Epidemiology, Antifungal Susceptibility, and Pathogenicity of Candida africana Isolates from the United Kingdom

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 we 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 826/1,839 (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-to-35-year 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 United Kingdom 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.

Comparison of the in vitro activity of echinocandins against Candida albicans , Candida dubliniensis , and Candida africana by time–kill curves

“…One of the limitations of the current study is the scarce number of C. africana isolates tested due to the low frequency of isolation in the clinical setting (1.8%) (Borman et al, 2013). Nevertheless, the identification of C. africana, C. albicans, and C. dubliniensis is important because these species show different susceptibility to echinocandins, even within the same species, for this reason, when an antifungal treatment fails, it may be due to the fact that different isolates of the same species do not respond equally to antifungals.…”

“…Our study suggests that C. albicans is the most susceptible species for echinocandins, followed by C. dubliniensis and C. africana. However, the latter species is less pathogenic than C. albicans and C. dubliniensis in the Galleria mellonella systemic infection model, according to Borman et al (2013).…”

Usefulness of MALDI-TOF Mass Spectrometry for Routine Identification of Candida Species in a Resource-Poor Setting

“…For the identification of C. dubliniensis, it is a lack of the machine and it can be solved by the update of the database by introducing new references strains of this species. But in the case of C. africana, it has been already reported in the literature that current matrixassisted laser desorption/ionization time-of-flight mass spectrometry approaches are apparently unable to robustly distinguish C. africana and C. albicans [26]. So, it seems that the molecular methods are currently the appropriate tools for the discrimination of C. africana and C. albicans [16].…”

Are the Conventional Commercial Yeast Identification Methods Still Helpful in the Era of New Clinical Microbiology Diagnostics? A Meta-Analysis of Their Accuracy

“…The Vitek 2 system, using the ID-YST (fluorimetric) card and the newly developed YST (colorimetric) card, incorporates a database that has been unmodified since 2000, with 52 identifiable yeast species. It is noteworthy that the systems' databases have been progressively updated to cover taxa of common and uncommon clinical species, but their performance should be continually monitored to determine whether these systems are actually capable of keeping up with the appearance of rare or novel pathogenic species (18,19) and possibly with the geographic or source variations of clinical isolates (20).…”