Levels of (1→3)-β-D-glucan, Candida mannan and Candida DNA in serum samples of pediatric cancer patients colonized with Candida species

<p>Abstract</p> <p>Background</p> <p>Surveillance cultures may be helpful in identifying patients at increased risk of developing invasive candidiasis. However, only scant information exists on the effect of <it>Candida </it>colonization on serum levels of diagnostic biomarkers. This prospective surveillance study determined the extent of <it>Candida </it>colonization among pediatric cancer patients and its possible impact on serum levels of (1-3)-β-D-glucan (BDG), <it>Candida </it>mannan and <it>Candida </it>DNA.</p> <p>Methods</p> <p>A total of 1075 swabs originating from oropharynx (n = 294), nostrils (n = 600), rectum (n = 28), groin (n = 50), ear (n = 54), and axilla (n = 49) of 63 pediatric cancer patients were cultured for the isolation of <it>Candida </it>spp. Patients yielding <it>Candida </it>spp. from any sites were considered as colonized. Serum samples were collected from patients at the time of first surveillance culture for detection of BDG by Fungitell kit and <it>Candida </it>mannan by Platelia <it>Candida </it>Ag. <it>Candida </it>DNA was detected by using panfungal primers and identification was carried out by using species-specific primers and DNA sequencing.</p> <p>Results</p> <p>Seventy-five (7.6%) swab cultures from 35 (55.5%) patients yielded <it>Candida </it>spp. These isolates included <it>C. albicans </it>(n = 62), <it>C. dubliniensis </it>(n = 8), <it>C. glabrata </it>and <it>C. tropicalis </it>(n = 2 each) and <it>C. krusei </it>(n = 1). Eleven patients were colonized at three or more sites. Eight of 36 serum samples from 6 colonized patients yielded BDG values higher than the currently recommended cut-off value of ≥80 pg/ml. However, none of the serum samples yielded <it>Candida </it>mannan levels ≥0.5 ng/ml and PCR test for <it>Candida </it>DNA was also negative in all the serum samples of colonized patients. During the study period, only two colonized patients subsequently developed candidemia due to <it>C. tropicalis</it>. Besides positive blood cultures, <it>C. tropicalis </it>DNA, BDG and <it>Candida </it>mannan were also detected in serum samples of both the patients.</p> <p>Conclusions</p> <p>The present study demonstrates that while mucosal colonization with <it>Candida </it>species in pediatric cancer patients is common, it does not give rise to diagnostically significant levels of <it>Candida </it>mannan or <it>Candida </it>DNA in serum specimens. However, BDG values may be higher than the cut-off value in some pediatric patients without clinical evidence of invasive <it>Candida </it>infection. The study suggests the utility of <it>Candida </it>mannan or <it>Candida </it>DNA in the diagnosis of invasive candidiasis, however, the BDG levels in pediatric cancer subjects should be interpreted with caution.</p

Calcineurin-dependent galactomannan release in Aspergillus fumigatus

Item does not contain fulltextThe galactomannan assay to diagnose invasive aspergillosis is recommended and clinically utilized, yet the mechanism of galactomannan release from Aspergillus fumigatus is unknown. We used an A. fumigatus strain lacking calcineurin A (cnaA), already shown to be critically important for pathogenicity, to evaluate galactomannan kinetics. During the logarithmic growth phase when glucose was consumed, beta-D-galactofuranoside (galf)-antigens were released in the culture. However, after glucose became limited, GM release further increased in the supernatants of the wild type strain while there was no further increase of GM release in the DeltacnaA strain. beta-Galactofuranosidase activity was also decreased in the DeltacnaA mutant, and the amount of galf-antigen in the cell wall fraction of the DeltacnaA mutant was approximately ten-fold higher. This suggests the possibility that the antigen is unable to be released due to a cell wall abnormality. This and previous work suggest a dynamic calcineurin-dependent cell wall during periods of growth, with galactomannan release from the cell wall possibly calcineurin-dependent and reflected in the decreased GM release and greatly increased cell wall fraction of galf in the DeltacnaA mutant

Performance of the new Platelia Candida Plus assays for the diagnosis of invasive Candida infection in patients undergoing myeloablative therapy

Item does not contain fulltextThe performance of the new Platelia Candida Antigen Plus (Ag Plus) and Antibody Plus (Ab Plus) assays (Biorad Laboratories, France) was evaluated using a collection of serum samples obtained from 21 patients with microbiologically proven invasive candidiasis and 30 control patients who were being treated with myeloablative chemotherapy, and the data compared with that obtained with the earlier version of the Platelia Candida assays (Ag and Ab), and 1,3-ss-D-glucan (BG) detection systems. The sensitivity of the Ag Plus and Ab Plus assays in the per patient analysis ranged from 55-70% and from 30-64% for patients with less than 15 days of neutropenia and more than 15 days of neutropenia, respectively. Sensitivity and time to detection of these new assays was not significantly better than of the conventional Platelia Candida tests. However, the specificity of the Ag-Plus assay was reduced by approximately 50% as compared to the Ag assay. Logistic regression analysis showed that this was probably due to the fact that circulating mannan was also being detected by the Ag Plus assay in patients with superficial candidiasis. Further studies are needed to confirm our results and to determine the place of the Platelia Ag Plus and Ab Plus assays in the management of haematology patients at risk for Candida infections

Optimization of the cutoff value for the Aspergillus double-sandwich enzyme immunoassay.

Contains fulltext : 53422.pdf (publisher's version ) (Open Access)BACKGROUND: Many health care centers worldwide use the Platelia Aspergillus enzyme immunoassay (PA-EIA; Bio-Rad Laboratories) for diagnosis of invasive aspergillosis (IA). A cutoff optical density (OD) index of 1.5 was originally recommended by the manufacturer, but in practice, most institutions use lower cutoff values. Moreover, a cutoff OD index of 0.5 was recently approved in the United States. In the present study, we set out to optimize the cutoff level by performing a retrospective analysis of PA-EIA values for samples that had been obtained prospectively from adult patients at risk for IA at 2 European health care centers. METHODS: In total, 239 treatment episodes were included of which there were 19 episodes of proven IA and 19 episodes of probable IA. Per-episode and per-test analyses and receiver operating characteristic curves were used to determine the optimal cutoff value. RESULTS: In the per-episode analysis, lowering the cutoff OD index for positivity from 1.5 to 0.5 increased the overall sensitivity by 21% (from 76.3% to 97.4%) but decreased the overall specificity by 7% (from 97.5% to 90.5%). Requiring 2 consecutive samples with an OD index > or = 0.5 resulted in the highest test accuracy, with an improved positive predictive value. At a cutoff OD index of 0.5, the antigen test result was positive during the week before conventional diagnosis in 65% of cases and during the week of diagnosis in 79.5% of cases. CONCLUSIONS: A cutoff OD index of 0.5--identical to the approved cutoff in the United States--improves the overall performance of the PA-EIA for adult hematology patients

Paradoxical increase in circulating Aspergillus antigen during treatment with caspofungin in a patient with pulmonary aspergillosis.

Contains fulltext : 50418.pdf (publisher's version ) (Open Access)A paradoxical increase in circulating Aspergillus antigen was observed during treatment with caspofungin in a patient with proven invasive aspergillosis. With the exception of treatment with the echinocandin, no other factors were found that might explain this clinical observation, which was supported by experiments done in vitro