Diagnosis of Breakthrough Fungal Infections in the Clinical Mycology Laboratory: An ECMM Consensus Statement

The performance of bronchoalveolar lavage Aspergillus PCR testing in solid organ transplant recipients with invasive pulmonary aspergillosis

BACKGROUND

Invasive aspergillosis affects solid organ transplant (SOT) recipients, carrying a high risk of mortality and morbidity in this population. Rapid and accurate diagnosis is essential to ensure the initiation of correct antifungal therapy. We aimed to evaluate the performance of the bronchoalveolar lavage (BAL) Eurofins Viracor Aspergillus PCR (AspPCR) in diagnosing invasive pulmonary aspergillosis (IPA) in SOT recipients.

METHODS

We conducted a multicenter retrospective study of SOT recipients in Arizona from February 2019 to December 2022 who had AspPCR done at the time of the clinical encounter. Probable IPA was defined as a positive BAL culture with Aspergillus spp. with clinical and imaging findings of IPA per EORTC/MSGERC criteria.

RESULTS

Ninety-nine SOT recipients with 131 encounters with BAL AspPCR testing were included. The median age was 66, the majority were White, non-Hispanics (60%), and males (66%). Among the participants, 93 lung transplant recipients with 87 of the encounters received antifungal prophylaxis active against Aspergillus spp. Sixty-four encounters had BAL galactomannan (GM), all of which had BAL GM <1 OD, and one case had a serum GM of 10 OD. Nine cases met the definition of IPA. The sensitivity of the BAL AspPCR was 67% (95% CI 30%-93%), and the specificity was 98% (95% CI 93%-99%).

CONCLUSION

BAL AspPCR had moderate sensitivity and high specificity in identifying IPA in our cohort of SOT recipients. Further studies in populations with a higher prevalence of IPA are needed to evaluate the performance of this test.

Epidemiology of Invasive Candidiasis

Invasive candidiasis (IC) is an increasingly prevalent, costly, and potentially fatal infection brought on by the opportunistic yeast, Candida. Previously, IC has predominantly been caused by C. albicans which is often drug susceptible. There has been a global trend towards decreasing rates of infection secondary to C. albicans and a rise in non-albicans species with a corresponding increase in drug resistance creating treatment challenges. With advances in management of malignancies, there has also been an increase in the population at risk from IC along with a corresponding increase in incidence of breakthrough IC infections. Additionally, the emergence of C. auris creates many challenges in management and prevention due to drug resistance and the organism's ability to transmit rapidly in the healthcare setting. While the development of novel antifungals is encouraging for future management, understanding the changing epidemiology of IC is a vital step in future management and prevention.

A high-speed microscopy system based on deep learning to detect yeast-like fungi cells in blood

Background: Blood-invasive fungal infections can cause the death of patients, while diagnosis of fungal infections is challenging. Methods: A high-speed microscopy detection system was constructed that included a microfluidic system, a microscope connected to a high-speed camera and a deep learning analysis section. Results: For training data, the sensitivity and specificity of the convolutional neural network model were 93.5% (92.7-94.2%) and 99.5% (99.1-99.5%), respectively. For validating data, the sensitivity and specificity were 81.3% (80.0-82.5%) and 99.4% (99.2-99.6%), respectively. Cryptococcal cells were found in 22.07% of blood samples. Conclusion: This high-speed microscopy system can analyze fungal pathogens in blood samples rapidly with high sensitivity and specificity and can help dramatically accelerate the diagnosis of fungal infectious diseases.

Acute Invasive Pulmonary Aspergillosis: Clinical Presentation and Treatment

Among all clinical manifestations of pulmonary aspergillosis, invasive pulmonary aspergillosis (IPA) is the most acute presentation. IPA is caused by Aspergillus hyphae invading the pulmonary tissue, causing either tracheobronchitis and/or bronchopneumonia. The degree of fungal invasion into the respiratory tissue can be seen as a spectrum, going from colonization to deep tissue penetration with angio-invasion, and largely depends on the host's immune status. Patients with prolonged, severe neutropenia and patients with graft-versus-host disease are at particularly high risk. However, IPA also occurs in other groups of immunocompromised and nonimmunocompromised patients, like solid organ transplant recipients or critically ill patients with severe viral disease. While a diagnosis of proven IPA is challenging and often warranted by safety and feasibility, physicians must rely on a combination of clinical, radiological, and mycological features to assess the likelihood for the presence of IPA. Triazoles are the first-choice regimen, and the choice of the drug should be made on an individual basis. Adjunctive therapy such as immunomodulatory treatment should also be taken into account. Despite an improving and evolving diagnostic and therapeutic armamentarium, the burden and mortality of IPA still remains high. This review aims to give a comprehensive and didactic overview of the current knowledge and best practices regarding the epidemiology, clinical presentation, diagnosis, and treatment of acute IPA.

A Retrospective Observational Study on the Comparison of Different Diagnostic Modalities of Post-COVID Mucormycosis

Background Mucormycosis, attributed to a group of molds known as mucormycosis, is a rare yet life-threatening fungal infection often colloquially referred to as black fungus. While its incidence notably surged during the second wave of COVID-19 infections in India, it's essential to recognize that mucormycosis was a significant concern even before the advent of the pandemic. Understanding the prevalence and characteristics of this infection in the pre-COVID era provides a crucial context for evaluating its impact and dynamics during the pandemic. Multiple diagnostic methods, such as potassium hydroxide (KOH) mount, culture, matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and histopathological examination (HPE), are available for identifying this lethal infection. The primary objective of this study is to ascertain the sensitivity of various diagnostic methods for mucormycosis and to analyze the comparative effectiveness of microbiological versus histopathological diagnoses. Methods We conducted a retrospective observational study spanning six months, from May 2021 to October 2021, encompassing all mucormycosis cases meeting the inclusion criteria and diagnosed via histopathological examination (HPE) in the departments of pathology and microbiology. Microbiological tests were performed prior to the histopathological examinations. Sensitivity was assessed through statistical analysis, and the relationship between microbiological and histopathological diagnoses was evaluated using the chi-square test. Results Biopsy samples of 77 patients were collected, comprising 56 male and 21 female patients. Regarding age distribution, most patients fell within the 41-60 age bracket, while the smallest proportion was over 60 years old. The sensitivity and specificity of histopathological diagnosis, confirmed with periodic acid-Schiff (PAS) and Grocott-Gomori's methenamine silver (GMS) staining, both recorded a flawless 100%. KOH mount sensitivity stood at 88.3%, while fungal culture and MALDI-TOF exhibited sensitivities of 75.3%. Histopathological analysis revealed that 17% of cases displayed minimal fungal hyphae alongside necrotic tissue, whereas 58% exhibited abundant fungal hyphae accompanied by inflammatory cells. Additionally, absolute neutrophilia was observed in 55% of cases. Conclusions In our study, histopathology and KOH mount emerged as not only compassionate but also cost-effective diagnostic tools for identifying mucormycosis. The economic aspect of these diagnostic methods is highlighted in the results section to provide a comprehensive understanding of their cost-effectiveness. Additionally, we utilized MALDI-TOF MS as a straightforward, economically viable, and expeditious method specifically for confirming the fungal subtype in mucormycosis cases. The rationale behind choosing either MALDI-TOF MS or KOH for the diagnosis is elucidated, contributing to a clearer interpretation of our diagnostic approach. Furthermore, our findings indicate that absolute neutrophilia consistently manifests in 55% of mucormycosis cases.

Fungal Endocarditis: Pathophysiology, Epidemiology, Clinical Presentation, Diagnosis, and Management

Fungal endocarditis accounts for 1% to 3% of all infective endocarditis cases, is associated with high morbidity and mortality (>70%), and presents numerous challenges during clinical care. Candida spp. are the most common causes of fungal endocarditis, implicated in over 50% of cases, followed by Aspergillus and Histoplasma spp. Important risk factors for fungal endocarditis include prosthetic valves, prior heart surgery, and injection drug use. The signs and symptoms of fungal endocarditis are nonspecific, and a high degree of clinical suspicion coupled with the judicious use of diagnostic tests is required for diagnosis. In addition to microbiological diagnostics (e.g., blood culture for Candida spp. or galactomannan testing and PCR for Aspergillus spp.), echocardiography remains critical for evaluation of potential infective endocarditis, although radionuclide imaging modalities such as 18F-fluorodeoxyglucose positron emission tomography/computed tomography are increasingly being used. A multimodal treatment approach is necessary: surgery is usually required and should be accompanied by long-term systemic antifungal therapy, such as echinocandin therapy for Candida endocarditis or voriconazole therapy for Aspergillus endocarditis.

Recent advances in antifungal drug development targeting lanosterol 14α-demethylase (CYP51): A comprehensive review with structural and molecular insights

Fungal infections are posing serious threat to healthcare system due to emerging resistance among available antifungal agents. Among available antifungal agents in clinical practice, azoles (diazole, 1,2,4-triazole and tetrazole) remained most effective and widely prescribed antifungal agents. Now their associated side effects and emerging resistance pattern raised a need of new and potent antifungal agents. Lanosterol 14α-demethylase (CYP51) is responsible for the oxidative removal of 14α-methyl group of sterol precursors lanosterol and 24(28)-methylene-24,25-dihydrolanosterol in ergosterol biosynthesis hence an essential component of fungal life cycle and prominent target for antifungal drug development. This review will shed light on various azole- as well as non-azoles-based derivatives as potential antifungal agents that target fungal CYP51. Review will provide deep insight about structure activity relationship, pharmacological outcomes, and interactions of derivatives with CYP51 at molecular level. It will help medicinal chemists working on antifungal development in designing more rational, potent, and safer antifungal agents by targeting fungal CYP51 for tackling emerging antifungal drug resistance.

Establishment of a risk classifier to predict the in-hospital death risk of nosocomial fungal infections in cancer patients

BACKGROUND

Patients with malignancy are at a higher risk of developing nosocomial infections. However, limited studies investigated the clinical features and prognostic factors of nosocomial infections due to fungi in cancer patients. Herein, this study aims to investigate the clinical characteristics of in-hospital fungal infections and develop a nomogram to predict the risk of in-hospital death during fungal infection of hospitalized cancer patients.

METHODS

This retrospective observational study enrolled cancer patients who experienced in-hospital fungal infections between September 2013 and September 2021. Univariate and multivariate logistic regression analyses were performed to identify independent predictors of in-hospital mortality. Variables demonstrating significant statistical differences in the multivariate analysis were utilized to construct a nomogram for personalized prediction of in-hospital death risk associated with nosocomial fungal infections. The predictive performance of the nomogram was evaluated using receiver operating characteristic (ROC) curves, calibration curves, and decision curve analysis.

RESULTS

A total of 216 participants were included in the study, of which 57 experienced in-hospital death. C.albicans was identified as the most prevalent fungal species (68.0%). Respiratory infection accounted for the highest proportion of fungal infections (59.0%), followed by intra-abdominal infection (8.8%). The multivariate regression analysis revealed that Eastern Cooperative Oncology Group Performance Status (ECOG-PS) 3-4 (odds ratio [OR] = 6.08, 95% confidence interval [CI]: 2.04-18.12), pulmonary metastases (OR = 2.76, 95%CI: 1.11-6.85), thrombocytopenia (OR = 2.58, 95%CI: 1.21-5.47), hypoalbuminemia (OR = 2.44, 95%CI: 1.22-4.90), and mechanical ventilation (OR = 2.64, 95%CI: 1.03-6.73) were independent risk factors of in-hospital death. A nomogram based on the identified risk factors was developed to predict the individual probability of in-hospital mortality. The nomogram demonstrated satisfactory performance in terms of classification ability (area under the curve [AUC]: 0.759), calibration ability, and net clinical benefit.

CONCLUSIONS

Fungi-related nosocomial infections are prevalent among cancer patients and are associated with poor prognosis. The constructed nomogram provides an invaluable tool for oncologists, enabling them to make timely and informed clinical decisions that offer substantial net clinical benefit to patients.

Salvage Treatment for Invasive Aspergillosis and Mucormycosis: Challenges, Recommendations and Future Considerations

Invasive mold diseases are devastating systemic infections which demand meticulous care in selection, dosing, and therapy monitoring of antifungal drugs. Various circumstances regarding PK/PD properties of the applied drug, resistance/tolerance of the causative pathogen or host intolerability can lead to failure of the initial antifungal therapy. This necessitates treatment adaption in the sense of switching antifungal drug class or potentially adding another drug for a combination therapy approach. In the current state of drastically limited options of antifungal drug classes adaption of therapy remains challenging. Current guidelines provide restricted recommendations only and emphasize individual approaches. However, novel antifungals, incorporating innovative mechanisms of action, show promising results in late stage clinical development. These will expand options for salvage therapy in the future potentially as monotherapy or in combination with conventional or other novel antifungals. We outline current recommendations for salvage therapy including PK/PD considerations as well as elucidate possible future treatment options for invasive aspergillosis and mucormycosis.

Survival Outcome of Empirical Antifungal Therapy and the Value of Early Initiation: A Review of the Last Decade

AIM

This rapid systematic review aimed to collect the evidence published over the last decade on the effect of empirical antifungal therapy and its early initiation on survival rates.

METHODS

A systematic search was conducted in PubMed, Cochrane, Medline, Scopus, and Embase, in addition to a hand search and experts' suggestions.

RESULTS

Fourteen cohort studies and two randomized clinical trials reporting the survival outcome of empirical antifungal therapy were included in this review. Two studies reported the association between early empirical antifungal therapy (EAFT) and survival rates in a hematological cancer setting, and fourteen studies reported the outcome in patients in intensive care units (ICU). Six studies reported that appropriate EAFT decreases hospital mortality significantly; ten studies could not demonstrate a statistically significant association with mortality rates.

DISCUSSION

The inconsistency of the results in the literature can be attributed to the studies' small sample size and their heterogeneity. Many patients who may potentially benefit from such strategies were excluded from these studies.

CONCLUSION

While EAFT is practiced in many settings, current evidence is conflicting, and high-quality studies are needed to demonstrate the true value of this approach. Meanwhile, insights from experts in the field can help guide clinicians to initiate EAFT when indicated.

Application Value of Metagenomics Next-Generation Sequencing (mNGS) in Detection of Mucormycosis after Chemotherapy in Childhood Acute Leukemia

Objective

To analyze the application of macrogenomics next-generation sequencing (mNGS) in the detection of postchemotherapy trichomoniasis cases in children with acute leukemia.

Methods

To retrospectively analyze the clinical data of 7 patients with acute leukemia combined with trichomoniasis after chemotherapy in the department of hematology and oncology of Hebei Children's Hospital, and to summarize the characteristics of their postchemotherapy clinical data, diagnostic and therapeutic processes, and outcomes.

Results

Among the 7 children, 6 cases had acute lymphoblastic leukemia and 1 case had acute myeloid leukemia. mNGS detected trichoderma infection, including 1 case of pulmonary cerebral type and 6 cases of pulmonary type. After treatment, 1 case died, 2 cases were cured, and 4 cases improved.

Conclusion

The clinical manifestations of trichomoniasis after combined chemotherapy in pediatric acute leukemia lack specificity. Early application of the mNGS assay is of great value.

Monoclonal Antibodies and Invasive Aspergillosis: Diagnostic and Therapeutic Perspectives

Invasive aspergillosis (IA) is a life-threatening fungal disease that causes high morbidity and mortality in immunosuppressed patients. Early and accurate diagnosis and treatment of IA remain challenging. Given the broad range of non-specific clinical symptoms and the shortcomings of current diagnostic techniques, most patients are either diagnosed as “possible” or “probable” cases but not “proven”. Moreover, because of the lack of sensitive and specific tests, many high-risk patients receive an empirical therapy or a prolonged treatment of high-priced antifungal agents, leading to unnecessary adverse effects and a high risk of drug resistance. More precise diagnostic techniques alongside a targeted antifungal treatment are fundamental requirements for reducing the morbidity and mortality of IA. Monoclonal antibodies (mAbs) with high specificity in targeting the corresponding antigen(s) may have the potential to improve diagnostic tests and form the basis for novel IA treatments. This review summarizes the up-to-date application of mAb-based approaches in assisting IA diagnosis and therapy.

Fungal infections diagnosis - Past, present and future

Despite the scientific advances observed in the recent decades and the emergence of new methodologies, the diagnosis of systemic fungal infections persists as a problematic issue. Fungal cultivation, the standard method that allows a proven diagnosis, has numerous disadvantages, as low sensitivity (only 50% of the patients present positive fungal cultures), and long growth time. These are factors that delay the patient's treatment and, consequently, lead to higher hospital costs. To improve the accuracy and quickness of fungal infections diagnosis, several new methodologies attempt to be implemented in clinical microbiology laboratories. Most of these innovative methods are independent of pathogen isolation, which means that the diagnosis goes from being considered proven to probable. In spite of the advantage of being culture-independent, the majority of the methods lack standardization. PCR-based methods are becoming more and more commonly used, which has earned them an important place in hospital laboratories. This can be perceived now, as PCR-based methodologies have proved to be an essential tool fighting against the COVID-19 pandemic. This review aims to go through the main steps of the diagnosis for systemic fungal infection, from diagnostic classifications, through methodologies considered as "gold standard", to the molecular methods currently used, and finally mentioning some of the more futuristic approaches.

The Antifungal Pipeline: Fosmanogepix, Ibrexafungerp, Olorofim, Opelconazole, and Rezafungin

The epidemiology of invasive fungal infections is changing, with new populations at risk and the emergence of resistance caused by the selective pressure from increased usage of antifungal agents in prophylaxis, empiric therapy, and agriculture. Limited antifungal therapeutic options are further challenged by drug-drug interactions, toxicity, and constraints in administration routes. Despite the need for more antifungal drug options, no new classes of antifungal drugs have become available over the last 2 decades, and only one single new agent from a known antifungal class has been approved in the last decade. Nevertheless, there is hope on the horizon, with a number of new antifungal classes in late-stage clinical development. In this review, we describe the mechanisms of drug resistance employed by fungi and extensively discuss the most promising drugs in development, including fosmanogepix (a novel Gwt1 enzyme inhibitor), ibrexafungerp (a first-in-class triterpenoid), olorofim (a novel dihyroorotate dehydrogenase enzyme inhibitor), opelconazole (a novel triazole optimized for inhalation), and rezafungin (an echinocandin designed to be dosed once weekly). We focus on the mechanism of action and pharmacokinetics, as well as the spectrum of activity and stages of clinical development. We also highlight the potential future role of these drugs and unmet needs.

Mucormycosis in Indian COVID-19 Patients: Insight into Its Patho-Genesis, Clinical Manifestation, and Management Strategies

Mucormycosis in patients who have COVID-19 or who are otherwise immunocompromised has become a global problem, causing significant morbidity and mortality. Infection is debilitating and fatal, leading to loss of organs and emotional trauma. Radiographic manifestations are not specific, but diagnosis can be made through microscopic examination of materials collected from necrotic lesions. Treatment requires multidisciplinary expertise, as the fungus enters through the eyes and nose and may even reach the brain. Use of the many antifungal drugs available is limited by considerations of resistance and toxicity, but nanoparticles can overcome such limitations by reducing toxicity and increasing bioavailability. The lipid formulation of amphotericin-B (liposomal Am-B) is the first-line treatment for mucormycosis in COVID-19 patients, but its high cost and low availability have prompted a shift toward surgery, so that surgical debridement to remove all necrotic lesions remains the hallmark of effective treatment of mucormycosis in COVID-19. This review highlights the pathogenesis, clinical manifestation, and management of mucormycosis in patients who have COVID-19.

Invasive aspergillosis in critically ill patients: Review of definitions and diagnostic approaches

Invasive aspergillosis (IA) is an increasingly recognised phenomenon in critically ill patients in the intensive care unit, including in patients with severe influenza and severe coronavirus disease 2019 (COVID-19) infection. To date, there are no consensus criteria on how to define IA in the ICU population, although several criteria are used, including the AspICU criteria and new consensus criteria to categorise COVID-19-associated pulmonary aspergillosis (CAPA). In this review, we describe the epidemiology of IA in critically ill patients, most common definitions used to define IA in this population, and most common clinical specimens obtained for establishing a mycological diagnosis of IA in the critically ill. We also review the most common diagnostic tests used to diagnose IA in this population, and lastly discuss the most common clinical presentation and imaging findings of IA in the critically ill and discuss areas of further needed investigation.

Clinical Considerations of Isavuconazole Administration in High-Risk Hematological Patients: A Single-Center 5-Year Experience

Background

There are limited real-life data on isavuconazole prophylaxis and treatment of invasive mold infections (IMI) in hematological patients and allogeneic hematopoietic cell transplant (HCT) recipients.

Objectives

Primary objective was to describe the indications of real-life isavuconazole administration at a university hospital. Secondary objectives included the description of liver function tests and QTc interval between baseline and end of treatment (EOT), clinical outcomes and breakthrough IMI by the EOT.

Patients/Methods

This was a 5-year single-center retrospective study of all adult patients with acute myeloid leukemia and/or allogeneic HCT recipients who received isavuconazole as prophylaxis and/or treatment between June 1, 2016, and July 31, 2020.

Results

Among 30 identified patients, the indications for isavuconazole administration were adverse events associated with prior antifungal treatment (N: 18, 60%: hepatotoxicity, renal insufficiency, long QTc interval, neurotoxicity, and potential drug–drug interactions in 6, 4, 3, 1 and 4 patients, respectively), clinical efficacy (N: 5, 16.6%), and other reasons (N: 10, 33.3%; 5/10 patients treated with isavuconazole to facilitate hospital discharge with orally administered appropriate treatment). Alanine aminotransferase significantly decreased from baseline (mean: 129 IU/L, range: 73, 202) to a mean of 48 IU/L (range: 20, 80) by day 14 (P-value: 0.02), 23.5 IU/L (range: 20, 27) by day 28 (P-value: 0.03) and 16.5 IU/L (range: 16, 17) by day 42 (P-value: 0.009). The QTc interval decreased from baseline (mean: 456.8 ms, range: 390, 533) to EOT (mean: 433.8 ms, range: 400, 472; P-value: 0.03). The mean isavuconazole plasma concentration was 2.9 mg/L (range: 0.9, 6.7). There was no breakthrough IMI observed.

Conclusion

Isavuconazole is a safe and reliable antifungal agent in complex hematological patients, with relatively low hepatotoxicity and QTc interval shortening properties.

Microbiological and Molecular Diagnosis of Mucormycosis: From Old to New

Members of the order Mucorales may cause severe invasive fungal infections (mucormycosis) in immune-compromised and otherwise ill patients. Diagnosis of Mucorales infections and discrimination from other filamentous fungi are crucial for correct management. Here, we present an overview of current state-of-the-art mucormycosis diagnoses, with a focus on recent developments in the molecular field. Classical diagnostic methods comprise histology/microscopy as well as culture and are still the gold standard. Newer molecular methods are evolving quickly and display great potential in early diagnosis, although standardization is still missing. Among them, quantitative PCR assays with or without melt curve analysis are most widely used to detect fungal DNA in clinical samples. Depending on the respective assay, sequencing of the resulting PCR product can be necessary for genus or even species identification. Further, DNA-based methods include microarrays and PCR-ESI-MS. However, general laboratory standards are still in development, meaning that molecular methods are currently limited to add-on analytics to culture and microscopy.

Discovery of 1,2,3-selenadiazole analogues as antifungal agents using a scaffold hopping approach

With the increasing incidence of antifungal resistance, new antifungal agents having novel scaffolds hence are in an urgent need to combat infectious diseases caused by multidrug-resistant (MDR) pathogens. In this study, we reported the design, synthesis, and pharmacological evaluation of novel 1,2,3-selenadiazole analogues by scaffold hopping strategy. Preliminary results of antifungal activity demonstrated that the new class of compounds showed broad-spectrum fungistatic and fungicidal activity. Most importantly, these newly synthesized compounds can eliminate these azole-resistant fungi and inhibit the formation of C. albicans biofilm. In particular, compound S07 showed promising antifungal activity against five azole-resistant strains with MIC values ranging from 4 to 32 μg/mL. Then, further target identification and mechanistic studies indicated that representative compound S07 exert its inhibitory activity by inhibiting fungal lanosterol 14α-demethylase enzyme (CYP51). Interestingly, representative compounds showed low cytotoxicity on mammalian cell lines. In addition, the molecular docking studies elucidated the binding modes of these compounds toward CYP51. Altogether, these results suggest that compound S07 with novel skeleton is a promising CYP51 inhibitor for treatment of fungal infections.

Specificity Influences in (1→3)-β-d-Glucan-Supported Diagnosis of Invasive Fungal Disease

(1→3)-β-glucan (BDG) testing as an adjunct in the diagnosis of invasive fungal disease (IFD) has been in use for nearly three decades. While BDG has a very high negative predictive value in this setting, diagnostic false positives may occur, limiting specificity and positive predictive value. Although results may be diagnostically false positive, they are analytically correct, due to the presence of BDG in the circulation. This review surveys the non-IFD causes of elevated circulating BDG. These are in the main, iatrogenic patient contamination through the use of BDG-containing medical devices and parenterally-delivered materials as well as translocation of intestinal luminal BDG due to mucosal barrier injury. Additionally, infection with Nocardia sp. may also contribute to elevated circulating BDG. Knowledge of the factors which may contribute to such non-IFD-related test results can improve the planning and interpretation of BDG assays and permit investigational strategies, such as serial sampling and BDG clearance evaluation, to assess the likelihood of contamination and improve patient care.