Article

Isolation and molecular characterization of Candida africana from Jos, Nigeria.

* Department of Medical Microbiology, University of Jos , Jos , Nigeria.
Medical mycology: official publication of the International Society for Human and Animal Mycology (Impact Factor: 2.13). 03/2012; 50(7):765-7. DOI: 10.3109/13693786.2012.662598
Source: PubMed

ABSTRACT During a survey of the prevalence of Candida spp. in Jos, Plateau State, Nigeria, two atypical C. albicans isolates were recovered. These two yeasts were germ tube positive, chlamydospore-negative and gave a green color on CHROMagar Candida. Molecular analysis performed by amplification of the hwp1 gene showed that these two isolates belonged to C. africana, a newly proposed Candida species closely related to C. albicans. Based on the presence or absence of an intron in DNA sequences encoding rRNA, the two C. africana, including all C. albicans isolates examined, were found to belong to genotype A and no other genotypes or species such as C. dubliniensis were found. To our knowledge, this is the first isolation of C. africana in Nigeria.

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    ABSTRACT: Candida africana was previously proposed as a new species within the Candida albicans species complex, together with C. albicans and C. dubliniensis, although further phylogenetic analyses better support its status as an unusual variant within C. albicans. Here we show that C. africana can be distinguished from C. albicans and C. dubliniensis by Pyrosequencing® of a short region of ITS2, and have evaluated its occurrence in clinical samples by Pyrosequencing® all presumptive isolates of C. albicans submitted to the Mycology Reference Laboratory over a 9 month period. The C. albicans complex constituted 826/1839 (44.9%) of yeast isolates received over the study period and included 783 isolates of C. albicans, 28 isolates of C. dubliniensis and 15 isolates of C. africana. In agreement with previous reports, C. africana was isolated exclusively from genital specimens, in women in the 18-35 years age group. Indeed, C. africana constituted 15/251 (6%) of "C. albicans" isolates from female genital specimens during the study period. C. africana isolates were germ-tube positive, grew significantly more slowly than C. albicans and C. dubliniensis on conventional mycological media, could be distinguished from the other members of the C. albicans complex by appearance on chromogenic agar, and were incapable of forming chlamydospores. Here we present the detailed evaluation of epidemiological, phenotypic and clinical features and antifungal susceptibility profiles of UK isolates of C. africana. Furthermore, we demonstrate that C. africana is significantly less pathogenic than C. albicans and C. dubliniensis in the Galleria mellonella insect systemic infection model.
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    ABSTRACT: Candida speciation is vital for epidemiology and management of candidiasis. Nonmolecular conventional methods often fail to identify closely related germ tube positive yeasts from clinical specimens. The present study was conducted to identify these yeasts and to highlight issues in conventional versus molecular methods of identification. A total of 98 germ tube positive yeasts from high vaginal swabs were studied over a 12-month period. Isolates were examined with various methods including growth at 42°C and 45°C on Sabouraud dextrose agar (SDA), color development on CHROMagar Candida medium, chlamydospore production on corn meal agar at 25°C, carbohydrate assimilation using ID 32C system, and polymerase chain reaction using a single pair of primers targeting the hyphal wall protein 1 (Hwp1) gene. Of all the isolates studied, 97 were molecularly confirmed as C. albicans and one isolate was identified as C. dubliniensis. No C. africana was detected in this study. The molecular method used in our study was an accurate and useful tool for discriminating C. albicans, C. dubliniensis, and C. africana. The conventional methods, however, were less accurate and riddled with many issues that will be discussed in further details.
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    ABSTRACT: Twelve years ago, Candida africana was proposed as new species within the Candida albicans species complex, and since then has raised much controversy regarding whether or not it should be considered a separate species from C. albicans. Although its taxonomic status is still a matter of debate, this yeast differs from C. albicans by a number of phenotypic, genotypic, pathogenic and clinical characteristics that make this fungus particularly interesting to study. Current epidemiological and clinical data suggest that C. africana has a worldwide distribution, is particularly adapted to colonize/ infect human vaginal mucosa, and may also be responsible for most serious diseases involving other human organs. In this review, we will discuss the current knowledge about C. africana, highlighting its role in human infections, thus providing a complete clinical picture in order to understand if this yeast can be considered an important pathogen.
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