Beta-D-glucan as a diagnostic adjunct for invasive fungal infections: validation, cutoff development, and performance in patients with acute myelogenous leukemia and myelodysplastic syndrome

Measurement of β-(1,3)-glucan in household dust samples using Limulus amebocyte assay and enzyme immunoassays: an inter-laboratory comparison

Environmental levels of β-(1,3)-glucan, an inflammatory fungal cell wall component, have been suggested to be related to respiratory symptoms. However there is currently little data comparing β-(1,3)-glucan detection methods and/or results obtained in different laboratories. The aim of this study was to compare levels of β-(1,3)-glucans detected in household dust samples (n = 40) using different extraction/detection methods (Limulus amebocyte assay (LAL), inhibition enzyme immunoassay (EIA) and sandwich EIA) in five different laboratories. Dust sample aliquots were sent to participating centres, extracted and analysed for β-(1,3)-glucan according to standard in-house procedures. Significant differences in the levels of β-(1,3)-glucan were observed between all laboratories (geometric mean levels ranging from 15.4 μg g (-1) to 4754 μg g(-1) dust; p < 0.0001) with the exception of those using a similar LAL method. The inhibition EIA used in laboratory D produced mean β-(1,3)-glucan measurements 80-100 times higher than the LAL assays, 4 times higher than the sandwich EIA in the same lab, 17.6 times those obtained with the EIA in lab E and 363 times those obtained in the EIA in laboratory C. Pearson's correlations generally showed significant associations between methods and laboratories, particularly those using similar methodology (R ranging from 0.5 to 0.8; p < 0.001), although some poor and even inverse correlations were observed. Bland-Altman analyses showed moderate to good agreement between most assays, although clear absolute differences were observed. In conclusion, although results obtained with different methods were often significantly correlated and therefore comparable in relative terms, direct comparison of results between laboratories and assays may be inappropriate.

Cerebrospinal fluid (1,3)-β-D-glucan detection as an aid for diagnosis of iatrogenic fungal meningitis

This case series highlights our experience with use of the Fungitell assay for quantifying (1,3)-β-d-glucan in cerebrospinal fluid during the current U.S. outbreak of fungal meningitis related to contaminated methylprednisolone acetate. This test may prove a useful adjunct in diagnosis and management of exposed patients.

Serum (1→3)-β-D-glucan levels in HIV-infected individuals are associated with immunosuppression, inflammation, and cardiopulmonary function

BACKGROUND

Translocation of gastrointestinal bacteria in HIV-infected individuals is associated with systemic inflammation, HIV progression, mortality, and comorbidities. HIV-infected individuals are also susceptible to fungal infection and colonization, but whether fungal translocation occurs and influences HIV progression or comorbidities is unknown.

METHODS

Serum (1→3)-β-D-glucan (BG) was measured by a Limulus Amebocyte Lysate assay (Fungitell) in 132 HIV-infected outpatients. Selected plasma cytokines and markers of peripheral T-cell activation were measured. Pulmonary function testing and Doppler echocardiography were performed. Relationship of high (≥40 pg/mL) and low (<40 pg/mL) levels of BG with HIV-associated variables, inflammation markers, and pulmonary function and pulmonary hypertension measures were determined.

RESULTS

Forty-eight percent of patients had detectable BG, and 16.7% had high levels. Individuals with high BG were more likely to have CD4 counts less than 200 cells/μL (31.8% vs. 8.4%, P = 0.002), had higher log10 HIV viral levels (2.85 vs. 2.13 log copies/mL, P = 0.004), and were less likely to use antiretroviral therapy (68.2% vs. 90.0%, P = 0.006). Plasma IL-8 (P = 0.033), TNF-α (P = 0.029), and CD8CD38 (P = 0.046) and CD8HLA-DR (P = 0.029) were also increased with high levels. Abnormalities in diffusing capacity (P = 0.041) and in pulmonary artery pressures (P = 0.006 for pulmonary artery systolic pressure and 0.013 for tricuspid regurgitant velocity) were more common in those with high BG.

CONCLUSIONS

We found evidence of peripheral fungal cell wall polysaccharides in an HIV-infected cohort. We also demonstrated an association between high serum BG, HIV-associated immunosuppression, inflammation, and cardiopulmonary comorbidity. These results implicate a new class of pathogen in HIV-associated microbial translocation and suggest a role in HIV progression and comorbidities.

Laboratory diagnosis of invasive aspergillosis: from diagnosis to prediction of outcome

Invasive aspergillosis (IA), an infection caused by fungi in the genus Aspergillus, is seen in patients with immunological deficits, particularly acute leukaemia and stem cell transplantation, and has been associated with high rates of mortality in previous years. Diagnosing IA has long been problematic owing to the inability to culture the main causal agent A. fumigatus from blood. Microscopic examination and culture of respiratory tract specimens have lacked sensitivity, and biopsy tissue for histopathological examination is rarely obtainable. Thus, for many years there has been a great interest in nonculture-based techniques such as the detection of galactomannan, β -D-glucan, and DNA by PCR-based methods. Recent meta-analyses suggest that these approaches have broadly similar performance parameters in terms of sensitivity and specificity to diagnose IA. Improvements have been made in our understanding of the limitations of antigen assays and the standardisation of PCR-based DNA detection. Thus, in more recent years, the debate has focussed on how these assays can be incorporated into diagnostic strategies to maximise improvements in outcome whilst limiting unnecessary use of antifungal therapy. Furthermore, there is a current interest in applying these tests to monitor the effectiveness of therapy after diagnosis and predict clinical outcomes. The search for improved markers for the early and sensitive diagnosis of IA continues to be a challenge.

The Role of Biomarkers for Diagnosis of and Therapeutic Decisions Related to Invasive Aspergillosis in Children

Invasive aspergillosis (IA) is a feared opportunistic infection for many immuncompromised children resulting in significant morbidity and mortality. Timely diagnosis based on traditional testing modalities and clinical evaluation has proven to be challenging. Assays designed to measure IA biomarkers such as galactomannan (GM) and beta-D-glucan (BG) represent a potential significant improvement in the ability to diagnose pediatric IA. However, as with any new diagnostic tool, clinicians need to be aware of the operating characteristics of these assays in order to apply them in the appropriate settings. Published adult and pediatric data regarding GM and BG testing are reviewed and guidance regarding the appropriate utility of these assays in children is offered.

Evaluation and Management of Bacterial and Fungal Infections Occurring in Patients with a Hematological Malignancy: A 2011 Update

Patients with a hematological malignancy are a heterogeneous patient population who are afflicted with diseases that range from rapidly fatal acute leukemia to indolent lymphoma or chronic leukemia. Treatment options for these patients range from observation to hematopoietic stem cell transplantation (HSCT), but all patients are more susceptible to infection. The problem of infection is dynamic with continued shifts in pathogenic organisms and microbial susceptibilities, new treatment regimens that further diminish immune function, and patients receiving treatment who are now older and frailer. The classic patterns of immunodeficiency for patients with a hematological malignancy include: periods of profound neutropenia, increased iatrogenic risks (i.e., central vascular catheters), and cellular immune suppression that affects HSCT recipients, patients with lymphoid malignancies, and those receiving treatment with corticosteroids or agents like alemtuzumab [1–4]. Recent advances in antimicrobial drug development, new technology, clinical trial results, and further clinical experience have enhanced the database on which to make infection prophylaxis and treatment decisions. However, the practicing clinician must remember that the majority of basic infection management principles for patients who are neutropenic remain unchanged.

What is the role of the (1→3)-β-D-glucan assay in the screening of patients undergoing autologous haematopoietic stem-cell transplantation?

The aim of this study is to determine the clinical contribution of (1→3)-β-d-glucan (BDG) screening in the case of patients undergoing autologous haematopoietic stem-cell transplantation (HSCT). The records at our stem-cell transplantation centre were reviewed to identify the patients who underwent autologous HSCT between April 2009 and December 2010. Patients were classified as having proven invasive aspergillosis (IA), probable IA, or possible IA on the basis of the criteria established by the European Organization for Research and Treatment of Cancer and Mycoses Study Group (independent of the BDG results). During the study period, the patients were screened for BDG twice a week from transplant (day 0) until engraftment. Three patients were diagnosed with probable IA and five were diagnosed with possible IA. A total of 354 serum samples from 79 patients who met the study inclusion criteria were used for statistical analysis. At the cut-off value of 80 pg ml(-1) , the sensitivity was 27.2% [95% confidence interval (CI); 7.3-60.6]; specificity, 94.4% (95% CI; 91.3-96.5); positive predictive value, 6.2%; and negative predictive, 93.7%. The clinical contribution of the BDG assay as a screening test was relatively limited in this cohort of patients undergoing autologous HSCT.

Overview of invasive fungal infections

The incidence of invasive fungal infections (IFIs) has seen a marked increase in the last two decades. This is especially evident among transplant recipients, patients suffering from AIDS, in addition to those in receipt of immunosuppressive therapy. Worryingly, this increased incidence includes infections caused by opportunistic fungi and emerging fungal infections which are resistant to or certainly less susceptible than others to standard antifungal agents. As a direct response to this phenomenon, there has been a resolute effort over the past several decades to improve early and accurate diagnosis and provide reliable screening protocols thereby promoting the administration of appropriate antifungal therapy for fungal infections. Early diagnosis and treatment with antifungal therapy are vital if a patient is to survive an IFI. Substantial advancements have been made with regard to both the diagnosis and subsequent treatment of an IFI. In parallel, stark changes in the epidemiological profile of these IFIs have similarly occurred, often in direct response the type of antifungal agent being administered. The effects of an IFI can be far reaching, ranging from increased morbidity and mortality to increased length hospital stays and economic burden.

(1-3)-β-D-glucan levels in candidiasis infections in the critically ill neonate

INTRODUCTION

The diagnosis of neonatal invasive Candida infections (ICIs) is problematic because the clinical signs are not specific and blood cultures are rarely positive. Hence, new diagnostic markers are needed.

OBJECTIVE

To assess the contribution of serum (1-3)-β-d-glucan (BDG) levels to the diagnosis of neonatal ICIs and to analyse the change in this parameter during antifungal therapy.

METHODS

This retrospective study (December 2010-March 2012) was performed at Amiens University Medical Center (Amiens, France). We included newborns in whom a BDG assay was performed for a suspected ICI and classified as infected (n = 18) or non-infected (n = 43).

RESULTS

Sixty-one patients (median (IQR) gestational age: 28.5 weeks (26.7-30.6); birth weight: 1000 g (910-1440)) were included. The BDG level was higher in the infected group (364 pg/ml (131-976) vs. 89 pg/ml (30-127); p < 0.001). The optimal BDG cut-off for distinguishing between non-infected and infected patients was 125 pg/ml (Se = 84%, Sp = 75%). The BDG level fell over the course of antifungal therapy.

CONCLUSION

Our study results suggest that BDG levels were increased in neonatal invasive Candida infections (cut-off for BDG positivity > 125 pg/ml). The change in the serum BDG levels may be of value in evaluating the efficacy of antifungal therapy.

Detection of (1, 3)-β-D-glucan in bronchoalveolar lavage and serum samples collected from immunocompromised hosts

The incidence of invasive fungal infections (IFI) has increased in recent years, especially among immunocompromised hosts (ICH). In 2003, the Fungitell(®) assay received FDA clearance for the presumptive diagnosis of IFI using serum and detects (1-3)-β-D-glucan, which is a major cell wall component of certain fungi (e.g., Candida, Aspergillus, and Pneumocystis). The goal of the current study was to assess the performance of the assay on bronchoalveolar lavage (BAL) fluid and serum to identify IFI in ICH. Patients were classified as having proven, probable, possible, or no IFI according to the European Organization for Research and Treatment of Cancer/Mycoses Study Group (EORTC/MSG) guidelines. Among 109 patients for whom the results of Fungitell were compared to the EORTC/MSG criteria, Fungitell showed a low positive predictive value for the identification of IFI from both BAL (20.0%) and serum (26.7%). However, the negative predictive value of Fungitell was significantly higher for both sample types (BAL, 83.0%; serum, 84.8%). Interestingly, the results of Fungitell were positive in BAL and serum in 7/8 (87.5%) patients diagnosed with Pneumocystis pneumonia (PcP) by real-time, non-nested PCR. These data indicate that the Fungitell assay has a low positive predictive value for the diagnosis of IFI in ICH, regardless of the specimen type that is tested. However, testing of serum samples by Fungitell may permit a rapid and noninvasive initial screening approach in patients with presumed PcP.

Canadian clinical practice guidelines for invasive candidiasis in adults

Candidemia and invasive candidiasis (C/IC) are life-threatening opportunistic infections that add excess morbidity, mortality and cost to the management of patients with a range of potentially curable underlying conditions. The Association of Medical Microbiology and Infectious Disease Canada developed evidence-based guidelines for the approach to the diagnosis and management of these infections in the ever-increasing population of at-risk adult patients in the health care system. Over the past few years, a new and broader understanding of the epidemiology and pathogenesis of C/IC has emerged and has been coupled with the availability of new antifungal agents and defined strategies for targeting groups at risk including, but not limited to, acute leukemia patients, hematopoietic stem cell transplants and solid organ transplants, and critical care unit patients. Accordingly, these guidelines have focused on patients at risk for C/IC, and on approaches of prevention, early therapy for suspected but unproven infection, and targeted therapy for probable and proven infection.

β-D-glucan surveillance with preemptive anidulafungin for invasive candidiasis in intensive care unit patients: a randomized pilot study

BACKGROUND

Invasive candidiasis (IC) is a devastating disease. While prompt antifungal therapy improves outcomes, empiric treatment based on the presence of fever has little clinical impact. Β-D-Glucan (BDG) is a fungal cell wall component detectable in the serum of patients with early invasive fungal infection (IFI). We evaluated the utility of BDG surveillance as a guide for preemptive antifungal therapy in at-risk intensive care unit (ICU) patients.

METHODS

Patients admitted to the ICU for ≥ 3 days and expected to require at least 2 additional days of intensive care were enrolled. Subjects were randomized in 3:1 fashion to receive twice weekly BDG surveillance with preemptive anidulafungin in response to a positive test or empiric antifungal treatment based on physician preference.

RESULTS

Sixty-four subjects were enrolled, with 1 proven and 5 probable cases of IC identified over a 2.5 year period. BDG levels were higher in subjects with proven/probable IC as compared to those without an IFI (117 pg/ml vs. 28 pg/ml; p<0.001). Optimal assay performance required 2 sequential BDG determinations of ≥ 80 pg/ml to define a positive test (sensitivity 100%, specificity 75%, positive predictive value 30%, negative predictive value 100%). In all, 21 preemptive and 5 empiric subjects received systemic antifungal therapy. Receipt of preemptive antifungal treatment had a significant effect on BDG concentrations (p< 0.001). Preemptive anidulafungin was safe and generally well tolerated with excellent outcome.

CONCLUSIONS

BDG monitoring may be useful for identifying ICU patients at highest risk to develop an IFI as well as for monitoring treatment response. Preemptive strategies based on fungal biomarkers warrant further study.

TRIAL REGISTRATION

Clinical Trials.gov NCT00672841.

Serum (1->3)-β-D-glucan measurement in coccidioidomycosis

The serum (1→3)-β-d-glucan assay has emerged as an important diagnostic test for invasive fungal disease. The utility of this assay in coccidioidomycosis has not been previously studied. Using a cutoff value of ≥80 pg/ml, we found the sensitivity (43.9%), specificity (91.1%), positive predictive value (81.8%), and negative predictive value (64.1%) to be similar to those of the assay in diagnosing other invasive mycoses.

Reactivity of the 1,3-β-D-glucan assay during bacteraemia: limited evidence from a prospective study

There are discrepancies in the retrospective studies published in literature of whether or not bacteraemia could lead to false positivity of 1,3-β-D (BG) glucan assay. We performed, for the first time, a prospective study evaluating the role of bacterial bloodstream infection to the reactivity of BG assay. Twenty-six episodes of bacteraemia that occurred in high-risk haematological patients were included in our study. Consecutive BG levels >80 pg ml(-1) were required for test positivity. Only 2 of 26 patients were BG positive - both with IFDs. Thus, we prospectively did not prove bacteraemia as the source of cross reactivity of BG assay in haematological patients.

Evaluation of fungal-specific fluorescent labeled echinocandin probes as diagnostic adjuncts

The diagnosis of invasive fungal infections from radiographic imaging is non-specific and problematic. As a first step toward increasing specificity, we describe the development of a broad-spectrum fungal-specific targeting molecule, which when modified with a fluorescent label fully retains its targeting properties, and provides a basis for future imaging applications.

(1,3)-β-D-glucan as a prognostic marker of treatment response in invasive candidiasis

BACKGROUND

(1,3)-β-D-glucan (BG) is a biomarker for invasive candidiasis (IC). The usefulness of BG level as a prognostic marker of treatment outcome is not well characterized.

METHODS

Two hundred fifty-seven patients with proven IC were enrolled in an anidulafungin study. Clinical and microbiological responses at the end of therapy were evaluated. Serial serum BG was measured. Correlation of initial and final BG levels with overall outcome was assessed in each patient.

RESULTS

Two hundred three patients had at least 2 BG levels and outcomes assessed. The majority of IC was caused by non-Candida albicans (53%) and found in the blood (84%). Overall, treatment success was 85%. In successfully treated patients, the mean ± SD initial and final BG were 573 ± 681 pg/mL and 499 ± 635 pg/mL (P = .03), respectively; while in treatment-failure patients, the levels were 1224 ± 1585 pg/mL and 1293 ± 1283 pg/mL (P = .29), respectively. A negative slope in BG levels correlated with a successful treatment outcome with a positive predictive value (PPV) of 90%, and a positive slope in BG levels correlated with treatment failure with a negative predictive value (NPV) of 90%. The cutoff value for initial BG <416 pg/mL has potential to predict treatment success with a PPV of 89%.

CONCLUSIONS

A decrease in BG levels during therapy is associated with treatment success. An initial BG of <416 pg/mL has potential to predict successful treatment outcomes. Baseline and consecutive serum BG measurements may be useful as prognostic markers of treatment outcome in patients with IC receiving primarily echinocandin therapy.

Laboratory diagnostics of invasive fungal infections: an overview with emphasis on molecular approach

Although invasive fungal diseases (IFDs) are relatively rare, they have become an increasingly common life-threatening complication in a variety of critically ill patients. Due to changes in treatment strategies, patterns of IFDs have changed substantially as well. Yeast infections have shifted toward a higher proportion of non-albicans Candida species, but their overall incidence has remained stable. In contrast, IFDs caused by molds, including particularly various species of Aspergillus, Fusarium, and Mucorales, have increased in number. In view of the growing incidence and the high mortality rates of IFDs, accurate diagnostic techniques permitting timely onset of adequate antifungal treatment are of paramount importance. Although conventional approaches such as microscopy, cultivation, histopathological examination, and imaging methods still represent the gold standard, the diagnosis remains difficult because of limited sensitivity and specificity. Noninvasive and culture-independent diagnostic techniques, including fungal antigen detection, and different molecular-based techniques are becoming increasingly important. Of the fungal surrogate markers such as cell wall components, galactomannan and (1,3)-β-D-glucan by commercially available diagnostic kits have become widely used, but the results are still controversial. A plethora of PCR-based diagnostic methods targeting different gene regions and exploiting a variety of amplicon detection tools have been published. Molecular assays have the capacity to overcome the limitations of other diagnostic approaches, but the current lack of methodological standardization and validation, together with not always clear interpretation of the results, has prevented broad application in the clinical setting.

Post-diagnostic kinetics of the (1 → 3)-β-D-glucan assay in invasive aspergillosis, invasive candidiasis and Pneumocystis jirovecii pneumonia

The kinetics of serum (1 → 3)-β-d-glucan (BG) following the diagnosis of invasive fungal disease and administration of antifungal therapy are poorly characterized. It is unknown whether early BG changes have prognostic implications. We assessed the post-diagnostic kinetics of BG in patients with an initial serum BG ≥80 pg/mL and at least one additional post-diagnostic BG value in the setting of invasive aspergillosis (IA, n=69), invasive candidiasis (IC, n=40), or Pneumocystis jirovecii pneumonia (PCP, n = 18), treated with antifungal therapy. Clinical failure of antifungal therapy and mortality were assessed at 6 and 12 weeks, and Cox modelling was used to assess the hazard of initial BG and change in BG at 1 or 2 weeks for these outcomes. In patients with at least two BG values, median initial BG was >500 pg/mL (interquartile range (IQR) 168 to >500; range 80 to >500) in IA, 136 pg/mL (IQR 88 to >500; range 31 to >500) in IC and >500 pg/mL (IQR 235 to >500; range 86 to >500) in PCP. In patients with at least two BG values through to 1 week after diagnosis, overall 1-week decline in BG was 0 pg/mL (IQR 0-53) in IA, 0 (IQR - 65 to 12) in IC and 17 (IQR 0-82) in PCP. Most patients with BG values through 6 and 12 weeks had persistent levels >80 pg/mL. Initial BG and the early trajectory of BG were not predictive of 6-week or 12-week clinical failure or mortality. Whereas BG eventually declines in patients with IA, IC and PCP, it lacks prognostic value within a clinically meaningful time frame.

Current knowledge of Trichosporon spp. and Trichosporonosis

Trichosporon spp. are basidiomycetous yeast-like fungi found widely in nature. Clinical isolates are generally related to superficial infections. However, this fungus has been recognized as an opportunistic agent of invasive infections, mostly in cancer patients and those exposed to invasive medical procedures. It is possible that the ability of Trichosporon strains to form biofilms on implanted devices, the presence of glucuronoxylomannan in their cell walls, and the ability to produce proteases and lipases are all factors likely related to the virulence of this genus and therefore may account for the progress of invasive trichosporonosis. Disseminated trichosporonosis has been increasingly reported worldwide and represents a challenge for both diagnosis and species identification. Phenotypic identification methods are useful for Trichosporon sp. screening, but only molecular methods, such as IGS region sequencing, allow the complete identification of Trichosporon isolates at the species level. Methods for the diagnosis of invasive trichosporonosis include PCR-based methods, Luminex xMAP technology, and, more recently, proteomics. Treating patients with trichosporonosis remains a challenge because of limited data on the in vitro and in vivo activities of antifungal drugs against clinically relevant species of the genus. Despite the mentioned limitations, the use of antifungal regimens containing triazoles appears to be the best therapeutic approach.

Correlation of clinical outcomes with β-glucan levels in patients with invasive candidiasis

The correlation of β-glucan (BG) levels with clinical outcomes in invasive candidiasis (IC) remains unknown. Patients with proven IC were followed prospectively from diagnosis to outcome with twice-weekly serum BG sampling. Correlation of BG with clinical outcome was assessed in each patient. BG levels tend to decrease in successfully treated patients and increase in treatment failures. BG levels may be useful as surrogates for outcome evaluation of IC.

Evaluation of multiplexed PCR and liquid-phase array for identification of respiratory fungal pathogens

Invasive fungal infections are the cause of serious morbidity and high mortality in immunocompromised patients. Early laboratory diagnostic options remain limited; however, rapid detection and accurate identification may improve outcome. Herein, multiplexed PCR followed by liquid-phase array was evaluated for detection and identification of common respiratory fungal pathogens, including Aspergillus fumigatus, Rhizopus microsporus, Scedosporium apiospermum and Fusarium solani. The limit of detection ranged 0.1-1 ng of DNA, depending on the fungus being tested. Primer cross-reactivity was seen for some fungi: Aspergillus flavus primers detected Aspergillus oryzae; Scedosporium apiospermum primers detected Paecilomyces lilacinus, and Aspergillus terreus primers detected S. apiospermum. PCR followed by liquid-phase array is potentially useful for the identification of clinically relevant fungal pathogens.

Invasive mold infections in chronic granulomatous disease: a 25-year retrospective survey

BACKGROUND

Invasive fungal infection (IFI) represents a life-threatening condition for patients with chronic granulomatous disease (CGD) and causes one-third of deaths in this population. This study offers a descriptive review of invasive mold infection (mIFI) in children with CGD over an extended period of time.

METHODS

In a cohort of patients with CGD registered in the French National database for Primary Immunodeficiency, we performed a retrospective review of proven mIFI episodes (European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases Mycoses Study Group 2008 criteria) occurring from 1984 through 2009.

RESULTS

Twenty-nine proven mIFIs were identified in 24 patients. Thirteen (54%) of 24 children were receiving itraconazole prophylaxis. Seven episodes were caused by Aspergillus fumigatus, 10 by Aspergillus nidulans, 2 by Aspergillus species, and 6 by other opportunistic molds (4 patients only had positive pathological examination findings). First proven mIFI occurred later in the group that received itraconazole than in the group without (median time to mIFI, 10 vs 4 years; P < .01), with a higher proportion of infections due to A. nidulans and other opportunistic molds (P < .05). Course of IFI was complex, with the median duration of therapy and hospitalization reaching 446 and 153 days, respectively. Combined antifungal therapy was commonly used. Four patients received geno-identical hematopoietic stem cell transplantation as salvage therapy. Global cure rate among the cohort reached 75%, but sequelae were frequent. Prognosis has improved over time (43% mortality during 1985-1990 vs 6% thereafter; P = .06). Mortality tended to be lower in the group that recieved itraconazole prophylaxis but at the cost of a longer duration of therapy among cured patients.

CONCLUSIONS

Management of mIFI remains challenging in patients with CGD, but significant improvements have been made over the past decade.

Accuracy of β-D-glucan for the diagnosis of Pneumocystis jirovecii pneumonia: a meta-analysis

Pneumocystis jirovecii pneumonia (PCP) can affect various types of immunocompromised patients. We sought to evaluate the diagnostic accuracy of (1→3)-β-D-glucan (BDG) for the diagnosis of PCP. We carried out a meta-analysis of relevant studies, identified through PubMed and Scopus. Eligible studies were those that reported BDG diagnostic data in cases with documented PCP and controls with other conditions. Cases of invasive fungal infections and healthy controls were excluded. We performed a bivariate meta-analysis of sensitivity and specificity and constructed a hierarchical summary receiver operating characteristics (HSROC) curve. Fourteen studies were included in the meta-analysis. BDG data were analysed for 357 PCP cases and 1723 controls. The average (95% confidence interval) sensitivity and specificity of BDG were 94.8% (90.8-97.1%) and 86.3% (81.7-89.9%), respectively. The positive and negative likelihood ratios were 6.9 (5.1-9.3) and 0.06 (0.03-0.11), respectively. The area under the HSROC curve was 0.965 (0.945-0.978). Serum BDG shows excellent sensitivity and very good specificity in the diagnosis of PCP. Still, in clinical practice the test results should be interpreted in the context of the underlying clinical characteristics of the individual patient.

Invasive mycoses: diagnostic challenges

Despite the availability of newer antifungal drugs, outcomes for patients with invasive fungal infections (IFIs) continue to be poor, in large part due to delayed diagnosis and initiation of appropriate antifungal therapy. Standard histopathologic diagnostic techniques are often untenable in at-risk patients, and culture-based diagnostics typically are too insensitive or nonspecific, or provide results after too long a delay for optimal IFI management. Newer surrogate markers of IFIs with improved sensitivity and specificity are needed to enable earlier diagnosis and, ideally, to provide prognostic information and/or permit therapeutic monitoring. Surrogate assays should also be accessible and easy to implement in the hospital. Several nonculture-based assays of newer surrogates are making their way into the medical setting or are currently under investigation. These new or up-and-coming surrogates include antigens/antibodies (mannan and antimannan antibodies) or fungal metabolites (d-arabinitol) for detection of invasive candidiasis, the Aspergillus cell wall component galactomannan used to detect invasive aspergillosis, or the fungal cell wall component and panfungal marker β-glucan. In addition, progress continues with use of polymerase chain reaction- or other nucleic acid- or molecular-based assays for diagnosis of either specific or generic IFIs, although the various methods must be better standardized before any of these approaches can be more fully implemented into the medical setting. Investigators are also beginning to explore the possibility of combining newer surrogate markers with each other or with more standard diagnostic approaches to improve sensitivity, specificity, and capacity for earlier diagnosis, at a time when fungal burden is still relatively low and more responsive to antifungal therapy.

Fungal infections: their diagnosis and treatment in transplant recipients

Systemic fungal infections typically occur in individuals who are seriously ill with recognized risk factors such as those frequently found in transplant recipients. Unfortunately, they are often diagnosed late, when the efficacy of the available treatments is low, often less than 50%, and the cost in terms of lives lost, hospital length of stay, and total hospital costs is substantially increased. The application of antifungal therapies associated with reported efficacy rates greater than 50% are those used prophylactically. When used prophylactically, these infections are reduced in greater than 95% of the expected cases. The choice of a prophylactic agent should be based upon its ease of administration, lack of adverse effects, reduced likelihood of potential drug interactions, and its efficacy in patients with established risk factors and comorbid disease processes that include renal, hepatic, and chronic pulmonary disease. The indications for the use of currently available antifungal agents, their adverse effects, drug interactions, ease of dosing, and applicability in patients with preexisting disease states, and especially in liver transplant recipients, are presented in this paper.

What should be the optimal cut-off of serum 1,3-β-D-glucan for the detection of invasive pulmonary aspergillosis in patients with haematological malignancies?

BACKGROUND

The detection of 1,3-β-d-glucan (BDG), a cell wall component of several medically important fungi, is a promising tool for the diagnosis of invasive pulmonary aspergillosis. The aim of this study was to evaluate the diagnostic accuracy of the BDG test in invasive pulmonary aspergillosis (IPA) by focusing on the optimal cut-off value.

METHODS

The records of the Infection Control Committee were reviewed to identify patients with haematological malignancies and stem cell transplantation who had at least 1 BDG (Fungitell kit) measurement during the period January 2008 through April 2011. The European Organization for Research and Treatment of Cancer and the Mycoses Study Group (EORTC/MSG) criteria (independent of BDG results) were used to categorize the patients with IPA. Patients with possible IPA were not included in the study.

RESULTS

A total of 128 patients (50 with proven or probable IPA) were included in the study. At the manufacturer's recommended cut-off value of 80 pg/ml, the sensitivity of BDG was 66% (95% CI 51.2-78.7), specificity 75.6% (95% CI 64.6-84.5), positive predictive value (PPV) 63.4%, and negative predictive value (NPV) 77.6%. A receiver operating characteristic (ROC) curve was constructed to define the optimum serum BDG cut-off for the diagnosis of IPA. At a cut-off value of 181 pg/ml, the sensitivity was 52% (95% CI 37.4-66.3), specificity 94.8% (95% CI 87.4-98.6), PPV 86.7%, and NPV 75.5%.

CONCLUSIONS

Although higher cut-off levels increased the specificity of the BDG test, sensitivity decreased to an unacceptable level; the commercially recommended cut-off value appears to be appropriate for screening purposes.

Serum galactomannan and (1->3)-β-D-glucan assays for patients with multiple myeloma and Waldenstrom's macroglobulinemia

We assessed the performance of galactomannan and (1→3)-β-d-glucan in 29 serum samples from patients with multiple myeloma and Waldenstrom's macroglobulinemia without invasive fungal disease to address issues of false positivity and uninterpretable results previously reported among patients with these conditions. Galactomannan and (1→3)-β-d-glucan assays were not falsely elevated in any patient. (1→3)-β-d-glucan assay results were uninterpretable in 24% of patients. Patients with IgG levels of >2,000 mg/dl had higher odds of uninterpretable (1→3)-β-d-glucan results.

Fungal diagnostics in pneumonia

Fungal pneumonia is increasingly common, particularly in highly immunosuppressed patients, such as solid organ or hematopoietic stem cell transplant recipients, and the diagnosis is evolving. Although standard techniques such as microscopy and culture remain the mainstays of diagnosis, relatively recent advances in serological and molecular testing are important additions to the field. This article reviews the laboratory tools used to diagnose fungal respiratory disease.

Interface of Candida albicans biofilm matrix-associated drug resistance and cell wall integrity regulation

Candida albicans frequently infects medical devices by growing as a biofilm, i.e., a community of adherent organisms entrenched in an extracellular matrix. During biofilm growth, Candida spp. acquire the ability to resist high concentrations of antifungal drugs. One recently recognized biofilm resistance mechanism involves drug sequestration by matrix β-1,3 glucan. Using a candidate gene approach, we investigated potential C. albicans β-1,3-glucan regulators, based on their homology to Saccharomyces cerevisiae, including SMI1 and protein kinase C (PKC) pathway components. We identified a role for the SMI1 in biofilm matrix glucan production and development of the associated drug resistance phenotype. This pathway appears to act through transcription factor Rlmp and glucan synthase Fks1p. The phenotypes of these mutant biofilms mimicked those of the smi1Δ/smi1Δ biofilm, and overexpression of FKS1 in the smi1Δ/smi1Δ mutant restored the biofilm resistant phenotype. However, control of this pathway is distinct from that of the upstream PKC pathway because the pkc1Δ/pkc1Δ, bck1Δ/bck1Δ, mkk2Δ/mkk2Δ, and mkc1Δ/mkc1Δ biofilms retained the resistant phenotype of the parent strain. In addition, resistance to cell-perturbing agents and gene expression data do not support a significant role for the cell wall integrity pathway during the biofilm formation. Here we show that Smi1p functions in conjunction with Rlm1p and Fks1p to produce drug-sequestering biofilm β-glucan. Our work provides new insight into how the C. albicans biofilm matrix production and drug resistance pathways intersect with the planktonic cell wall integrity pathway. This novel connection helps explain how pathogens in a multicellular biofilm community are protected from anti-infective therapy.

Multidisciplinary approach to the treatment of invasive fungal infections in adult patients. Prophylaxis, empirical, preemptive or targeted therapy, which is the best in the different hosts?

The high morbidity, mortality, and health care costs associated with invasive fungal infections, especially in the critical care setting and immunocompromised host, have made it an excellent target for prophylactic, empiric, and preemptive therapy interventions principally based on early identification of risk factors. Early diagnosis and treatment are associated with a better prognosis. In the last years there have been important developments in antifungal pharmacotherapy. An approach to the new diagnosis tools in the clinical mycology laboratory and an analysis of the use new antifungal agents and its application in different clinical situations has been made. Furthermore, an attempt of developing a state of the art in each clinical scenario (critically ill, hematological, and solid organ transplant patients) has been performed, trying to choose the best strategy for each clinical situation (prophylaxis, pre-emptive, empirical, or targeted therapy). The high mortality rates in these settings make mandatory the application of early de-escalation therapy in critically ill patients with fungal infection. In addition, the possibility of antifungal combination therapy might be considered in solid organ transplant and hematological patients.

Diagnostic accuracy of serum 1,3-β-D-glucan for pneumocystis jiroveci pneumonia, invasive candidiasis, and invasive aspergillosis: systematic review and meta-analysis

Serum 1,3-β-d-glucan (BG) assay may be helpful as a marker for the diagnosis of Pneumocystis jiroveci pneumonia (PJP) and invasive fungal infection (IFI). We conducted a systematic review to assess the diagnostic accuracy of this assay. We searched MEDLINE, Web of Science, Cochrane Collaboration databases, Ichushi-Web, reference lists of retrieved studies, and review articles. Our search included studies of serum BG assay that used (i) positive cytological or direct microscopic examination of sputum or bronchoalveolar lavage fluid for PJP and (ii) European Organization for Research and Treatment of Cancer or similar criteria for IFI as a reference standard and provided data to calculate sensitivity and specificity. Only major fungal infections such as invasive candidiasis and invasive aspergillosis were included in the IFI group. Twelve studies for PJP and 31 studies for IFI were included from January 1966 to November 2010. The pooled sensitivity, specificity, diagnostic odds ratio (DOR), and area under the summary receiver operating characteristic curve (AUC-SROC) for PJP were 96% (95% confidence interval [95% CI], 92% to 98%), 84% (95% CI, 83% to 86%), 102.3 (95% CI, 59.2 to 176.6) and 0.96 (95% CI, 0.94 to 0.99), respectively. No heterogeneity was found. For IFI, the values were 80% (95% CI, 77% to 82%), 82% (95% CI, 81% to 83%), 25.7 (95% CI, 15.0 to 44.1), and 0.88 (95% CI, 0.82 to 0.93). Heterogeneity was significant. The diagnostic accuracy of the BG assay is high for PJP and moderate for IFI. Because the sensitivity for PJP is particularly high, the BG assay can be used as a screening tool for PJP.

Early diagnosis of candidemia in intensive care unit patients with sepsis: a prospective comparison of (1→3)-β-D-glucan assay, Candida score, and colonization index

Introduction

The culture-independent serum (1→3)-β-D-glucan (BG) detection test may allow early diagnosis of invasive fungal disease, but its clinical usefulness needs to be firmly established. A prospective single-center observational study was conducted to compare the diagnostic value of BG assay, Candida score (CS), and colonization index in intensive care unit (ICU) patients at risk for Candida sepsis.

Methods

Of 377 patients, consecutively admitted to ICU for sepsis, 95 patients having an ICU stay of more than five days were studied. Blood specimens for fungal culture and BG measurement were obtained at the onset of clinical sepsis. For CS and colonization index calculations, surveillance cultures for Candida growth, and/or clinical data were recorded.

Results

Sixteen (16.8%) patients were diagnosed with proven invasive fungal infection, 14 with candidiasis (13 candidemia and 1 mediastinitis) and 2 with pulmonary aspergillosis or fusariosis. Of 14 invasive Candida-infection patients, 13 had a serum sample positive for BG, 10 had a CS value ≥3, and 7 a colonization index ≥0.5. In the 12 candidemic patients, a positive BG result was obtained 24 to 72 hrs before a culture-documented diagnosis of invasive candidiasis. The positive and negative predictive values for the BG assay were higher than those of CS and colonization index (72.2% versus 57.1% and 27.3%; and 98.7% versus 97.2% and 91.7%, respectively).

Conclusions

A single-point BG assay based on a blood sample drawn at the sepsis onset, alone or in combination withCS, may guide the decision to start antifungal therapy early in patients at risk for Candida infection.

Blood (1->3)-beta-D-glucan as a diagnostic test for HIV-related Pneumocystis jirovecii pneumonia

(See the editorial commentary by Morris and Masur, on pages 203-204.)

BACKGROUND

Improved noninvasive diagnostic tests for Pneumocystis jirovecii pneumonia (PCP) are needed. We evaluated the test characteristics of plasma (1 → 3)-β-D-glucan (β-glucan) for HIV-related PCP among a large group of patients presenting with diverse opportunistic infections (OIs).

METHODS

The study population included all 282 participants in AIDS Clinical Trials Group A5164, a study of early versus deferred antiretroviral therapy in conjunction with initial therapy of acute OIs. Baseline plasma samples were assayed for β-glucan, with standard assay reference values defining ≥ 80 pg/mL as positive. Before this analysis, diagnosis of PCP was independently adjudicated by 2 study investigators after reviewing reports from study sites.

RESULTS

A total of 252 persons had a β-glucan result that could be analyzed, 173 (69%) of whom had received a diagnosis of PCP. Median β-glucan with PCP was 408 pg/mL (interquartile range [IQR], 209-500 pg/mL), compared with 37 pg/mL (IQR, 31-235 pg/mL) without PCP (P < .001). The sensitivity of β-glucan dichotomized at 80 pg/mL for the diagnosis of PCP was 92% (95% confidence interval [CI], 87%-96%), and the specificity was 65% (95% CI, 53%-75%); positive and negative predictive values were 85% (95% CI, 79%-90%) and 80% (95% CI, 68%-89%) respectively, based on the study prevalence of 69% of patients with PCP. Rates of abnormal lactate dehyrogenase levels did not differ significantly between those with and without PCP.

CONCLUSIONS

Blood (1 → 3)-β-D-glucan is strongly correlated with HIV-related PCP. In some clinical centers, this may be a more sensitive test than the induced sputum examination and could reduce the need for both bronchoscopy and empirical therapy of PCP.

Diagnosis and therapy of Candida infections: joint recommendations of the German Speaking Mycological Society and the Paul-Ehrlich-Society for Chemotherapy

Invasive Candida infections are important causes of morbidity and mortality in immunocompromised and hospitalised patients. This article provides the joint recommendations of the German-speaking Mycological Society (Deutschsprachige Mykologische Gesellschaft, DMyKG) and the Paul-Ehrlich-Society for Chemotherapy (PEG) for diagnosis and treatment of invasive and superficial Candida infections. The recommendations are based on published results of clinical trials, case-series and expert opinion using the evidence criteria set forth by the Infectious Diseases Society of America (IDSA). Key recommendations are summarised here: The cornerstone of diagnosis remains the detection of the organism by culture with identification of the isolate at the species level; in vitro susceptibility testing is mandatory for invasive isolates. Options for initial therapy of candidaemia and other invasive Candida infections in non-granulocytopenic patients include fluconazole or one of the three approved echinocandin compounds; liposomal amphotericin B and voriconazole are secondary alternatives because of their less favourable pharmacological properties. In granulocytopenic patients, an echinocandin or liposomal amphotericin B is recommended as initial therapy based on the fungicidal mode of action. Indwelling central venous catheters serve as a main source of infection independent of the pathogenesis of candidaemia in the individual patients and should be removed whenever feasible. Pre-existing immunosuppressive treatment, particularly by glucocorticosteroids, ought to be discontinued, if feasible, or reduced. The duration of treatment for uncomplicated candidaemia is 14 days following the first negative blood culture and resolution of all associated symptoms and findings. Ophthalmoscopy is recommended prior to the discontinuation of antifungal chemotherapy to rule out endophthalmitis or chorioretinitis. Beyond these key recommendations, this article provides detailed recommendations for specific disease entities, for antifungal treatment in paediatric patients as well as a comprehensive discussion of epidemiology, clinical presentation and emerging diagnostic options of invasive and superficial Candida infections.