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Biomedical subjects

Sanjay G Revankar

Publications and source records attributed to Sanjay G Revankar.

9 recordsLinked to original sources

Phaeohyphomycosis.

Phaeohyphomycosis is an uncommon infection, but has become increasingly recognized in a wide variety of clinical syndromes. Many species are associated with human infection, though a few are responsible for most cases. Because these are typically soil organisms and common laboratory contaminants, they are often disregarded from clinical specimens as non-pathogenic. The clinical setting in which they are isolated, however, should always be carefully considered before making decisions regarding therapy. Bipolaris and Curvularia are often associated ith allergic disease. Diagnosis depends on a high degree of clinical suspicion and appropriate pathologic and mycologic examination of clinical specimens. Therapy is evolving for many of the clinical syndromes described, and randomized clinical trials are unlikely given the sporadic nature of cases. Case reporting of successful and unsuccessful clinical experiences is important in attempting to better define optimal therapy for the more refractory infections. Itraconazole and voriconazole demonstrate the most consistent in vitro activity against this group of fungi. Itraconazole should be considered the drug of choice for most situations, given the greater clinical experience associated with its use for these infections. Given the lack of comparative clinical data, however, decisions over which azole to use in particular setting are largely empiric. Much additional work is needed to better understand the pathogenic mechanisms underlying phaeohyphomycosis and optimize therapy for these often refractory infections.

Antifungal Agents↗

Therapy of infections caused by dematiaceous fungi.

Dematiaceous fungi are responsible for a wide variety of clinical syndromes, from local infections due to trauma, to disseminated infection in immunocompromised patients. These fungi are unique owing to the presence of melanin in their cell walls, which imparts the characteristic dark color to their spores and hyphae. Melanin may also be a virulence factor in these fungi. Therapy depends upon the clinical syndrome. Local infection may be cured with excision alone, while systemic disease is often refractory to therapy. Azoles such as itraconazole and voriconazole have the most consistent in vitro activity, although newer agents may also play a role in therapy in the future.

Antifungal Agents↗

Dematiaceous fungi.

Dematiaceous fungi are the etiologic agents of phaeohyphomycosis and are increasingly recognized as causing disease in humans. A wide variety of infectious syndromes are seen, from local infections due to trauma to widely disseminated infection in immunocompromised patients. Pulmonary disease may be divided into allergic bronchopulmonary and nonallergic syndromes, depending on the species. These fungi have unique pathogenic mechanisms owing to the presence of melanin in their cell walls, which imparts the characteristic dark color to their spores and hyphae. Melanin is a known virulence factor in certain fungi, including Cryptococcus neoformans and Wangiella dermatitidis. Therapy depends upon the clinical syndrome. Local infection may be cured with excision alone, whereas systemic disease is often refractory to therapy. Azoles such as itraconazole and voriconazole have the most consistent in vitro activity, though there is more clinical experience with itraconazole. Further studies are needed to better understand the pathogenesis and treatment of these uncommon infections.

Journal Article↗

Genetic diversity of human pathogenic members of the Fusarium oxysporum complex inferred from multilocus DNA sequence data and amplified fragment length polymorphism analyses: evidence for the recent dispersion of a geographically widespread clonal lineage and nosocomial origin.

Fusarium oxysporum is a phylogenetically diverse monophyletic complex of filamentous ascomycetous fungi that are responsible for localized and disseminated life-threatening opportunistic infections in immunocompetent and severely neutropenic patients, respectively. Although members of this complex were isolated from patients during a pseudoepidemic in San Antonio, Tex., and from patients and the water system in a Houston, Tex., hospital during the 1990s, little is known about their genetic relatedness and population structure. This study was conducted to investigate the global genetic diversity and population biology of a comprehensive set of clinically important members of the F. oxysporum complex, focusing on the 33 isolates from patients at the San Antonio hospital and on strains isolated in the United States from the water systems of geographically distant hospitals in Texas, Maryland, and Washington, which were suspected as reservoirs of nosocomial fusariosis. In all, 18 environmental isolates and 88 isolates from patients spanning four continents were genotyped. The major finding of this study, based on concordant results from phylogenetic analyses of multilocus DNA sequence data and amplified fragment length polymorphisms, is that a recently dispersed, geographically widespread clonal lineage is responsible for over 70% of all clinical isolates investigated, including all of those associated with the pseudoepidemic in San Antonio. Moreover, strains of the clonal lineage recovered from patients were conclusively shown to genetically match those isolated from the hospital water systems of three U.S. hospitals, providing support for the hypothesis that hospitals may serve as a reservoir for nosocomial fusarial infections.

Animals↗

Primary central nervous system phaeohyphomycosis: a review of 101 cases.

Phaeohyphomycosis refers to infections caused by darkly pigmented fungi. These fungi rarely cause life-threatening disease. We reviewed 101 cases of culture-proven primary central nervous system phaeohyphomycosis reported in the English-language literature from 1966 to 2002. The most frequently isolated species was Cladophialophora bantiana. The next most frequent isolate was Ramichloridium mackenziei, seen exclusively in patients from the Middle East. More than one-half of the cases occurred in patients with no known underlying immunodeficiency. Mortality rates were high regardless of immune status. Therapy is not standardized, although the combination of amphotericin B, flucytosine, and itraconazole may improve survival rates. Newer azoles, such as voriconazole, also have a broad spectrum of activity against these fungi, although clinical experience is limited. Complete excision of brain lesions may provide better results than simple aspiration. An aggressive medical and surgical approach is warranted in treating these infections to optimize outcomes.

Adolescent↗

Clinical implications of mycotoxins and Stachybotrys.

There has been considerable interest and concern in recent years regarding the potential health effects of mycotoxins in the indoor environment. Although the existence of mycotoxins has been known for several decades, relatively little is known about their effects in humans. What is known comes almost exclusively from studies of ingestion as the route of exposure. This review summarizes what is known regarding health effects of mycotoxins in general and specifically examines the evidence for the role of indoor exposure to the fungi of the genus Stachybotrys as a cause of disease in humans. Much work remains to be done in the area of mycotoxin research. The risk of health effects from ingestion seems much more widespread than from indoor airborne exposure, although the latter has received considerably more media attention. Rigorously controlled studies are needed to clarify these issues.

Aflatoxins↗

Nosocomial outbreak of Exophiala jeanselmei fungemia associated with contamination of hospital water.

From December 1996 through September 1997, we diagnosed 19 cases of fungemia due to Exophiala jeanselmei. We conducted a matched case-control study in which we cultured specimens of blood products, intravenous solutions, and water from a hospital water system. Isolates from environmental cultures were compared to those recovered from patients by random amplification of polymorphic DNA (RAPD). Multivariate analysis showed that neutropenia, longer duration of hospitalization, and use of corticosteroids were risk factors for infection. Environmental cultures yielded E. jeanselmei from 3 of 85 sources: deionized water from the hospital pharmacy, 1 water tank, and water from a sink in a non-patient care area. Use of deionized pharmacy water to prepare antiseptic solutions was discontinued, and no additional cases of infection occurred. RAPD typing showed that isolates from case patients and isolates from the pharmacy water were highly related, whereas the patterns of isolates recovered from the 2 other sources of water were distinct.

Adolescent↗

Disseminated phaeohyphomycosis: review of an emerging mycosis.

Disseminated phaeohyphomycosis is an uncommon infection caused by dematiaceous fungi, although the number of case reports about this infection has been increasing in recent years. A total of 72 cases are reviewed. Scedosporium prolificans is by far the most common cause. The presence of melanin in their cell walls may be a virulence factor for these fungi. The primary risk factor is decreased host immunity, although cases in apparently immunocompetent patients have been reported. Eosinophilia was seen in 11% of cases. Endocarditis is mostly reported on bioprosthetic valves, particularly those of porcine origin. The outcome of antifungal therapy remains poor, with an overall mortality rate of 79%. Special precautions taken for immunocompromised patients may help prevent exposure to fungi during the patients' period of greatest risk. The development of newer antifungal agents and combination therapy may hold promise in improving the management of these devastating infections in the future.

Adolescent↗

Proteinase detection, DNA typing and antimycotic susceptibility of Candida isolates from Colombian women with vulvovaginal candidiasis.

Forty non-pregnant Colombian women (ages 18-45) with vulvovaginal candidiasis diagnosis (VVC) were enrolled in a blinded study to compare the efficacy of Itraconazole (ITRA) 400 mg vs. Fluconazole (FLU) 150 mg. Sexual partners received similar therapy. Proteinase detection by the Staib method and minimal inhibitory concentration (MIC) for FLU and ITRA by Etest method were performed in all Candida isolates. Patients were followed one year to determine clinical evolution and recurrence of VVC (RVVC). The strain identity of the RVVC isolates was determined by contour-clamped homogeneous electric field (CHEF) gel electrophoresis karyotyping and restriction fragment length polymorphism (RFLP). Thirty patients (75%) had one or two episodes of VVC/year, 83% of these were due to Candida albicans, while ten patients (25%) developed RVVC (three or more episodes/year); seven of them were treated with FLU. Non-C. albicans Candida species were detected in five of 30 (17%) of the patients with VVC and in seven of ten (70%) patients with RVVC (p=0.003). Isolates from nineteen patients were proteinase positive. Proteinase production and type of treatment were not related to recurrence of VVC (p>0.05). DNA typing revealed that in this population RVVC might be due to the same strain, substrain shuffling or different strains and species.

Journal Article↗