Candida albicans Germ-Tube Antibody: Evaluation of a New Automatic Assay for Diagnosing Invasive Candidiasis in ICU Patients

Abstract

Testing for Candida albicans germ-tube antibody IFA IgG assay (CAGTA) is used to detect invasive candidiasis infection. However, most suitable assays lack automation and rapid single-sample testing. The CAGTA assay was adapted in an automatic monotest system (invasive candidiasis [CAGTA] VirClia IgG monotest (VirClia), a chemiluminescence assay with ready-to-use reagents that provides a rapid objective result. CAGTA assay was compared with the monotest automatic VirClia assay in order to establish the diagnostic reliability, accuracy, and usefulness of this method. A prospective study with 361 samples from 179 non-neutropenic critically ill adults patients was conducted, including 21 patients with candidemia, 18 with intra-abdominal candidiasis, 84 with Candida spp. colonization, and 56 with culture-negative samples, as well as samples from ten healthy subjects. Overall agreement between the two assays (CAGTA and VirCLIA) was 85.3%. These assays were compared with the gold-standard method to determine the sensitivity, specificity as well as positive and negative predictive values. In patients with candidemia, values for CAGTA and VirCLIA assays were 76.2 versus 85.7%, 80.3 versus 75.8%, 55.2 versus 52.9%, and 91.4 versus 94.3%, respectively. The corresponding values in patients with intra-abdominal candidiasis were 61.1 versus 66.7%, 80.3 versus 75.8%, 45.8 versus 42.9%, and 88.3 versus 89.3%, respectively. No differences were found according to the species of Candida isolated in culture, except for Candida albicans and C. parapsilosis, for which VirClia was better than CAGTA. According to these results, the automated VirClia assay was a reliable, rapid, and very easy to perform technique as tool for the diagnosis invasive candidiasis.

Diagnosing Invasive Candidiasis

“…Data are less extensive for CAGTA, which detects responses against a hyphal protein (Hwp1) expressed during tissue invasion and biofilm formation (8). The sensitivity and specificity of CAGTA for invasive candidiasis have ranged from 42% to 96% and 54% to 100%, respectively, in different reports (8)(9)(10)(11). In one study, CAGTA sensitivity was 69% for candidemia complicated by deep-seated candidiasis, compared to only 5% for candidemia in the absence of deep-seated candidiasis (8).…”

Non-Culture Diagnostics for Invasive Candidiasis: Promise and Unintended Consequences

“…There is less experience with CAGTA, which detects responses against a hyphal protein (Hwp1) expressed during tissue invasion and biofilm formation [ 6 ]. The sensitivity and specificity of CAGTA for invasive candidiasis have ranged from 42–96% and 54–100%, respectively, in different reports [ 6 , 7 , 8 , 9 ]. In one study, CAGTA sensitivity was 69% for candidemia complicated by deep-seated candidiasis, compared to only 5% for candidemia in the absence of deep-seated candidiasis [ 6 ].…”

“…In one study, CAGTA sensitivity was 69% for candidemia complicated by deep-seated candidiasis, compared to only 5% for candidemia in the absence of deep-seated candidiasis [ 6 ]. Across several studies, sensitivity and specificity of CATGA for deep-seated candidiasis ranged from 53–73% and 54–80%, respectively [ 7 , 8 , 9 ]. Sensitivity of CATGA may be lower for infections caused by C. tropicalis than other Candida species.…”

Diagnosis and Treatment of Candidemia in the Intensive Care Unit

“…118,119 Although the hyphal protein was initially found in C. albicans (hence the name of the test), the CAGTA assay can be positive also in IC caused by other Candida species. 20,117,[120][121][122] Experience in the use of CAGTA for IC is limited compared with BDG and Mn/A-Mn. According to the results of a recent meta-analysis of seven studies, 117,119,120,[122][123][124][125] the pooled sensitivity and specificity of CAGTA for the diagnosis of IC were 65% (95% CI: 59-73) and 76% (95% CI: 58-88).…”

“…20,117,[120][121][122] Experience in the use of CAGTA for IC is limited compared with BDG and Mn/A-Mn. According to the results of a recent meta-analysis of seven studies, 117,119,120,[122][123][124][125] the pooled sensitivity and specificity of CAGTA for the diagnosis of IC were 65% (95% CI: 59-73) and 76% (95% CI: 58-88). 126 An important heterogeneity in specificity was detected.…”