Utility of incorporation of beta-D-glucan and T2Candida testing for diagnosis and treatment of candidemia

The additive role of non-culture-based methods for the diagnosis of candidemia remains unknown. We evaluated 2 clinical practices followed in our hospitals for the diagnosis of candidemia, namely practice#1 including a combination of blood cultures and T2Candida, and practice#2 that also included Beta-D-glucan (BDG). Three out of 96 patients testing positive with practice#1 received a complete antifungal course. Of the 120 patients evaluated with practice#2, 29 were positive. Only 55.2% of those received a complete course. We observed significant differences in antifungal utilization, with 268.5 antifungal days/1000 patient-days for practice#1, as opposed to 371.9 days for practice#2, a nearly 40% difference. However, we found similar rates of antifungal discontinuation among negative patients at 3 days of testing (36.8% and 37.0% respectively). No differences were detected in death and/or subsequent diagnosis of candidemia. In summary, addition of BDG was interpreted variably by clinicians, was associated with an increase in antifungal utilization, and did not correlate with measurable clinical benefits for patients.

Combination of serum and peritoneal 1.3-beta-D-glucan can rule out intra-abdominal candidiasis in surgical critically ill patients: a multicenter prospective study

BACKGROUND

Intra-abdominal candidiasis (IAC) is difficult to predict in critically ill patients with intra-abdominal infection, leading to the overuse of antifungal treatments. Serum and peritoneal 1.3-beta-D-glucan (sBDG and pBDG) have been proposed to confirm or invalidate the diagnosis of IAC, but clinical studies have reported inconsistent results, notably because of heterogeneous populations with a low IAC prevalence. This study aimed to identify a high-risk IAC population and evaluate pBDG and sBDG in diagnosing IAC.

METHODS

This prospective multicenter noninterventional French study included consecutive critically ill patients undergoing abdominal surgery for abdominal sepsis. The primary objective was to establish the IAC prevalence. The secondary objective was to explore whether sBDG and pBDG could be used to diagnose IAC. Wako® beta-glucan test (WT, Fujifilm Wako Chemicals Europe, Neuss, Germany) was used for pBDG measurements. WT and Fungitell® beta-D-glucan assay (FA, Associate of Cape Cod, East Falmouth, USA) were used for sBDG measurements.

RESULTS

Between 1 January 2020 and 31 December 2022, 199 patients were included. Patients were predominantly male (63%), with a median age of 66 [54-72] years. The IAC prevalence was 44% (87/199). The main IAC type was secondary peritonitis. Septic shock occurred in 63% of cases. After multivariate analysis, a nosocomial origin was associated with more IAC cases (P = 0.0399). The median pBDG level was significantly elevated in IAC (448 [107.5-1578.0] pg/ml) compared to non-IAC patients (133 [16.0-831.0] pg/ml), P = 0.0021. For a pBDG threshold of 45 pg/ml, the negative predictive value in assessing IAC was 82.3%. The median sBDG level with WT (n = 42) at day 1 was higher in IAC (5 [3.0-9.0] pg/ml) than in non-IAC patients (3 [3.0-3.0] pg/ml), P = 0.012. Similarly, median sBDG level with FA (n = 140) at day 1 was higher in IAC (104 [38.0-211.0] pg/ml) than in non-IAC patients (50 [23.0-141.0] pg/ml), P = 0.009. Combining a peritonitis score < 3, sBDG < 3.3 pg/ml (WT) and pBDG < 45 pg/ml (WT) yielded a negative predictive value of 100%.

CONCLUSION

In critically ill patients with intra-abdominal infection requiring surgery, the IAC prevalence was 44%. Combining low sBDG and pBDG with a low peritonitis score effectively excluded IAC and could limit unnecessary antifungal agent exposure.

TRIAL REGISTRATION

The study was registered with ClinicalTrials.gov (ID number 03997929, first registered on June 24, 2019).

Can Beta-D-Glucan testing as part of the diagnostic pathway for Invasive Fungal Infection reduce anti-fungal treatment costs?

We performed a cost comparison of the current diagnostic and treatment pathway for invasive fungal infection (IFI) versus a proposed pathway that incorporates Beta-D-Glucan (BDG) testing from the NHS perspective. A fungal pathogen was identified in 58/107 (54.2%) patients treated with systemic anti-fungals in the Critical Care Department. Mean therapy duration was 23 days (standard deviation [SD] = 22 days), and cost was £5590 (SD = £7410) per patient. Implementation of BDG tests in the diagnostic and treatment pathway of patients with suspected IFI could result in a mean saving of £1643 per patient should a result be returned within two days.

Candida Pneumonia: An Innocent Bystander or a Silent Killer?

Invasive candidiasis is predominantly seen in immunosuppressed patients and carries a significant mortality. The clinical spectrum of invasive candidiasis encompasses candidemia and disseminated infection (intra-abdominal abscess, osteomyelitis, endophthalmitis, and Candida meningitis). The existence of Candida pneumonia has been largely debated over the years due to its rarity and presence of frequent colonization. Demonstration of Candida species by lung biopsy along with evidence of inflammation is the only way to confirm this entity. The interpretation of Candida in respiratory specimens and the decision to initiate antifungal therapy is controversial due to the lack of clinical evidence. In this mini-review, we discuss the currently available clinical data from the literature on Candida pneumonia and future perspectives regarding the need for antifungal therapy in such patients.

Nocardiosis and elevated beta-d-glucan in solid organ transplant recipients

Beta-D-glucan (BDG) testing can expedite the diagnosis of invasive fungal infections in immunocompromised hosts. Elevated BDG levels have been reported in both in-vitro studies assessing cross-reactivity with Nocardia spp. and published cases of patients with nocardiosis, but there is little data on this association in solid organ transplantation (SOT) recipients. To explore this association, we conducted a case series of SOT recipients with culture-proven nocardiosis and BDG testing who received their care at our institution between 2016 and 2021. We found thirteen cases of nocardiosis in SOT recipients, of which three cases met our case definition of an elevated BDG. Their clinical courses are detailed in the present report. We found that BDG may be elevated in SOT with nocardiosis with no identified cause of false positive BDG, though a causal association cannot be determined. Future prospective studies that better evaluate the association between nocardiosis and BDG are warranted, as are studies that better characterize the possible variability in reactivity amongst Nocardia spp.

Comparison of two β-D-glucan assays for detecting invasive fungal diseases in immunocompromised patients

(1-3)-β-D-glucan (BDG) is a major biomarker of invasive fungal diseases (IFDs), which are life-threatening for immunodeficient patients. We compared the clinical performance of two BDG-detection assays. The precision, linearity, reference interval, and limit of quantitation of the Wako BDG assay were analyzed and the performance was compared with that of the Goldstream BDG assay using 272 clinical serum samples. The repeatability, within-laboratory imprecision, and limit of quantitation of the Wako BDG assay were 3.8%, 5.9%, and 7.35 pg/mL, respectively (linearity, 23.8-557 pg/mL; R² = 0.998). The correlation coefficient, slope, and y-intercept for the Wako BDG assay versus Goldstream BDG assay were 0.29, 3.82, and 0.04, respectively. The sensitivity and specificity were 43.8% and 94.9% for the Wako BDG assay and 39.6% and 83.5% for the Goldstream BDG assay, respectively. In clinical settings, the Wako BDG assay is suitable for diagnosing patients with IFDs.

Immunomodulation Through Beta-D-glucan in Chemically-induced Necrotizing Pancreatitis

BACKGROUND

Although the ability of β-D-glucan and monophosphoryl lipid A (MPLA) to modulate immune responses has been studied in human primary cells, their effect on sterile inflammation models such as necrotizing pancreatitis has never been investigated.

MATERIALS AND METHODS

85 male New Zealand rabbits were assigned into following groups: A: control, B: pretreatment with β-D-glucan 3 d before pancreatitis, C: pretreatment with MPLA 3 d before pancreatitis, D: pretreatment with β-D-glucan and laminarin 3 d before pancreatitis, E: treatment with β-D-glucan 1 d after pancreatitis, and F: MPLA 1 d after pancreatitis. Pancreatitis was induced by sodium taurocholate injection into the pancreatic duct and parenchyma. Survival was recorded for 21 d. On days 1, 3, and 7, blood was collected for amylase measurement. Peripheral blood mononuclear cells were isolated and stimulated for tumor necrosis factor alpha and interleukin 10 production. Pancreatic necrosis and tissue bacterial load were assessed.

RESULTS

21-d survival was prolonged after pretreatment or treatment with β-D-glucan; this benefit was lost with laminarin administration. At sacrifice, pancreatic inflammatory alterations were more prominent in the control group. Bacterial load was lower after pretreatment or treatment with β-D-glucan and MPLA. Tumor necrosis factor alpha production from stimulated peripheral blood mononuclear cells was significantly decreased, whereas interleukin 10 production remained unaltered after pretreatment or treatment with β-D- glucan.

CONCLUSIONS

β-D-glucan reduces mortality of experimental pancreatitis in vivo. This is mediated through attenuation of cytokine production and prevention of bacterial translocation.

Performance of the (1,3)-Beta-D-Glucan Assay on Bronchoalveolar Lavage Fluid for the Diagnosis of Invasive Pulmonary Aspergillosis

Detection of (1,3)-beta-D-glucan (BDG), a component of the cell wall of many fungi, was studied in bronchoalveolar lavage fluid (BALF) as a possible aid for the diagnosis of proven/probable invasive pulmonary aspergillosis (IPA). BDG was measured on stored BALF from 13 patients with EORTC/MSGERC defined proven/probable IPA and 26 matched control patients without IPA. The median BALF BDG was 80 pg/mL (range < 45-8240 pg/mL) in the IPA cohort and 148 pg/mL (range < 45-5460 pg/mL) in the non-IPA cohort. Using a positive cutoff of ≥ 80 pg/mL, sensitivity was 54% and specificity was 38%. Higher cutoff values led to improvement in specificity but a dramatic decrease in sensitivity. ROC/AUC analysis was unable to identify an optimal cutoff value at which test performance was enhanced: AUC 0.43, 95% CI 0.24-0.63. When the BDG assay was performed on BALF, neither sensitivity nor specificity was sufficient for use in the diagnosis of IPA.

Evaluation of biomarkers: Galactomannan and 1,3-beta-D-glucan assay for the diagnosis of invasive fungal infections in immunocompromised patients from a tertiary care centre

Purpose

Due to limitations of traditional microbiological techniques, standardised fungal biomarker tests such as Galactomannan Index (GMI) and 1,3-beta-D-glucan (BDG) are being preferred for diagnosis of invasive fungal infections (IFIs). These tests have been extensively used in developed countries but seldom in developing countries. The present study was performed to evaluate these tests for the diagnosis of IFIs in immunocompromised patients at an Indian tertiary care centre.

Materials and Methods

A retrospective hospital-based study was done in immunocompromised patients with clinical suspicion of IFI. The demographic, clinical, radiological and mycological details of the patients were recorded. The patients were categorised into proven, probable and no IFI (as per European Organization for Research and Treatment of Cancer/Mycoses Study Group criteria). The sensitivity and specificity of BDG Fungitell and Platelia Aspergillus antigen assays was estimated.

Results

A total of 70 consecutive patients were included, of which 41 had IFI (10 proven and 31 probable) while 29 had no IFI. A significant association was found between IFI and the presence of a central venous line (P = 0.035) and history of intake of T-cell immunosuppressants (P = 0.001). Median BDG values (pg/ml) in patients with proven IFI, probable IFI and no IFI were 300 (range: 70-500), 165 (range: 53-500) and 45 (range: 31-500), respectively. The receiver operating characteristic (ROC) curve analysis for BDG revealed an area under the curve of 0.995, sensitivity: 97.4% and specificity: 96.6% for IFI diagnosis. The ROC curve analysis of GMI revealed an AUC of 0.75 and 90% patients with invasive aspergillosis (IA) had positive GMI.

Conclusion

BDG has good sensitivity and specificity for distinguishing IFI from no IFIs and GMI may be used for diagnosing IA.

Serological biomarkers of candidemia: a retrospective evaluation of three assays

PURPOSE

Serologic testing allows for rapid detection of candidemia. More data are needed for the Virion\Serion ELISA antigen test (Ag), Hemkit Candida IHA antibody test (Ab), and Wako β-1,3-D-glucan assay (BDG).

METHODS

Tests were performed on serum samples from 120 cases of culture-confirmed candidemia and 44 Candida-negative controls. Sensitivities and specificities of individual tests as well as combinations were assessed.

RESULTS

The overall sensitivity of Ag, Ab, and Ag/Ab testing was 30, 40, and 54%, respectively, while in transplant patients it significantly dropped to 16, 26, and 40% (p = 0.02). For BDG testing it was 67%, both overall and in transplant patients. Especially Ag testing performed poorly among women ≤ 65 years with a significantly reduced sensitivity of 9% (p < 0.002). While the sensitivity of Ag/Ab testing was somewhat higher at 67% for C. albicans, it was significantly lower for non-albicans species at 42% (p = 0.006). The sensitivity of BDG testing for C. albicans and non-albicans species was not significantly different at 64 and 69%, respectively. Both Ag/Ab and BDG testing had a high specificity of 93%, for Ag testing it was 100%. Similar sensitivities were calculated for sera sampled on the day of and 4-6 days before sampling of positive blood cultures.

CONCLUSIONS

Serological markers are valuable tools for the early diagnosis of candidemia. Ab, Ag, and BDG testing are all characterized by high specificity. The Wako BDG test is significantly more sensitive compared to combined Candida-Ag/Ab testing, particularly in the setting of non-albicans species and specific host factors.

Elevated Serum Beta-D-Glucan with Pseudomonas, Aspergillus, and a Partially Acid-Fast Organism in Respiratory Cultures: A Case of Hickam's Dictum Over Occam's Razor

We describe a case of a man with ectopic Cushing's syndrome, elevated serum beta-D-glucan, and respiratory cultures with Pseudomonas, Aspergillus, and a partially acid-fast organism. Our case highlights challenges in diagnosis and management of coinfection in an immunocompromised host.

A Review of Diagnostic Methods for Invasive Fungal Diseases: Challenges and Perspectives

Invasive fungal diseases are associated with a high morbidity and mortality, particularly in the context of immunosuppression. Diagnosis of invasive fungal diseases is usually complicated by factors such as poor clinical suspicion and unspecific clinical findings. Access to modern diagnostic tools is frequently limited in developing countries. Here, we describe five real-life clinical cases from a Brazilian tertiary hospital, in order to illustrate how to best select diagnostic tests in patients with different fungal infections.

Intensive care medicine research agenda on invasive fungal infection in critically ill patients

PURPOSE

To describe concisely the current standards of care, major recent advances, common beliefs that have been contradicted by recent trials, areas of uncertainty, and clinical studies that need to be performed over the next decade and their expected outcomes with regard to Candida and Aspergillus infections in non-neutropenic patients in the ICU setting.

METHODS

A systematic review of the medical literature taking account of national and international guidelines and expert opinion.

RESULTS

Severe invasive fungal infections (IFIs) are becoming increasingly frequent in critically ill patients. Approximately 80% of IFIs are due to Candida spp. and 0.3-19% to Aspergillus spp. Recent observations emphasize the necessity of building a worldwide sentinel network to monitor the emergence of new fungal species and changes in susceptibility. Robust data on the attributable mortality are essential for the design of clinical studies with mortality endpoints. Although early antifungal therapy for Candida has been recommended in patients with risk factors, sepsis of unknown cause, and positive Candida serum biomarkers [β-1 → 3-D-glucan (BDG) and Candida albicans germ tube antibody (CAGTA)], its usefulness and influence on outcome need to be confirmed. Future studies may specifically address the optimal diagnostic and therapeutic strategies for patients with abdominal candidiasis. Better knowledge of the pharmacokinetics of antifungal molecules and tissue penetration is a key issue for intensivists. Regarding invasive aspergillosis, further investigation is needed to determine its incidence in the ICU, its relationship with influenza outbreaks, the clinical impact of rapid diagnosis, and the significance of combination treatment.

CONCLUSIONS

Fundamental questions regarding IFI have to be addressed over the next decade. The clinical studies described in this research agenda should provide a template and set priorities for the clinical investigations that need to be performed.

β-D-Glucan Assay in Diagnosis and Monitoring the Systemic Candidiasis in a Rat Model

BACKGROUND

Determination of β-D-Glucan (BDG) in the serum aids to diagnose the invasive fungal infections. The current study evaluated the diagnostic potential value of BDG assay in monitoring the disease in experimental systemic candidiasis in a rat model. The results can provide a useful preliminary data to improve this approach in developing countries.

OBJECTIVES

The present study aimed to evaluate β-D-Glucan assay in diagnosis and monitoring the systemic candidiasis in a rat model.

MATERIALS AND METHODS

Twenty one rats were infected with 10(6) Candida albicans blastospore per rat. Twelve rats were considered as the negative controls (six immunocompromised rats without infection and six intact rats). During a week, every 24 hours the BDG sera level was determined by both Fungitell and Wako kits. To confirm the systemic infection in each rat, the suspensions of their internal organs were cultivated on agar plates and the number of colony forming units (CFU) of C. albicans was counted.

RESULTS

All the infected rats were positive with BDG tests. An increasing level of BDG was observed during early days after injection. The cutoff value for discrimination of BDG positive sera was obtained from the negative sera by the Fungitell kit. The sensitivity, specificity, positive and negative predictive values assessed for the Fungitell kit were 95%, 66.6%, 90.47% and 80%, respectively. These criteria for those of Wako were 90%, 83.3%, 94.7% and 71.4%, respectively.

CONCLUSIONS

While BDG assay seems to be a sensitive and specific adjunctive tool to diagnose and monitor the experimental systemic candidiasis, it seems that measuring the positive cutoff value in different laboratory conditions is necessary for favorable establishment of these tests.

The utility of bronchoalveolar lavage beta-D-glucan testing for the diagnosis of invasive fungal infections

OBJECTIVES

To investigate the utility of beta-D-glucan (BDG) testing in bronchoalveolar lavage (BAL) fluid for the diagnosis of invasive fungal infection (IFI), as compared to BAL galactomannan (GM).

METHODS

We retrospectively reviewed medical records of 132 consecutive patients at the National Institutes of Health (NIH) in whom BAL BDG testing was performed for diagnosis of pneumonia. Using the European Organization for Research and Treatment of Cancer/Mycoses Study Group guidelines, we determined which patients had proven or probable IFI, and assessed the diagnostic performance of BAL BDG testing, relative to BAL GM. We also determined the reproducibility of the BDG assay in BAL via repeat testing of patient samples.

RESULTS

Ten patients had Pneumocystis pneumonia, and 34 patients had proven/probable IFI, including 14 with invasive aspergillosis (IA). BAL BDG was 100% sensitive for Pneumocystis. Although BAL BDG had similar sensitivity to BAL GM for the diagnosis of IA and IFI, it exhibited inferior specificity. Repeat testing demonstrated poor reproducibility of the BDG assay in BAL but not in serum.

CONCLUSIONS

BDG testing exhibits poor specificity and reproducibility in BAL. Identification of the BAL-specific factors that may interfere with the performance of the assay could improve the clinical usefulness of BAL BDG testing.