Candida Mannan Research Articles

Comparison of β-1-3-D-Glucan and Candida Mannan Biomarker Assays with Serological Tests for the Diagnosis of Candidemia.

Invasive candidiasis, including bloodstream infection (candidemia), encompasses the most severe forms of Candida infection. Several species-specific and non-specific serological assays are commercially available to aid in diagnosis. This study compared the performance of five such biomarker assays. Serum samples from 14 patients with proven or probable invasive candidiasis, and from 10 control patients, were included in the analysis. A total of 50 serum samples were tested using C. albicans germ tube antibody (CAGTA) assay (Vircell), C. albicans IgM, C. albicans IgG and Candida mannan assays (Dynamiker Biotechnology). Among these samples, the β-1-3-D-glucan (BDG) assay (Fungitell), a laboratory standard for the diagnosis of invasive candidiasis, was positive in 20 (40%), intermediate in five (10%) and negative in 25 (50%). In cases of proven or probable candidemia, the sensitivity and specificity of the BDG assay was 86% and 80%, respectively; the Candida mannan assay, 14% and 86%; the CAGTA test, 57% and 60%; the C. albicans IgM assay, 71% and 60%; and C. albicans IgG assay 29% and 90%. In 4/8 (50%) cases with multiple serum samples, C. albicans IgM was positive sooner than BDG. Thus, when used as a rule-out test for invasive candidiasis, our data suggest that the C. albicans IgM assay may assist antifungal stewardship (over serum BDG).

Predictors of Candidemia during Febrile Episode in Lymphoreticular Malignancy Affecting Paediatric Population.

Limited studies on candidemia in malignancy in the paediatric population from developing countries show a high incidence, high morbidity and a unique epidemiology as compared to developed nations. Our prospective observational study aimed to explore the prevalence of invasive candidiasis, especially candidemia, in febrile paediatric patients with lymphoreticular malignancy. A sample size of 49 children, with 100 recorded febrile episodes was studied. The relevance of candida colonization and mannan antigen detection as indicators of impending candidemia was evaluated. Genotypic identification of the yeast isolates was followed by sequence analysis using the NCBI-BLAST program, and the generation of the phylogenetic tree using MEGA 6.0 software. We observed a 5% prevalence of candidemia among febrile paediatric patients with lymphoreticular malignancy, predominantly caused by non-albicans candida. Colonization at multiple anatomical sites decreased from day 1 to day 8 of febrile episodes. Significant candida colonization (colonization index ≥0.5) was seen in a larger proportion of candidemia patients on day 1 and day 4 (p < 0.001) displaying a definite association between the two. The receiver operator characteristic (ROC) curve analysis for mannan antigen level revealed a cut-off of ≥104.667 pg/mL, suitable for predicting candidemia with a sensitivity of 100%, specificity of 92% and area under ROC value of 0.958 (95% CI: 0.915-1; p < 0.001). A phylogenetic tree with three population groups, clade 1, 2 and 3, consisting of Candida auris (1), Candida tropicalis (2) and Candida parapsilosis (2), respectively, was generated. The diagnosis of candidemia based on mannan antigen detection gives early results and has high negative predictive values. It can be combined with other biomarkers to increase sensitivity, specificity and positive predictive value.

Rapid and sensitive detection of Candida mannan related to the immune system with a plasmonic sensor chip

To establish a rapid evaluation method for Candida mannan in the saliva, which is a marker molecule of immunity, we develop a fluorescent immunosensor enhanced with grating-coupled surface plasmon resonance using a plasmonic chip i.e., a metal-coated substrate with a wavelength-sized periodic structure. A two-dimensional hole-array chip with two kinds of pitches of 495 nm × 475 nm is used for fluorescence enhancement. The capture antibody is immobilized to the aminated chip surface via a crosslinker with succinimide at both ends, and a stable capture interface is constructed by covalent bonding. Finally, Candida mannan in the standard solution is measured up to 0.1 ng ml−1. Furthermore, in saliva samples, Candida mannan is quantitatively detected between 0.05 and 0.25 ng ml−1, and the highly sensitive detection with the Candida mannan assay system is indicated.

P399 Diagnostic value of Candida coloni zation index and serum Candida mannan antigen for candidemia in febrile episodes of pediatric lymphoreticular malignancies

Poster session 3, September 23, 2022, 12:30 PM - 1:30 PMObjective: To evaluate the diagnostic performance of Candida colonization index and serum Candida mannan antigen predicting candidemia in febrile episodes of pediatric lymphoreticular malignanciesMethodsIt was a prospective observational study done for 18 months, from November 2018 to April 2020 at the pediatric oncology unit of a multispecialty tertiary care center. Based on our patient load, duration of the proposed study, and available resources, a sample size of 49 (n = 49) was decided and 100 febrile episodes in children with lymphoreticular malignancy were studied. Children below 12 years, receiving chemotherapy for hematological malignancy having oral or axillary temperature ˃38.3°C for ˃1 h were included in this study. Children receiving the antifungal treatment in last 7 days were excluded from the study. Blood collected on day1 and day4 was cultured in BACTEC-9120. For colonization, swabs and samples were collected and cultured on SDA on day1, day4, and day8. All Candida isolates were subcultured on SDA and subjected to Gram's stain, germ tube test followed by Microscan identification. DNA sequencing followed by phylogenetic analysis was done for all the isolates of Candida recovered from blood. Antifungal susceptibility of yeast stains was done. Serum collected on day1 was used for C. mannan antigen detection using ELISA system.ResultsPrevalence of candidemia was 5%. Non-albicans Candida spp were isolated from blood cultures on day 4. Candida colonization decreased from day1 to day8. Colonization index (CI) day1 showed 80% sensitivity 98.9% specificity, and 98.9% negative predictive value. Significant colonization (CI ≥0.5) was seen in a larger proportion of cases that developed candidemia. There was a significant association of Candida colonization (CI ≥0.5) with occurrence of candidemia on day1 and day4. A total of 4 (80%) of candidemia episodes were positive for serum mannan antigen while 1 (20%) was negative. Mannan antigen was detected earlier with 80% sensitivity, 92.6% specificity, and 98.9% negative predictive value. All Candida isolates were sensitive to fluconazole, amphotericin-B, and caspofungin.Receiver operator characteristic curves for diagnostic performance of various parameters in predicting candidemia show the following trends:Best parameter in terms of AUROC is the CI (Day 1).Best parameters in terms of sensitivity are the CI (Day 1), CI (Day 4), and mannan antigen level.Best parameter in terms of specificity is the CI (Day 8).Best parameter in terms of positive predictive value is the CI (Day 1).Best parameters in terms of negative predictive value are the CI (Day 1), CI (Day 4), and mannan antigen level.Best parameters in terms of diagnostic accuracy are the CI (Day 1), CI (Day 8).ConclusionThe CI can predict candidemia but the threshold value needs to be explored in pediatric patients with lymphoreticular malignancies. Mannan antigen detection gives early results with a high negative predictive value.

Detection of Aspergillus spp. and Candida albicans antigenemia in a sample of Iraqi patients with severe COVID-19

Introduction: Since December 2019, coronavirus disease 2019 (COVID-19), which is caused by SARS-CoV-2, has spread locally in Wuhan, China, and later on, a worldwide outbreak occurred. Invasive fungal infections can cause complications in critically ill immunocompromised patients of COVID-19, especially those admitted to intensive care units and who required mechanical ventilation. Candida albicans have been the most common pathogenic species, followed by other Candida spp. Mannan is a major component of the Candida cell wall and can be detected by the enzyme-linked immunosorbent assay (ELISA) in blood and other fluids. Invasive pulmonary aspergillosis is considered a life-threatening infection, especially among immunocompromised patients. COVID-19-associated pulmonary aspergillosis has emerged as an important complication among patients in the intensive care units. Galactomannan (GM) is a major cell-wall component of Aspergillus spp. and can be found in body fluids. Blood GM can be detected by the enzyme immunoassay. The aim of the current study is to assess the frequency of aspergillosis and candidiasis among COVID-19 patients in some hospitals in Baghdad by using GM and mannan biomarkers. Methods: During the period from February 2020 to May 2021, 175 COVID-19 blood samples of patients were collected and a sandwich ELISA test was performed to detect GM Ag of Aspergillus spp. and mannan Ag of Candida spp. Results: Regarding C-reactive protein (CRP), significant differences were seen among Aspergillus/COVID-19 patients (p = 0.029). Regarding sex and age group, the results indicated that of a total of 175 adult patients with positive COVID-19, more than half of the patients were males. Regarding the distribution of mannan Ag and GM Ag in COVID-19 patients, it was seen that out of the 175 patients, 167 (95.43%) Candida mannan Ag were negative and only 8 (4.57%) were positive, and 170 (79.14%) Aspergillus GM Ag were negative and only 5 (2.86%) were positive. It was also seen that 2 patients (1.14%) who had both Candida mannan and Aspergillus GM were positive and 173 (98.6%) were negative. No statistically significant difference was seen in candidiasis and aspergillosis among patients with COVID-19 regarding age group, sex, underlying chronic diseases (hypertension and diabetes mellitus), and biochemical tests. Conclusion: COVID-19 infections increased with age and were seen more in males than in females. The percentage of infection with C. albicans and Aspergillus spp. among COVID-19 patients was not significant, and this may come from the random collection of samples from patients with different stages of illness. A significant correlation was found between Aspergillus GM Ag in COVID-19 patients and the CRP test.

Intensive Care Antifungal Stewardship Programme Based on T2Candida PCR and Candida Mannan Antigen: A Prospective Study.

Non-culture-based biomarkers may improve diagnosis and antifungal treatment (AFT) of invasive candidiasis (IC). We evaluated an antifungal stewardship programme (AFSP) in a prospective intensive care unit (ICU) study, which included T2Candida and Candida mannan antigen (MAg) screening of patients with sepsis and a high risk of IC. Patients with non-neutropenic sepsis and a high risk of IC from two large tertiary ICUs were prospectively included, during a one-year period. IC was classified as proven, likely, possible or unlikely. The AFSP, diagnostic values of T2Candida and MAg, and the consumption of antifungals were evaluated. An amount of 219 patients with 504 T2Candida/MAg samples were included. IC was classified as proven in 29 (13.2%), likely in 7 (3.2%) and possible in 10 (5.5%) patients. Sensitivity/specificity/PPV/NPV values, comparing proven/likely versus unlikely IC, were 47%/100%/94%/90% for BC alone, 50%/97%/75%/90% for T2Candida alone, and 39%/96%/67%/88% for MAg alone. For the combination of T2Candida/MAg taken ≤3 days after AFT initiation, sensitivity/specificity/PPV/NPV was 70%/90%/63%/93%. T2Candida/MAg contributed to early (<3 days) AFT initiation in 13%, early AFT discontinuation in 25% and abstaining from AFT in 24% of patients. No reduction in overall use of AFT during the study period compared with the previous year was observed. An AFSP based on T2Candida and MAg screening contributed to a reduction of unnecessary treatment, but not overall AFT use. The diagnostic performance of T2Candida was lower than previously reported, but increased if T2Candida was combined with MAg.

Glucan and glycogen exist as a covalently linked macromolecular complex in the cell wall of Candida albicans and other Candida species

The fungal cell wall serves as the interface between the organism and its environment. Complex carbohydrates are a major component of the Candida albicans cell wall, i.e., glucan, mannan and chitin. β-Glucan is a pathogen associated molecular pattern (PAMP) composed of β-(1 → 3,1 → 6)-linked glucopyranosyl repeat units. This PAMP plays a key role in fungal structural integrity and immune recognition. Glycogen is an α-(1 → 4,1 → 6)-linked glucan that is an intracellular energy storage carbohydrate. We observed that glycogen was co-extracted during the isolation of β-glucan from C. albicans SC5314. We hypothesized that glucan and glycogen may form a macromolecular species that links intracellular glycogen with cell wall β-(1 → 3,1 → 6)-glucan. To test this hypothesis, we examined glucan-glycogen extracts by multi-dimensional NMR to ascertain if glycogen and β-glucan were interconnected. 1H NMR analyses confirmed the presence of glycogen and β-glucan in the macromolecule. Diffusion Ordered SpectroscopY (DOSY) confirmed that the β-glucan and glycogen co-diffuse, which indicates a linkage between the two polymers. We determined that the linkage is not via peptides and/or small proteins. Our data indicate that glycogen is covalently linked to β-(1 → 3,1 → 6) glucan via the β -(1 → 6)-linked side chain. We also found that the glucan-glycogen complex was present in C. dublinensis, C. haemulonii and C. auris, but was not present in C. glabrata or C. albicans hyphal glucan. These data demonstrate that glucan and glycogen form a novel macromolecular complex in the cell wall of C. albicans and other Candida species. This new and unique structure expands our understanding of the cell wall in Candida species.

Reinvestigation of Carbohydrate Specificity of EBCA-1 Monoclonal Antibody Used for the Detection of Candida Mannan.

Monoclonal antibody EBCA-1 is used in the sandwich immune assay for the detection of circulating Candida mannan in blood sera samples for the diagnosis of invasive candidiasis. To reinvestigate carbohydrate specificity of EBCA-1, a panel of biotinylated oligosaccharides structurally related to distinct fragments of Candida mannan were loaded onto a streptavidin-coated plate to form a glycoarray. Its use demonstrated that EBCA-1 recognizes the trisaccharide β-Man-(1→2)-α-Man-(1→2)-α-Man and not homo-α-(1→2)-linked pentamannoside, as was reported previously.

An integrated approach to the diagnosis of bacterial and fungal bloodstream infections in cancer patients

Purpose of the study . To evaluate the diagnostic significance of accelerated and affordable verification of a bloodstream infection pathogen using biomarkers: procalcitonin and the Platelia ™ Candida Ag Plus mannan antigen. Patients and methods . 349 cancer patients with febrile fever were examined from 6 medical and diagnostic oncological hospitals in the Southern Federal District of the Russian Federation during 2019. Patients aged from 1 to 85 years were hospitalized in intensive care, pediatric oncology and hematology oncology departments. Patient informed consent for the study wasobtained. The diagnostic algorithm included: a blood test using an automatic BacT /ALERT 3D analyzer and a parallel study of the level of biomarkers with enzyme immunoassay. Identification of strains and determination of sensitivity to antimicrobial agents was determined on a Vitek 2 automatic analyzer (BioMerieux, France). Procalcitonin levels greater than 10 ng/ml were registered to determine the development of bacterial inflammation. Procalcitonin was determined with Procalcitonin — ELISA-BEST kits (Russia). Mannan antigen was determined using Platelia Candida Ag kits (France). The result was considered positive at the antigen concentration of ≥125 pg/ml. Candida mannan antigen allowed us to decide on the involvement of Candida spp. in the infectious process. Results. An integrated approach to the diagnosis of bloodstream infections increased the percentage of detection of pathogens up to 58.7%. Bacterial infection testing both with the blood culture method and the procalcitonin determination in blood serum revealed similar diagnostic values. Candida mannan antigen testing significantly improved the early diagnosis of Candidal infection, despite negative blood culture, which was probably associated with prolonged cultivation of Candida spp. in the blood (from 2 to 5 days). The inclusion of biomarker testing in the diagnostic algorithm in cases of suspected bloodstream infection allowed early pathogen identification and starting an adequate antibacterial or antifungal therapy. Conclusion. An integrated approach to the diagnosis of bloodstream infections improved and, just as importantly, significantly accelerated the pathogen verification. Bacterial infection cases showed comparable results of hemoculturing and biomarker testing; however, in case of candidal infection, determination of Candida mannan antigen appears critical, as it was significantly more sensitive than the result of blood culture and allowed to identify the etiology of fever of unknown origin in many patients.

Oral Candida Mannan Concentrations Correlate with Symptoms/Signs of Ill Health and the Immune Status.

A relationship has been proposed between increases in oral Candida concentrations and host immunity. Therefore, the present study was conducted to investigate the relationship between oral Candida mannan concentrations and symptoms/signs of ill health and the immune status and also to examine whether health/the immune status may be evaluated based on oral Candida mannan concentrations. The health conditions of 25 healthy individuals and 10 cancer patients receiving cytotoxic chemotherapy were assessed using a questionnaire and oral rinse solutions collected on consecutive days. Candida mannan concentrations in oral rinse solutions were measured using a commercial sandwich ELISA kit. The use of dentures was identified as a significant independent factor increasing Candida mannan concentrations. In a stratified analysis based on the use of dentures, significantly increased Candida mannan concentrations were detected in healthy volunteers with chills and in cancer patients with slight/moderate fever (37.5-38.4°C) (multivariate analysis, p < 0.01) who were non-denture users. These symptoms/signs may be associated with (pre-)infection, during which the immune system is activated and needs to function well. The present results suggest that oral Candida mannan concentrations are a predictive marker for health/the immune status.

Diagnostic value of Candida mannan antigen and anti-mannan IgG and IgM antibodies for Candida infection.

To assess the diagnostic value of serum Candida mannan antigen (MN) and anti-mannan IgG and IgM antibodies for candidiasis. This study was a prospective cohort study. Clinical data and venous blood samples from 23 medical centres in Beijing, China were collected between 1 January 2017 and 31 December 2018. All collected specimens were tested within one week for serum Candida MN and IgG and IgM antibodies using an ELISA kit. A total of 452 patients were enrolled, including 188 patients in the Candida exposure groups (56 patients with Candida bloodstream infection, 69 patients with Candida-positive tracheal aspirate cultures and 63 patients with Candida-positive urine cultures) and 264 patients in the control groups (212 healthy controls and 52 patients with bacteraemia). The receiver operating characteristic (ROC) curve of the 56 patients with Candida bloodstream infection and 212 healthy controls showed that serum MN and IgG had good diagnostic value. The area under the ROC curve (AUC) values were 0.812 (95% CI, 0.750-0.873) and 0.866 (95% CI, 0.808-0.924), respectively, wherein the MN specificity and sensitivity were 86.79% and 60.71%, and the IgG were 84.43% and 80.36%, respectively. The AUC of the combination of serum MN and IgG was 0.871(95% CI, 0.813-0.929), and the specificity and sensitivity were 93.87% and 57.14%. The serum levels of Candida MN and its IgG antibody have diagnostic value for Candida bloodstream infection, and combination of MN and IgG can improve diagnostic specificity and may provide a new approach for diagnosis of candidaemia.

Modification of Candida albicans cell wall by commensal gut bacteria

The human gut is populated with a vast community of microbes, the microbiota. Fungi comprise 0.1% of the total gut microbiota. Some of these fungi exist as benign members, however others such Candida albicans can undergo a pathogenic switch causing disease. The fungal cell wall is the first target for immune system recognition. Recent studies have suggested that Candida is decorated with different cell wall epitopes within different physiological niches, due to the impact of carbon source and oxygen availability on cell wall remodelling. Here we hypothesize that resident gut bacteria also play a major role in fungal cell wall remodelling and immune recognition. Data from our lab has shown that a common bacterium from the gut, Bacteroides thetaiotaomicron (Bt), produces an extensive repertoire of degradative enzymes to breakdown the Candida cell wall. Recently, we have identified novel enzymes in Bt from the glycoside hydrolase family 130 (GH130), which specifically target β1,2-linked mannan, a unique feature of Candida mannan. We have deleted multiple fungal mannan specific loci in Bt and examined the ability of deletion strains to utilise Candida mannan as a carbon source. These data suggest that Bt contains multiple pathways to degrade the Candida cell wall. Now we are systematically dissecting the impact of mannan degradation on the physiology of the fungus. This will provide insights into how two prominent members of the gut microbiota interact with each other, how the Candida cell wall is modified in the anaerobic environment of the gut, and the importance of this in promoting immune homeostasis.

Diagnostic Performance of T2Candida Among ICU Patients With Risk Factors for Invasive Candidiasis.

BackgroundInvasive candidiasis (IC) comprises candidemia and deep-seated candidiasis. Blood culture (BC) is the gold standard test, but sensitivity is low. T2Candida is a new diagnostic test. We investigated the performance of T2Candida, BC, and Candida mannan antigen (MAg) for detection of IC in a high-risk intensive care unit (ICU) population.MethodsOne-hundred twenty-six ICU patients at high risk of IC with sepsis despite 3 days of broad-spectrum antibiotics were included. Paired BC, T2Candida, and MAg were obtained twice weekly (334 sets). Patients were classified into proven, likely, possible, or unlikely IC based on patient record review.ResultsAt enrollment, 92 (77%) patients were receiving antifungal therapy (mainly fluconazole 66%). Fifteen (11.9%) patients were positive by BC (n = 4), T2Candida (n = 11), or MAg (n = 10). The T2Candida species distribution at inclusion (Candida albicans/Candida tropicalis: 8/11 [72.3%] and Candida glabrata/Candida krusei: 3/11 [27.3%]) was supported by the identification of BC or colonizing isolates in 10/11 cases. Patients were classified with proven (11), likely (6), possible (11), and unlikely (98) IC. Defining IC as proven/proven&likely/proven&likely&possible, respectively, the sensitivity was as follows: T2Candida (55%/59%/39%), BC (45%/29%/ 8%), and MAg (36%/41%/32%). The negative predictive value was similar across the tests for proven vs others and proven/likely vs others (94%–96% and 90%–95%, respectively). For test combinations including T2Candida, the sensitivity increased to 64%–65%, without hampering the positive predictive value.ConclusionsIn conclusion, although the diagnostic performance was modest for all the tests, the combination of T2Candida and BC seemed to have the best diagnostic performance, and thus implementation of T2Candida may improve the diagnosis of IC.

Relationship Between the Quantity of Oral Candida and Systemic Condition/Diseases of the Host: Oral Candida Increases with Advancing Age and Anemia.

The impact of host systemic conditions/diseases on the prosperity of oral Candida colonies remains unclear. The aim of the present study was to investigate whether a relationship exists between the quantity of oral Candida and the systemic condition/diseases of the host. The cross-sectional relationship between Candida mannan concentrations and health check-up results was analyzed in consideration of local conditions that influence the prevalence of oral Candida. Candida mannan concentrations correlated with age, the number of untreated decayed teeth, number of prosthetic teeth, salivary pH, HbA1c, and the red blood cell count in a univariate analysis. In a multivariate analysis, Candida mannan concentrations correlated with age, the number of untreated decayed teeth, number of prosthetic teeth, salivary pH, and the red blood cell count. Candida mannan concentrations were higher in subjects older than 80years, with a higher number of either untreated or prosthetic teeth, with a lower salivary pH, and with a decreased red blood cell count. Mannan concentrations were slightly higher in subjects with elevated HbA1c. The present results suggest a close relationship between the quantity of oral Candida and the systemic condition/diseases of the host. Oral Candida may increase in immunocompromised hosts.

Experimental Candida albicans osteomyelitis: Microbiologic, antigenic, histologic, and 18FDG-PET-CT imaging characteristics in a newly established rabbit model.

Candida osteomyelitis is a debilitating disease that is difficult to diagnose and treat. As there are no animal models or prospective studies for this uncommon infection, little is known about the pathogenesis, diagnosis, or treatment. We therefore sought to establish an animal model for the study of the pathophysiology, diagnostic modalities, and therapeutic interventions of Candida osteomyelitis. We developed a modified version of the Norden rabbit model of tibial osteomyelitis, in which the right tibia was inoculated intraoperatively with different inocula of C. albicans or normal saline as control. On days 7, 14, and 21 after inoculation, the animals underwent bone radiography, 18-fluoro-2-deoxy-D-glucose positron emission tomography combined with computed tomography (PET/CT) scan, and blood sampling for blood cultures, blood counts, erythrocyte sedimentation rate, and Candida mannan antigen serum levels. On day 21, animals were euthanized, and infected tibias harvested for culture and histology. Among eight evaluable animals inoculated with 1 × 106 to 1 × 107 cfu, histology and bone cultures established the presence of Candida osteomyelitis in seven, with a host response of neutrophils, mononuclear cells, multinucleate giant cells, fibrosis, and necrosis. Infected animals demonstrated radiological signs of osteomyelitis with significantly increased tracer uptake in 18FDG-PET/CT scans (P < .01) and elevated serum mannan levels (P < .01). All blood cultures were negative. Indices of inflammation were only slightly increased. In conclusion, we report successful establishment of a new animal model of Candida albicans osteomyelitis that may be applicable to advancing our understanding of the pathophysiology, diagnostic modalities, and treatment of this debilitating infection.

Binding of Elementary Bodies by the Opportunistic Fungal Pathogen Candida albicans or Soluble β-Glucan, Laminarin, Inhibits Chlamydia trachomatis Infectivity.

Microbial interactions represent an understudied facet of human health and disease. In this study, the interactions that occur between Chlamydia trachomatis and the opportunistic fungal pathogen, Candida albicans were investigated. Candida albicans is a common component of the oral and vaginal microbiota responsible for thrush and vaginal yeast infections. Normally, Candida exist in the body as yeast. However, disruptions to the microbiota create conditions that allow expanded growth of Candida, conversion to the hyphal form, and tissue invasion. Previous studies have shown that a myriad of outcomes can occur when Candida albicans interacts with pathogenic bacteria. To determine if C. trachomatis physically interacts with C. albicans, we incubated chlamydial elementary bodies (EB) in medium alone or with C. albicans yeast or hyphal forms for 1 h. Following incubation, the samples were formaldehyde-fixed and processed for immunofluorescence assays using anti-chlamydial MOMP or anti- chlamydial LPS antibodies. Replicate samples were replenished with culture medium and incubated at 35°C for 0–120 h prior to fixation for immunofluorescence analysis or collection for EB infectivity assays. Data from this study indicates that both C. trachomatis serovar E and C. muridarum EB bind to C. albicans yeast and hyphal forms. This interaction was not blocked by pre-incubation of EB with the Candida cell wall components, mannan or β-glucans, suggesting that EB interact with a Candida cell wall protein or other structure. Bound EB remained attached to C. albicans for a minimum of 5 days (120 h). Infectivity assays demonstrated that EB bound to C. albicans are infectious immediately following binding (0h). However, once bound to C. albicans, EB infectivity decreased at a faster rate than EB in medium alone. At 6h post binding, 40% of EB incubated in medium alone remained infectious compared to only 16% of EB bound to C. albicans. Likewise, pre-incubation of EB with laminarin, a soluble preparation of β-glucan, alone or in combination with other fungal cell wall components significantly decreases chlamydial infectivity in HeLa cells. These data indicate that interactions between EB and C. albicans inhibit chlamydial infectivity, possibly by physically blocking EB interactions with host cell receptors.

Cell wall mannan of Candida krusei mediates dendritic cell apoptosis and orchestrates Th17 polarization via TLR-2/MyD88-dependent pathway

Dendritic cells (DCs) abundantly express diverse receptors to recognize mannans in the outer surface of Candida cell wall, and these interactions dictate the host immune responses that determine disease outcomes. C. krusei prevalence in candidiasis worldwide has increased since this pathogen has developed multidrug resistance. However, little is known how the immune system responds to C. krusei. Particularly, the molecular mechanisms of the interplay between C. krusei mannan and DCs remain to be elucidated. We investigated how C. krusei mannan affected DC responses in comparison to C. albicans, C. tropicalis and C. glabrata mannan. Our results showed that only C. krusei mannan induced massive cytokine responses in DCs, and led to apoptosis. Although C. krusei mannan-activated DCs underwent apoptosis, they were still capable of initiating Th17 response. C. krusei mannan-mediated DC apoptosis was obligated to the TLR2 and MyD88 pathway. These pathways also controlled Th1/Th17 switching possibly by virtue of the production of the polarizing cytokines IL-12 and IL-6 by the C. krusei mannan activated-DCs. Our study suggests that TLR2 and MyD88 pathway in DCs are dominant for C. krusei mannan recognition, which differs from the previous reports showing a crucial role of C-type lectin receptors in Candida mannan sensing.

Differential dendritic cell responses to cell wall mannan of Candida albicans, Candida parapsilosis, and Candida dubliniensis.

Mannan (mannosylated glycoproteins) in the outermost layer of the Candida cell wall may be the first molecules that interact with host dendritic cells (DCs) and activate immune responses that determine disease outcomes. However, little is known about how different mannan structures of common oral Candida species affect DC activation. The effects of heat-inactivated (HI) yeast cells and soluble mannan of Candida albicans, Candida parapsilosis, and Candida dubliniensis on bone marrow-derived DC (BMDC) responses were compared. HI Candida and the mannan exhibited different effects on BMDC activation and functions, which could be due to other carbohydrate compositions in the yeast cell wall. Among Candida mannan, the C. albicans mannan was the weakest stimulus and induced only interferon (IFN)-γ production. This suggests the possibility that C. albicans mannan may skew T helper (Th) responses from protective Th17 toward Th1. In contrast, C. parapsilosis mannan caused strong BMDC activation and high production of several proinflammatory cytokines which possibly promote hyperinflammation. Meanwhile, C. dubliniensis mannan induced moderate BMDC responses, which may correlate with its lower pathogenicity. Therefore, mannan of each Candida species play distinct roles in DC responses and may be involved in the immunopathogenesis and disease severity of oral candidiasis as well as other Candida infection.

Role of Molecular Biomarkers in the Diagnosis of Invasive Fungal Diseases in Children.

Invasive fungal diseases are important clinical problems that are often complicated by severe illness and therefore the inability to use invasive measures to definitively diagnose the disease. Tests for a range of fungal biomarkers that do not require an invasive sample-collection procedure have been incorporated into adult clinical practice, but pediatric data and pediatric-specific recommendations for some of these diagnostic tools are lacking. In this review, we summarize the published literature and contemporary strategies for using the biomarkers galactomannan, (1→3)-β-d-glucan, Candida mannan antigen and anti-mannan antibody, and fungal polymerase chain reaction for diagnosing invasive fungal disease in children. Data on biomarker use in neonates and children with cancer, history of hematopoietic stem cell transplant, or primary immunodeficiency are included. Fungal biomarker tests performed on blood, other body fluids, or tissue specimens represent promising adjuncts to the diagnostic armamentarium in populations with a high prevalence of invasive fungal disease, but substantial gaps exist in the correct use and interpretation of these diagnostic tools in pediatric patients.

Contribution of Candida biomarkers and DNA detection for the diagnosis of invasive candidiasis in ICU patients with severe abdominal conditions.

BackgroundTo assess the performance of Candida albicans germ tube antibody (CAGTA), (1 → 3)-ß-D-glucan (BDG), mannan antigen (mannan-Ag), anti-mannan antibodies (mannan-Ab), and Candida DNA for diagnosing invasive candidiasis (IC) in ICU patients with severe abdominal conditions (SAC).MethodsA prospective study of 233 non-neutropenic patients with SAC on ICU admission and expected stay ≥ 7 days. CAGTA (cutoff positivity ≥ 1/160), BDG (≥80, 100 and 200 pg/mL), mannan-Ag (≥60 pg/mL), mannan-Ab (≥10 UA/mL) were measured twice a week, and Candida DNA only in patients treated with systemic antifungals. IC diagnosis required positivities of two biomarkers in a single sample or positivities of any biomarker in two consecutive samples. Patients were classified as neither colonized nor infected (n = 48), Candida spp. colonization (n = 154) (low-grade, n = 130; high-grade, n = 24), and IC (n = 31) (intra-abdominal candidiasis, n = 20; candidemia, n = 11).ResultsThe combination of CAGTA and BDG positivities in a single sample or at least one of the two biomarkers positive in two consecutive samples showed 90.3 % (95 % CI 74.2–98.0) sensitivity, 42.1 % (95 % CI 35.2–98.8) specificity, and 96.6 % (95 % CI 90.5–98.8) negative predictive value. BDG positivities in two consecutive samples had 76.7 % (95 % CI 57.7–90.1) sensitivity and 57.2 % (95 % CI 49.9–64.3) specificity. Mannan-Ag, mannan-Ab, and Candida DNA individually or combined showed a low discriminating capacity.ConclusionsPositive Candida albicans germ tube antibody and (1 → 3)-ß-D-glucan in a single blood sample or (1 → 3)-ß-D-glucan positivity in two consecutive blood samples allowed discriminating invasive candidiasis from Candida spp. colonization in critically ill patients with severe abdominal conditions. These findings may be helpful to tailor empirical antifungal therapy in this patient population.