Invasive candidiasis: A review of nonculture-based laboratory diagnostic methods

Abstract

Invasive candidiasis is a life-threatening complication of critically ill immunocompromised patients with high attributable mortality. Due to non-specific clinical presentation, early detection of candidemia and accurate identification of Candida species are essential pre-requisites for improved therapeutic outcome. Since blood culture-based methods lack sensitivity and species-specific identification by conventional methods is time-consuming, detection of immunological and molecular markers has provided an alternative for early diagnosis of invasive candidiasis. Additionally, serial estimations of these biomarkers have provided opportunities to monitor response to therapy and initiate pre-emptive therapy in suspected patients before clinical signs appear. Antigen-based methods include detection of β-D-glucan, a panfungal marker, and Candida mannan, a genus-specific marker. Although both these markers have moderate sensitivity, they provide a useful adjunct to the diagnosis if performed in select patient population in parallel for exclusion of false positive/negative results. A negative β-D-glucan test on at least two occasions has a high negative predictive value. Concomitant detection of Candida mannan and anti-mannan antibodies has sensitivity of ~70% before blood cultures become positive. Significant advances have also been made in nucleic acid-based detection methods, including a commercial real-time PCR assay (SeptiFast) for detection of five major clinically important Candida spp. in blood specimens within 6 h. Furthermore, matrix-assisted laser desorption ionization time-of-flight mass spectrometry enables species-specific identification of yeast isolates within an hour. While these immunological and molecular tools mark a significant advance towards early and specific diagnosis of candidemia and invasive candidiasis, further evaluation of these approaches in different clinical settings is warranted.

Candida lusitaniae in Kuwait: Prevalence, antifungal susceptibility and role in neonatal fungemia

“…All positive cultures were Gram-stained and subcultures were made on blood agar and/or Sabouraud dextrose agar. Isolated yeast colonies were processed for routine identification procedures, which included direct microscopic examination by wet mount, Germ tube test, growth characteristics on CHROMagar Candida and identification by Vitek 2 yeast identification system [15]. Laboratory details of all the isolates identified as C .…”

Invasive Fungal Infections in the ICU: How to Approach, How to Treat

“…Moreover in deep-seated candidiasis or in patients under fluconazole prophylaxis, BCs are often negative [36,37]. Newer culture methods have raised the sensitivity of Candida detection to almost 70%, but they require a minimum of 24 to 48 h to become positive and thus their result may come late in the course of the infection [38].…”

“…For the detection of mannan antigen two methods have been described: a latex agglutination test (Pastorex- Candida ; Biorad, Biorad laboratories GmBH); and an enzyme–linked immunosorbent assay (ELISA)(Platelia– Candida ; Biorad). Both methods have equal specificity (90%–100%) in diagnosing candidaemia [38,42] but ELISA has superior sensitivity, ranging between 30%–60%, depending on study population, diagnostic cut–off points and Candida species under consideration, being higher for C. albicans [42,43,44]. In high risk patients, performing the test two to three times per week is highly recommended, since its circulation in the bloodstream is intermittent [21,38].…”

Isolation ofLodderomyces elongisporusfrom the Catheter Tip of a Fungemia Patient in the Middle East

“…It is probable, therefore, that L. elongisporus isolates may be occurring with greater frequency than hitherto recognized due to limitations of currently available phenotypic identification methods. Recent application of molecular methods have resulted in species-specific identification of closely related yeast species including L. elongisporus [21]. Application of molecular methods in one study involving 542 clinical isolates of C. parapsilosis obtained from 25 countries and previously identified by conventional phenotypic methods identified 10 isolates as L. elongisporus .…”