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

By using multilocus enzyme electrophoresis (MLEE) we have analyzed the genetic diversity encountered among chlamydospore-positive Candida albicans strains. While the type II strains of the former C. stellatoidea were genetically indistinguishable from those of C. albicans, type I strains constituted a distinct subgroup compared with C. albicans strains. Nevertheless, all these strains remained genetically very closely related compared with other species of Candida (e.g. C. tropicalis, C. krusei and C. glabrata). These results corroborate the synonymy between C. stellatoidea and C. albicans. Chlamydospore-positive C. albicans strains with atypical sugar assimilation patterns displayed a great genetic divergence from the cluster constituted by C. albicans and the strains of the former C. stellatoidea. However, these atypical strains were more closely related to C. albicans than they were to C. tropicalis, C. krusei or C. glabrata. These strains represent a genetically entity distinct from the typical C. albicans strains used in this study. The data also support the view that the atypical strains described here belong to the same genetic group as atypical C. albicans strains previously described by others.

Ten different killer sensitivity types are distinguished within Cryptococcus neoformans, namely four in var. neoformans and six in var. gattii. All strains of the var. gattii investigated were inhibited by killer toxins of C. laurentii CBS 139, whereas those of the var. neoformans were not. Killer sensitivity patterns are an easy-to-use method to differentiate between the two varieties of the clinically important yeast C. neoformans, and may be of help in epidemiological surveys.

The blood supply to the mycetoma lesion and its vasculature were studied in patients with various types of mycetoma using histological, ultrastructural, angiographic and sonographic techniques. The mycetoma lesion proved to be well vascularized. However, certain vascular abnormalities were demonstrated. In histological sections, the small arteries and arterioles showed medial muscular hypertrophy in 83%, intimal fibrosis in 33%, arteritis in 7% and endarteritis obliterans with narrowed lumen in 7% of the patients. No vascular occlusion, ischaemic changes or arteriovenous shunts were observed. These changes were confirmed ultrastructurally. Angiography of the lesion showed a brisk pathological circulation which was more evident in eumycetoma. The vascular Doppler study showed normal blood flow pattern in the affected limb. Regional intra-arterial chemotherapy for mycetoma is suggested as a possible treatment modality.

A case of prosthetic valve endocarditis caused by Cryptococcus neoformans var. neoformans is described. The infection followed closed mitral valvotomy and insertion of a valvular prosthesis. Infection was manifested 2 weeks after the operation. The diagnosis was based on direct demonstration of the yeast with characteristic morphology in clinical material, isolation from an arterial thrombus and detection of cryptococcal antigen in the serum. The patient's infection could not be resolved despite institution of antifungal therapy.

The purpose of this review is to focus on the location and the adhesion activity of the protein (peptide) and the mannan moieties of the mannoprotein in the outer surface of the Candida albicans cell wall. A macromolecule of the mannoprotein located on the outermost surface is undoubtedly a strong adhesin comprising several adhesion molecules including protein and mannan. Mannoproteins can be divided into two classes, higher molecular weight peptidomannans (260 kDa) and lower molecular weight mannoproteins (50-66 kDa), both of which consist of similar mannans and disparate proteins or peptides which have distinct adhesion specificities. The protein moiety of mannoprotein can be divided functionally into two groups, lectin-like proteins and proteins recognizing arginine-glycine-aspartic acid (RGD) ligands. The latter proteins are further subdivided into two groups, CR2/CR3-like proteins and proteins binding extracellular matrix (ECM) proteins. Hydrophobicity of the cell surface of C. albicans influences adhesion of the organisms to epithelial cells. Degree of glycosylation of cell surface mannoproteins that affect yeast cell surface hydrophobicity affects adhesion of C. albicans to epithelial cells. The hydrophobic proteins may have low levels of glycosylation, and changes in glycosylation may determine exposure of hydrophobic protein regions at the cell surface. The serotype A-specific oligosaccharide of antigen 6 (pentaose or hexaose of mannan moiety) has been shown to exhibit marked adhesion ability for epithelial cells, and mannotetraose related to antigenic factor 5 which is present in both serotypes A and B showed adhesive activity for tissue macrophages. Proteinoceous adhesins of C. albicans are expressed preferably on the mycelial form. It is suggested that several of the adhesion molecules of C. albicans described above appear to complementarily utilize multiple adhesion mechanisms.