Current topics in medical mycology最新文献

{"title":"Emerging zygomycoses of humans: Saksenaea vasiformis and Apophysomyces elegans.","authors":"J Holland","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Since the first isolation of Saksenaea vasiformis and Apophysomyces elegans from soil specimens in 1953 and 1979, respectively, more than 30 human infections have occurred with these organisms. This paper will review the laboratory diagnosis and clinical manifestations of infections with these emerging zygomycetes.</p>","PeriodicalId":77092,"journal":{"name":"Current topics in medical mycology","volume":"8 1-2","pages":"27-34"},"PeriodicalIF":0.0,"publicationDate":"1997-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20428990","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Penicillium marneffei infection in patients infected with human immunodeficiency virus.","authors":"N Vanittanakom,&nbsp;T Sirisanthana","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Opportunistic infections are major causes of morbidity in patients with human immunodeficiency virus (HIV) infection. Penicillium marneffei infection is very common in HIV-infected individuals in northern Thailand. The patients usually present with fever, anemia, weight loss, skin lesions, generalized lymphadenopathy, and hepatomegaly. The average number of CD4+ T-lymphocytes at presentation was 63.8 cells/mm3. Diagnosis depends on familiarity with the clinical syndromes and support from the mycology laboratory. The response to antifungal treatment of the patients is generally good, but depends on the ability of the physician to make the diagnosis and start the treatment early. New approaches to the laboratory diagnosis of P. marneffei infection have been reported. Further study of these approaches may help physicians in taking better care of the patients.</p>","PeriodicalId":77092,"journal":{"name":"Current topics in medical mycology","volume":"8 1-2","pages":"35-42"},"PeriodicalIF":0.0,"publicationDate":"1997-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20428991","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Germ tube growth of Candida albicans.","authors":"N A Gow","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The clinical pathogen Candida albicans is a budding yeast that is capable of forming a range of polarized and expanded cell shapes from pseudohyphae to true nonconstricted hyphae. Filamentous forms consist of contiguous uninucleated compartments that are partitioned by septa. It has long been held that the so-called \"dimorphic transition\" from a budding to a filamentous form may aid the fungus to penetrate epithelia and may therefore be a virulence factor. This review summarized new information regarding the physiology and ecology of hyphal growth in C. albicans. New evidence has demonstrated that hyphae of C. albicans have a sense of touch so that they grow along grooves and through pores (thigmotropism). This may aid infiltration of epithelial surfaces during tissue invasion. Hyphae are also aerotropic and can form helices when contacting solid surfaces. Growing evidence supports the view that hyphal growth is a response to nutrient deprivation, especially low nitrogen and that filamentous growth enables the fungus to forage for nutrients more effectively. Further insights into the growth of C. albicans have come from the analysis of genes and mutations of Saccharomyces which have begun to reveal the molecular mechanisms underlying the mechanisms of bud site selection, cell polarity and signal transduction pathways that lead to pseudohyphal development in this and other organisms. For example, it is now clear that a MAP-kinase cascade, homologous to the mating pathway in Saccharomyces, regulates filamentous growth in both fungi. However, this must be only one of several overlapping or separate signal transduction pathways for hyphal development because filamentous growth still occurs in mutants of Candida and Saccharomyces which are blocked in this pathway. Cell cycle analyses have shown that hyphal phase cell cycle of Candida is distinct from that in budding and pseudohyphal formation and so pseudohyphal growth of Saccharomyces is not a true model of germ tube growth in Candida. Pseudohyphal growth in both Candida and Saccharomyces involves synchronous division of mother cells and their daughters. In contrast, during germ tube growth of Candida, cytoplasm is unequally partitioned at cytokinesis so that apical cells inherit more cytoplasm and sub-apical cells have a single nucleus but are extensively vacuolated. As a result, apical cells grow and divide while sub-apical cells are apparently arrested in the cell cycle until they can regenerate sufficient cytoplasm to re-enter the cell cycle. Although current studies still fall short of verifying the status of yeast-hypha dimorphism as a virulence factor, they suggest that the cell biology of germ tube growth of C. albicans is well suited for the invasive growth of the fungus in vivo.</p>","PeriodicalId":77092,"journal":{"name":"Current topics in medical mycology","volume":"8 1-2","pages":"43-55"},"PeriodicalIF":0.0,"publicationDate":"1997-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20428992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Candida dubliniensis: an emerging opportunistic pathogen.","authors":"D Sullivan,&nbsp;D Coleman","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>The incidence of opportunistic fungal infections continues to increase, partly as a result of the continuing AIDS epidemic. Candida albicans remains the most important fungal pathogen and is frequently associated with oral candidiasis in HIV-infected individuals. Over the past decade, however, there has been an increasing number of reports implicating other Candida species, such as C. tropicalis, C. glabrata and C. krusei, in disease in these patients and in other patient groups. During the same period there have also been frequent reports in the literature describing what have generally been termed \"atypical\" C. albicans strains. These isolates have usually been recovered from symptomatic HIV-infected individuals and are unidentifiable as any recognized Candida species using conventional criteria. Two such groups of isolates recovered from cases of oral candidiasis in Irish and Australian HIV-infected and AIDS patients have been postulated to constitute a novel species which has been termed C. dubliniensis. These isolates are phenotypically very similar to C. albicans in that they produce germ tubes and chlamydospores. However, they have unusual carbohydrate assimilation patterns and grow poorly or not at all at 42 degrees C. Using a variety of DNA fingerprinting techniques and karyotype analysis, the genomic organization of C. dubliniensis was shown to be distinctly different from that of C. albicans. Classification of C. dubliniensis as a separate species was confirmed by phylogenetic analysis, whereby the comparison of ribosomal RNA sequences demonstrated that C. dubliniensis isolates formed a cluster clearly distinct from other Candida species, including C. albicans, to which it is most closely related. Since its original identification, atypical Candida isolates from around the world have been positively identified as belonging to this species. To date, isolates of C. dubliniensis have been recovered mainly from the oral cavities of HIV-infected individuals and are most frequently implicated in cases of recurrent infection following antifungal drug treatment. The clinical importance of this species and the role of drug resistance in its epidemiology have yet to be determined.</p>","PeriodicalId":77092,"journal":{"name":"Current topics in medical mycology","volume":"8 1-2","pages":"15-25"},"PeriodicalIF":0.0,"publicationDate":"1997-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20428989","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Immunochemical study on mannans of genus Candida. I. Structural investigation of antigenic factors 1, 4, 5, 6, 8, 9, 11, 13, 13b and 34.","authors":"S Suzuki","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Since the late 1960s, we have been conducting a series of immunochemical studies on the mannans of the genus Candida with emphasis on the structural determination of antigenic factors composing of the antigenic formula of medically relevant Candida species proposed by Tsuchiya and his colleagues. This review is a chronological account of the structural studies on 10 antigenic factors conducted by two groups of workers: Fukazawa, the senior student of Tsuchiya, and Suzuki.</p>","PeriodicalId":77092,"journal":{"name":"Current topics in medical mycology","volume":"8 1-2","pages":"57-70"},"PeriodicalIF":0.0,"publicationDate":"1997-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20428993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Empirical antifungal therapy in febrile neutropenic patients: current status.","authors":"C C Kibbler","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Empirical antifungal therapy has become established as standard practice in hematology and oncology units over the past decade and its use is increasing. A number of agents have been evaluated and intravenous amphotericin B has emerged as the drug of choice. Evidence of its benefit is limited and only clearly demonstrated in patients not receiving prior antifungal prophylaxis. However, although there have been improvements in the diagnosis of invasive fungal infections, it has been well shown that many patients who die during periods of neutropenia succumb to undiagnosed fungal infection, and also, if treatment is to be effective, it should be started as soon as possible after the onset of infection. Better targeting of antifungal prophylaxis (or preemptive therapy) and empirical therapy may now be possible and standard empirical therapy needs to be reevaluated in the light of changes in the underlying immune status of neutropenic patients and the development of new antifungal agents for prophylaxis and treatment.</p>","PeriodicalId":77092,"journal":{"name":"Current topics in medical mycology","volume":"8 1-2","pages":"5-14"},"PeriodicalIF":0.0,"publicationDate":"1997-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20428988","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Human pythiosis.","authors":"M Thianprasit,&nbsp;A Chaiprasert,&nbsp;P Imwidthaya","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Pythiosis is a cosmopolitan granulomatous disease caused by an aquatic fungus Pythium insidiosum which usually occurs in horses, cattle, dogs, cats or fishes. There have been 28 cases of human pythiosis published in the literature. Twenty three patients have been reported from all over Thailand. Human pythiosis presents in one of three clinical forms: cutaneous or subcutaneous, systemic or vascular and ophthalmic (e.g., corneal ulcer or keratitis). Systemic antibiotics or antimycotics are not effective in the treatment of this infection. A saturated solution of KI gives a beneficial result only in the subcutaneous form. Surgical removal of the source of infection is the method of therapy of vascular and ophthalmic forms.</p>","PeriodicalId":77092,"journal":{"name":"Current topics in medical mycology","volume":"7 1","pages":"43-54"},"PeriodicalIF":0.0,"publicationDate":"1996-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20429077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genomic variation in C. albicans.","authors":"B L Wickes,&nbsp;R Petter","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Candida albicans displays many types of variation which affect a broad spectrum of phenotypes. Among them are antigenic, chromosomal, morphologic, and biochemical variation. The ability to modulate many phenotypes is clearly an important factor in the success of this fungus as a pathogen and variation at the genomic level may be the common denominator among the different systems. Genomic variation in C. albicans has been studied by many researchers and a number of different mechanisms have been identified. Among them are ploidy fluctuations, which allow the organism to cycle from 2n chromosome number to 4n or higher; translocation, which has been demonstrated to involve many different chromosomes and affects many phenotypes including virulence; mitotic recombination, which has been demonstrated to increase resistance to certain drugs; and nondisjunction, which has been shown to have morphological consequences. The number and diversity of these mechanisms combine to make C. albicans a highly successful organism. Although normally a commensal of humans, when invasive, C. albicans can inhabit almost any site in the body. It is not known what governs the transition of C. albicans from a commensal to pathogenic invader, however, variation at the genomic level likely plays a role. One possible consequence of variation is the generation of atypical strains, further expanding the documented phenotypic plasticity of this organism. The exposure of patients to cytotoxic drugs during treatment of such diseases as AIDS or cancer increases the selective pressure and has exacerbated both the frequency and degree of variability observed in C. albicans. The molecular analysis of genomic variation in C. albicans is proving to be a fertile area of research and future investigations can only be expected to add to the mechanisms documented in this review.</p>","PeriodicalId":77092,"journal":{"name":"Current topics in medical mycology","volume":"7 1","pages":"71-86"},"PeriodicalIF":0.0,"publicationDate":"1996-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20428986","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Virulence factors of Cryptococcus neoformans.","authors":"A J Hamilton,&nbsp;J Goodley","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Cryptococcus neoformans is an encapsulated yeast which causes cryptococcosis, a disease typified by an initial pulmonary infection which can disseminate to cause a life threatening meningoencephalitis. Although the disease may occur in individuals who show no evidence of immunosuppression it has had it most significant impact as an infection in patients with AIDS. Research into the potential virulence factors of this yeast has recently attracted particular attention. Capsule synthesis has been the focus of most interest and it is now established as a major virulence determinant. The mechanisms by which the capsule and capsular material effect the immune response have now largely been elucidated, and the genes underlying capsular synthesis are now under investigation. The isolation of mutants incapable of melanogenesis have implicated this process in the pathogenesis of C. neoformans infections, and evidence suggests that the production of melanin protects the yeast against oxidant induced damage. There is also some genetic evidence for the potential involvement of temperature tolerance and mating types in the virulence of this encapsulated yeast. The roles of other potential C. neoformans virulence determinants are more speculative; these include proteinase production, release of polyol metabolites, interaction with hormones, adherence and production of mannoproteins. The involvement of housekeeping enzyme systems in the maintenance of infection by C. neoformans is now also under active investigation.</p>","PeriodicalId":77092,"journal":{"name":"Current topics in medical mycology","volume":"7 1","pages":"19-42"},"PeriodicalIF":0.0,"publicationDate":"1996-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20429076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Candida albicans secreted aspartyl proteinases.","authors":"B Hube","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Evidence suggests that infections with the opportunistic yeast Candida albicans are caused by several factors. Among these virulence attributes, secreted aspartyl proteinases (Saps) are widely believed to play a role during pathogenesis. Sap isoenzymes are encoded by at least eight closely related SAP genes. Antigen-antibody studies provided evidence that Sap isoenzymes are expressed in vivo and experimental infections with proteinase deficient mutants suggested a role for Saps in the virulence of C. albicans. However, only one gene product, Sap2, has been characterized in detail. In vitro studies with purified Sap(2) suggested several possible host targets but the role of each Sap isoenzyme remains unclear. The expression pattern of SAP genes proposed that Sap isoenzymes are secreted simultaneously with morphological changes such as the yeast to hyphal transition or during phenotypic switching. In addition, extracellular proteolytic activity may affect adhesion to host cells and thus may help the fungus to persist on host surfaces and to penetrate into deeper tissue. This review will deal with secretory proteinases from C. albicans as putative virulence factors and will focus on the more recent molecular aspects of the proteinases and their genes. Insights into the genetic organization and regulation of the secreted proteinases suggest not only that these enzymes may act as virulence factors of C. albicans, but that the pathogenesis of this fungus is indeed complex and multifactorial.</p>","PeriodicalId":77092,"journal":{"name":"Current topics in medical mycology","volume":"7 1","pages":"55-69"},"PeriodicalIF":0.0,"publicationDate":"1996-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"20429078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}