were further evaluated using the three antibodies. In all of 45 lesions solely affected by aspergillosis and in three solely affected by candidosis the diagnoses were confirmed by the new evaluation. In 85 of 96 cases of single infections with zygomycetes the diagnosis was confirmed, while none of the antibodies reacted with fungal elements in the remaining 11 lesions. Aspergillus hyphae were detected in all three lesions with dual aspergillosis and zygomycosis, whereas zygomycetic material was confirmed in only two of these cases. A mixed infection of candidosis and zygomycosis in a lymph node was confirmed too. In 13 cases in which a diagnosis had not hitherto been obtained, aspergillosis and zygomycosis were recorded each in three cases.

Immunohistologic diagnosis of systemic mycoses: an update

Fluorescent antibody, immunoperoxidase and gold-silver staining methods for the rapid and accurate diagnosis of systemic mycotic infections are currently performed in a few specialized laboratories. These methods have proved applicable to formalin-fixed, paraffin-embedded tissues, and are reliable for identifying therein antigens of infectious dimorphic, monomorphic filamentous, and yeast-like fungal pathogens, i.e., Aspergillus spp., Blastomyces dermatitidis, Candida spp., Coccidioides immitis, Cryptococcus neoformans, Fusarium spp., Histoplasma capsulatum, Paracoccidioides brasiliensis, Pseudallescheria boydii, and Sporothrix schenckii. Most of the available reagents are derived from multiple adsorbed polyclonal antisera. However, problems occur in the production of uniform and standardized species- or genus- specific antibodies. Monoclonal antibodies, although promising, have to date not eliminated these problems. Immunohistologic methods will become more routinely used in clinical laboratories as these problems are resolved and more sensitive and specific reagents become commercially available.

Bovine mycotic abortion--a comparative study of diagnostic methods

The agreement between three diagnostic methods (mycology, morphology, and immunofluorescence staining) was compared two by two in elucidating the aetiological diagnosis in 52 cases of bovine mycotic abortion. Agreement between the three methods was expressed by the kappa coefficient (kappa), and ranked as follows: mycology and immunofluorescence staining (kappa = 0.48); morphology and immunofluorescence staining (kappa = 0.40); mycology and morphology (kappa = 0.28). A. fumigatus was confirmed to be the main cause of bovine mycotic abortion with members of the zygomycetes (order Mucorales) being the second most important group. In two aborted placentas a Candida species was found to be the cause of mycotic placentitis.

Antigenic variability of Candida albicans

The concepts of modern biology lead us to think that all structures are liable to continual changes. Ultrastructural and biochemical methods have been able to objectify such a dynamic in Candida albicans, an opportunistic yeast. A broad analysis of antigens is a reliable way to study the antigenic variations which concern this organism. Numerous information on somatic and metabolic antigens of C. albicans is available at the moment. Paradoxically, if one accepts studies dealing with dimorphism, very few works have shown antigenic variability of this species or investigated the mechanisms involved in such a variability. The few approaches done in this way tend to prove that it may be possible to link together the expression of particular antigens and the behavior of the yeast, particularly when it acts as a pathogen.

Adherence of digested tissue sections for fungal immunofluorescence

Specific immunofluorescence (IF) staining is helpful and often decisive in diagnosis of deep mycoses by examination of host tissue sections. Brightness of fluorescence may be significantly enhanced by prior digestion of tissues with trypsin, but the treatment tends to separate sections from slides. This is avoided by replacement of albumin in the process by an inexpensive commercial product, Elmer's Glue-All. The entire IF staining procedure for fungi in tissue sections is reviewed here, with emphasis on adhesion and digestion of sections.