摘要:

Yeasts occur commonly in the oral cavity in healthy individuals. The prevalent species isCandida albicans(about 60–70% of all isolates).C. glabrataandC. tropicaliscome next, followed by otherCandidaspecies and genera(Rhodotorula, Saccharomyces, etc.) which are all of rare occurrence and transient. The yeast flora increases in many patient groups, especially those who are immunocompromised.C. albicansis the most important species, being the cause of almost all cases of yeast infections in the region, often in association with other species. The number isolated from the oral cavity depends on testing site and methods used.C. albicanscan be typed by means of serology (types A and B), by biotyping, by morphology, by means of sensitivity to killer factors, by electrophoretic karyotyping, DNA fragments, and immunoblotting. Such methods may be of value epidemiologically. Switching inCandidamorphology is associated with changes in micromorphology and physiology. Several non-yeast fungi may affect the oral cavity, most frequently in association with lung or disseminated infections.

ISSN:0001-6357    

DOI:10.3109/00016359009012728

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Conventional oral specimens for recovery of yeasts are swabs and smears. Oral rinses and imprint/impression cultures can also be used. Yeasts grow well at room temperature and may multiply in specimens under transport. Direct smears examined for blastospores, hyphae, and inflammatory cells ensure rapid presumptive diagnosis. Fungal identification requires culture, preferably on different media and at different temperatures to ensure recognition of all species present. YM agar supplemented with 0.01% aniline enables detection ofCandida albicansandC. parapsilosison primary plates through fluorescence. Microstix-Candida or Oricult-N slides can be read after culture at room temperature. Histologic sections for demonstration of yeasts require periodic acid-Schiff, Gridley, or Gomori's methenamine silver staining. Fungiqual staining enables non-specific diagnosis, also of rare oral mycoses, within 30min, through fluorescence. Calcofluor white is even faster (<30sec). Specific antibodies labeled with fluorescent stain enable more precise mycologic diagnosis. Mycologic findings should be interpreted together with clinical findings.

ISSN:0001-6357    

DOI:10.3109/00016359009012729

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

The present review deals with chemotaxonomic methods for yeasts. DNA base composition, which is expressed as molar percentages of guanine plus cytosine (G+C), is fitted for description of a new species and serves exclusionary functions. G+C content range among species within a genus is often 10% or less. Larger ranges may indicate an amalgam of genera. Typing and mapping of DNA may also be used for taxonomy. Strains showing 65% or greater relatedness after DNA-DNA hybridization may be considered members of the same species. With rRNA-DNA homology assessment, intrageneric relationships established are not usually meaningful, but intergeneric distances can be resolved. rRNA can be used for examining phylogenetic diversity of yeasts and alloenzyme variation to calculate genetic distances among large yeast populations. Furthermore, heterogeneity in coenzyme Q pattern, cytochrome spectra, composition of cell wall glucan, mannan, and chitin, and cellular fatty acids may serve chemotaxonomic purposes.

ISSN:0001-6357    

DOI:10.3109/00016359009012730

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Methods used for identification and sensitivity testing of yeasts are presented. Identification depends on both morphologic features and biochemical characteristics. The germ tube test is a simple test for the identification of the commonest yeast pathogen,Candida albicans.Species not identified by this method can be identified by means of several other tests, the most important being the carbohydrate assimilation test. Several kits are commercially available and most appear to be satisfactory. Antifungal susceptibility tests are not standardized, and results are often subject to considerable variation. Until improved methods are developed, it might be advisable that smaller laboratories only do a preliminary screening test for flucytosine susceptibility and, if indicated, also for amphotericin B susceptibility. Important isolates should be sent to laboratories with a special interest in antifungal susceptibility testing for more extensive testing

ISSN:0001-6357    

DOI:10.3109/00016359009012731

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

For diagnostic purposes it is normally not important to obtain a biopsy specimen, since an oral smear from the lesion will yield blastospores and pseudohyphae in abundance. However, in lesions that respond poorly to antimycotic treatment a biopsy should be carried out to detect possible malignant changes in the epithelium. Assessment of cell-mediated immunity againstCandida albicansand other antigens may be important in patients with severe chronic candidosis to assess the degree of immunocompetence and prognosis. Usually, patients with oral candidosis show only moderately elevated antibody titers in serum and saliva againstC. albicans, and serologic tests are normally not a diagnostic tool for oral candidosis. However, such tests may be a prognostic instrument in patients with severe oral candidosis who respond poorly to antimycotic therapy.

ISSN:0001-6357    

DOI:10.3109/00016359009012732

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Oral adhesion of yeasts probably occurs by interaction between yeast cell adhesins and oral epithelial cell receptors. InCandida albicansmannoprotein, glucan, chitin, cell wall proteins, and lipids are possible adhesins. Mannoprotein appears as a fibrillar or floccular outermost layer in stationary-phase cells grown in sugar-rich medium. Preincubation of buccal epithelial cells (BECs) with concanavalin A inhibits adhesion, as does suppression of mannoprotein production by tunicamycin. Germ tubes adhere more easily to BECs and plastic than do blastospores. Methyl-α-d-mannoside may be analogous to the yeast adhesin or epithelial cell receptor because it inhibits adhesion ofC. albicansto BECs. l-Fucose,N-acetyl-d-glucosamine, or d-mannose, having the same effect, may also function as epithelial cell receptors. Other factors affecting yeast adhesion may be fibronectin, hydrophobicity, s-IgA, and indigenous bacteria. Growth of yeasts to stationary phase in sugar-rich media promotes adhesion to acrylic, as do divalent cations and serum. Saliva, chlorhexidine, andStreptococcus salivariusinhibit adhesion of yeasts.

ISSN:0001-6357    

DOI:10.3109/00016359009012733

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

By tradition oral candidosis has been classified into acute pseudomembranous (thrush), acute atrophic, chronic atrophic, and chronic hyperplastic types. However, pseudomembranous candidosis is not always acute but may last for many months. Furthermore, the value of using the term atrophic to describe an erythematous area is limited. Moreover, some of the various types have been associated with other clinical entities, which appear to have a combined bacterial/mycologic etiology. A revision of the classification should be based on the use of clinical terms, and in a previous study of multifocal oral candidosis, erythematous, plaquelike, and nodular forms were identified. A revised classification of oral candidosis which considers these aspects could be as follows: acute types: pseudomembranous and erythematous; chronic types: pseudomembranous, erythematous, plaque-like, and nodular; andCandida-associatedlesions: denture stomatitis, angular cheilitis, and median rhomboid glossitis.

ISSN:0001-6357    

DOI:10.3109/00016359009012734

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

Etiologic factors in oral candidosis are immature antimicrobial host defenses, acquired suppression of immune defense mechanisms (AIDS, immunosuppressive or radiation therapy), or changes of the environmental conditions of the oral cavity (antibiotics, dentures, epithelial changes). After colonization and adhesion ofCandidato the epithelial surface the subsequent mucosal lesion is due to tissue destruction by potent proteolytic enzymes or toxins and an inflammatory response toCandidaantigens. Topical antimycotic treatment with nystatin, amphotericin B, or miconazole is important especially to prevent spread of the infection. ChronicCandidainfections require long-term antifungal therapy, and patient compliance may be difficult to obtain. In denture stomatitis colonization of the fitting denture surface byCandidashould be controlled by, for example, using a chlorhexidine solution as a denture disinfectant. However, recurrences are frequent if the local or the systemic predisposing conditions are not corrected. Fluconazole, a new bis-triazole, may be important for long-term treatment of immunocompromised patients.

ISSN:0001-6357    

DOI:10.3109/00016359009012735

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

The discussion of factors predisposing to oral yeast infections is very important, and we can ask: what is primary and what is secondary? Without predisposing factors it is difficult to have oral yeast infections, and a yeast infection may also be the first sign of a developing basic illness. As long as the predisposing factors cannot be eliminated, recurrences of oral yeast infections are to be expected. We can say that local and systemic factors permit this microorganism to cause disease and that it is extremely rare to find a case of oral candidosis in which one or more of these factors cannot be identified. There are many kinds of lists in the textbooks and some review articles in the literature, but more research is needed for better understanding of factors predisposing to oral yeast infections.

ISSN:0001-6357    

DOI:10.3109/00016359009012736

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor

摘要:

The number of immunocompromised patients has increased during recent years. Most fungal infections in these patients are caused byCandida, Aspergillus, Mucor, andCryptococcusspecies. Patients with low granulocyte count are at the highest risk of invasive candidal infection. The commonest type of granulocytopenia is observed in connection with malignant diseases of the hematopoietic system. Cytotoxic treatment and radiotherapy of large-body areas tend to produce a significant decrease in circulating granulocytes. Early diagnosis and adequate treatment of fungal infections are mandatory for a successful outcome. In the oral cavity it is important to differentiate between colonization and invasive infection. The optimal approach to diagnosis is a combination of histology and cultivation of specimens obtained from the same site of suspected infection. Prophylaxis of oral fungal infection in immunocompromised patients is generally aimed at preventing colonization.

ISSN:0001-6357    

DOI:10.3109/00016359009012737

出版商:Taylor&Francis    

年代:1990

数据来源: Taylor