Identification of Candida species by restriction enzyme analysis

Abstract

The frequency of invasive fungal infections has increased substantially during the past two decades and it has become a major cause of morbidity and mortality in immunocompromised patients. Aspergillosis, candidiasis, cryptococcosis, and zygomycosis are the main invasive fungal infections observed in these patients (1). Among the fungal pathogens, Candida species are the most common cause of invasive fungal infections (2,3). Candida species rank as the fourth most common cause of nosocomial bloodstream infections and the mortality of these infections varies between 33% and 75%. Despite the widespread use of antifungals for prophylaxis and treatment of invasive fungal infections in immunocompromised patients, candidemia remains the most frequent life-threatening fungal disease and is associated with a prolonged hospital stay that results in a rise in costs (4-6). Although Candida albicans is still the most common cause of Candida infections, fluconazole prophylaxis decreased the incidence of C. albicans infections, but this caused an increase in the incidence of non-albicans Candida species like fluconazole-resistant C. glabrata and C. krusei (1,5,7). Increasing incidence of candidemia caused by C. parapsilosis, C. glabrata, C. tropicalis, C. krusei, C. guilliermondii, and C. lusitaniae was also reported. Approximately half of the reported cases of candidemia are now caused by non-albicans Candida species. This has been attributed to the use of fluconazole prophylaxis (8-12). Rapid identification of Candida species isolated from clinical specimens gives information about antifungal susceptibility as well as shedding light on the choice of empirical treatment. For these reasons, rapid, reliable, and accurate identification of isolates is very important. Identification methods such as germ tube test, morphology on Corn Meal Agar with Tween 80, and assimilationfermentation reactions used for the identification of Candida species in routine laboratory settings are timeconsuming and may lead to ambiguous results, but on the other hand genotype-based methods have become of interest in recent years (12,13). Background/aim: The identification of Candida species isolated from clinical specimens provides information about antifungal susceptibility and sheds light on the choice of empirical treatment. In the present study, restriction enzyme analysis of C. albicans and non-albicans Candida species previously identified by conventional methods was done to evaluate the utility of restriction enzyme analysis for more rapid and reliable identification of Candida species. Materials and methods: A total of 146 Candida strains isolated from various clinical specimens and ATCC strains were included. PCR products were digested with MwoI for all species and with BslI for C. parapsilosis and C. tropicalis strains. Results: The strains were identified by conventional methods as 40 C. albicans, 27 C. parapsilosis, 26 C. tropicalis, 25 C. glabrata, 11 C. kefyr, 10 C. krusei, and 7 C. guilliermondii strains. Restriction digestion with MwoI...

Advances in Chemical and Biological Methods to Identify Microorganisms—From Past to Present

“…strains (MwoI for the totally of the species, and BslI for C. parapsilosis and C. tropicalis strains). The restriction digestion with MwoI was able to distinguish between five different species ( C. albicans , C. krusei , C. guilliermondii , C. kefyr , and C. glabrata ), while BslI digestion could distinguish between C. tropicalis and C. parapsilosis [238]. Another study summarized that phenotypic and molecular methods (PCR-RFLP) resulted in the identification of 65.2% and 96.6% of 204 Candida spp.…”

Laboratory Diagnosis of Candidiasis

“…The ITS region of ribosomal DNA (rDNA) is the most useful genetic marker for rapid and accurate molecular identification of Candida species and phylogenetic studies due to its region sequence variability among different species [15,[45][46][47]. The ITS 1 and ITS 2 are two vital non-coding regions composed of conservative and variable subregions outside and inside respectively [45].…”

Candida albicans, from endodontic point of view

“…Biochemical profiling based on vibrational spectroscopy reflects the variability of chromosomal patterns and DNA content of clinical isolates of Candida species and can facilitate diagnosis and targeted therapy of candidiasis [18] . Restriction enzyme analysis with Mwol and BslI can be used for Candida species identification in situations where rapid identification is necessary or conventional methods are problematic [19] . The application of C. albicans microarrays in early studies on pathogenesis, cell biology, antifungal susceptibility and diagnostics confirmed their usefulness, and the results showed good correlations with data obtained with other techniques.…”