Cerebrospinal fluid and plasma (1-->3)-beta-D-glucan as surrogate markers for detection and monitoring of therapeutic response in experimental hematogenous Candida meningoencephalitis

Prognostic value of serial (1,3)-β-D-glucan measurements in ICU patients with invasive candidiasis

BACKGROUND

To determine whether a decrease in serum (1,3)-β-D-glucan (BDG) was associated with reduced mortality and to investigate the performance of BDG downslope in predicting clinical outcome in invasive candidiasis.

METHODS

Observational cohort study in ICU patients over a ten-year period (2012-2022) in Italy. Proven invasive candidiasis with at least 2 BDG determinations were considered.

RESULTS

In the study population of 103 patients (age 47 [35-62] years, SAPS II score 67 [52-77]) 68 bloodstream and 35 intrabdominal infections were recorded. Serial measurements showed that in 54 patients BDG decreased over time (BDG downslope group) while in 49 did not (N-BDG downslope group). Candida albicans was the pathogen most frequently isolated (61%) followed by C. parapsilosis (17%) and C. glabrata (12%), in absence of any inter-group difference. Invasive candidiasis related mortality was lower in BDG downslope than in N-BDG downslope group (17% vs 53%, p < 0.01). The multivariate Cox regression analysis showed the association of septic shock at infection occurrence and chronic liver disease with invasive candidiasis mortality (HR [95% CI] 3.24 [1.25-8.44] p = 0.02 and 7.27 [2.33-22.66] p < 0.01, respectively) while a BDG downslope was the only predictor of survival (HR [95% CI] 0.19 [0.09-0.43] p < 0.01). The area under the receiver operator characteristic curve for the performance of BDG downslope as predictor of good clinical outcome was 0.74 (p = 0.02) and our model showed that a BDG downslope > 70% predicted survival with both specificity and positive predictive value of 100%.

CONCLUSIONS

A decrease in serum BDG was associated with reduced mortality and a steep downslope predicted survival with high specificity in invasive candidiasis.

Case report: Chronic Candida albicans meningitis: a rare entity diagnosed by metagenomic next-generation sequencing

The aetiology of chronic aseptic meningitis is difficult to establish. Candida meningitis in particular is often diagnosed late, as cerebrospinal fluid (CSF) work-up and imaging findings are nonspecific. A 35-year-old patient with chronic aseptic meningitis, for which repeated microbiological testing of CSF was unrevealing, was finally diagnosed with Candida albicans (C. albicans) meningitis with cauda equina involvement using metagenomic next-generation sequencing (mNGS). This report highlights the diagnostic challenges and the difficulties of treating shunt-associated fungal meningitis.

Assessment of Antifungal Pharmacodynamics

Pharmacokinetic-pharmacodynamic (PK-PD) analysis is of central importance to the progress of an antifungal agent into clinical use. It is crucial to ensure that preclinical studies give the best possible prediction of the way drugs are likely to behave in a clinical setting. This review details the last 30 years of progress in terms of disease model design, efficacy outcome selection and translational modelling in antifungal PK-PD studies. The principles of how PK-PD parameters inform current clinical practice are also discussed, including a review of how these apply to existing and novel agents.

Caution when using 1,3, β-D-glucan in the CSF as a biomarker of Candida albicans meningitis

Relying on a biomarker to diagnose or follow-up the treatment of a Candida albicans meningitis would have an impact on patient management. The biomarker 1,3, β-D-glucan (BDG), developed for serum testing, shows inconsistent values when applied on cerebro-spinal fluid (CSF), and its use with the current protocol on CSF samples warrants caution.

Serologic biomarkers in Candida and Aspergillus infections of the central nervous system: a comparison of galactomannan, mannan, and β-1,3-D-gucan testing from serum and cerebrospinal fluid

BACKGROUND

The incidence of Aspergillus and Candida CNS infection, which are characterized by high mortality rates, is underestimated. This underdiagnosis presumably results from the limitations of available diagnostic tools and the need for invasive sampling. Little is known about the role of serologic biomarkers in the setting of CNS aspergillosis and candidiasis.

PATIENTS, MATERIALS, METHODS

Serum (19) and cerebrospinal fluid (CSF; 10) samples of 19 patients, whose CNS specimens yielded growth of Aspergillus or Candida, were analyzed for different biomarkers for fungal infection, i.e., galactomannan (GM), galactomannoprotein (GP), mannan, anti-mannan-antibodies, and β-1,3-D-glucan (BDG). Serum and CSF specimens of time-matched patients (two each for every case of fungal CNS infection) were included as controls.

RESULTS

GM, GP, and BDG seropositivity was found in one, two, and three of five cases of CNS aspergillosis. BDG and mannan / anti-mannan-antibody sensitivity in proven CNS candidiasis was 40 % and 20 %, respectively. Applying the serum cut off, sensitivity in CSF testing was 100 % for GM and BDG, and 50 % for mannans. While serum specificity for all assays ranged from 89 - 97 %, specificity for CSF BDG was only 70 %. No false positive GM results from CSF were obtained.

CONCLUSION

Sensitivity for diagnosing CNS aspergillosis and CNS candidiasis from serum is mediocre for all serological biomarkers. GM testing in CSF proved excellent performance. With a sensitivity of 100 % but a specificity of only 70 %, CSF BDG might be most useful when used in patients with a high pre-test probability.

Micafungin injection for the treatment of invasive candidiasis in pediatric patients under 4 months of age

INTRODUCTION

Neonates and young infants with invasive candidiasis are particularly at increased risk of dissemination including hematogenous Candida meningoencephalitis. The echinocandins including micafungin have emerged as a preferred agent in most cases of candidemia and invasive candidiasis but data in pediatric patients under 4 months of age are limited.

AREAS COVERED

In this report, we review the micafungin use in infants younger than 4 months of age. Animal studies as well as clinical data that support its use in neonatal candidiasis are reviewed. In addition, the status of FDA approval and the rationale of micafungin dosing recommendations in infants <4 months are discussed.

EXPERT OPINION

A dose of 4 mg/kg was approved for treatment of candidemia, Candida peritonitis and abscesses excluding meningoencephalitis or ocular involvement in patients younger than 4 months of age. However, because of the risk of central nervous system dissemination as well as the difficulty in establishing this diagnosis, this dose is inadequate to treat ill infants with candidemia. More studies are needed to establish the safety and efficacy of micafungin daily dose of at least 10 mg/kg in infants younger than 4 months of age when hematogenous Candida meningoencephalitis or ocular involvement cannot be excluded.

Challenging diagnosis of chronic cerebral fungal infection: Value of (1→3)-ß-D-glucan and mannan antigen testing in cerebrospinal fluid and of cerebral ventricle puncture

Primary fungal infection of the central nervous system (CNS) is rare but often associated with severe prognosis. Diagnosis is complicated since cerebrospinal fluid (CSF) samples obtained from lumbar puncture usually remain sterile. Testing for fungal antigens in CSF could be a complementary diagnostic tool. We conducted such measurements in CSF from patients with CNS fungal infection and now discuss the usefulness of ventricular puncture. Mannan and (1→3)ß-D-glucan (BDG) testing were retrospectively performed in CSF samples from three patients with proven chronic CNS fungal infection (excluding Cryptococcus), and subsequently compared to 16 controls. Results from lumbar punctures and those from cerebral ventricles were confronted. BDG detection was positive in all the CSF samples (from lumbar and/or ventricular puncture) from the three confirmed cases. In case of Candida infection, mannan antigen measurement was positive in 75% of the CSF samples. In the control group, all antigen detections were negative (n = 15), except for one false positive. Faced with suspected chronic CNS fungal infection, measurement of BDG levels appears to be a complementary diagnostic tool to circumvent the limitations of mycological cultures from lumbar punctures. In the event of negative results, more invasive procedures should be considered, such as ventricular puncture.

Efficacy and Pharmacokinetics of Fosmanogepix (APX001) in the Treatment of Candida Endophthalmitis and Hematogenous Meningoencephalitis in Nonneutropenic Rabbits

Candida endophthalmitis is a serious sight-threatening complication of candidemia that may occur before or during antifungal therapy. Hematogenous Candida meningoencephalitis (HCME) is also a serious manifestation of disseminated candidiasis in premature infants, immunosuppressed children, and immunocompromised adults. We evaluated the antifungal efficacy and pharmacokinetics of the prodrug fosmanogepix (APX001) in a rabbit model of endophthalmitis/HCME. Manogepix (APX001A), the active moiety of prodrug fosmanogepix, inhibits the fungal enzyme Gwt1 and is highly active in vitro and in vivo against Candida spp., Aspergillus spp., and other fungal pathogens. Plasma pharmacokinetics of manogepix after oral administration of fosmanogepix on day 6 at 25, 50, and 100 mg/kg resulted in maximum concentration of drug in plasma (C _max) of 3.96 ± 0.41, 4.14  ± 1.1, and 11.5 ± 1.1 μg/ml, respectively, and area under the concentration-time curve from 0 to 12 h (AUC_0-12) of 15.8 ± 3.1, 30.8 ± 5.0, 95.9 ± 14 μg·h/ml, respectively. Manogepix penetrated the aqueous humor, vitreous, and choroid with liquid-to-plasma ratios ranging from 0.19 to 0.52, 0.09 to 0.12, and 0.02 to 0.04, respectively. These concentrations correlated with a significant decrease in Candida albicans burden in vitreous (>10¹ to 10³ log CFU/g) and choroid (>10¹ to 10³ log CFU/g) (P ≤ 0.05 and P ≤ 0.001, respectively). The aqueous humor had no detectable C. albicans in treatment and control groups. The tissue/plasma concentration ratios of manogepix in meninges, cerebrum, cerebellum, and spinal cord were approximately 1:1, which correlated with a >10² to 10⁴ decline of C. albicans in tissue versus control (P ≤ 0.05). Serum and cerebrospinal fluid (CSF) (1→3)-β-d-glucan levels demonstrated significant declines in response to fosmanogepix treatment. These findings provide an experimental foundation for fosmanogepix in treatment of Candida endophthalmitis and HCME and derisk the clinical trials of candidemia and invasive candidiasis.

A Regulatory Review Approach for Evaluation of Micafungin for Treatment of Neonatal Candidiasis

Pathogenesis of neonatal candidiasis (NC) is distinct from systemic candidiasis in adults and older pediatric patients due to the significant incidence of central nervous system (CNS) involvement in neonates. Thus, although adequate and well-controlled trials in NC are often unfeasible due to difficulty enrolling patients, extrapolation of efficacy from antifungal drug trials in adults is generally not appropriate. However, treatment of NC is an area of great unmet need. We describe a regulatory review approach that combined the assessment of limited clinical efficacy, pharmacokinetics, and safety data from neonates and young infants along with microbiology outcomes and pharmacokinetic data from relevant nonclinical models of candidemia/invasive candidiasis to inform the use of micafungin in pediatric patients younger than 4 months of age, while communicating areas of remaining uncertainty in labeling.

Update on fungal infections of the central nervous system: emerging pathogens and emerging diagnostics

PURPOSE OF REVIEW

Fungal infections of the central nervous system (CNS) are relatively uncommon but associated with significant morbidity and mortality. We reviewed recent literature highlighting new approaches to management of these complex patients.

RECENT FINDINGS

Fungal infections are increasingly recognized as important causes of CNS disease in both immunocompromised and immunocompetent hosts. Globally, cryptococcal meningitis remains a leading cause of death in HIV-infected persons in resource-limited settings. Emerging fungal pathogens with increased virulence and resistance to numerous classes of antifungal agents have been identified and represent a management challenge. Newer diagnostic techniques focused on antigen detection or molecular amplification of fungal pathogens offer promise in the expediated diagnosis and treatment of CNS fungal infections.

SUMMARY

Meningitis and brain abscess because of invasive fungal pathogens are frequently fatal infections. Newer laboratory tests allowing antigen detection or molecular amplification from cerebrospinal fluid are more sensitive than culture and allow earlier initiation of effective therapy.

Combination Therapy with Ibrexafungerp (Formerly SCY-078), a First-in-Class Triterpenoid Inhibitor of (1→3)-β-d-Glucan Synthesis, and Isavuconazole for Treatment of Experimental Invasive Pulmonary Aspergillosis

Ibrexafungerp (formerly SCY-078) is a semisynthetic triterpenoid and potent (1→3)-β-d-glucan synthase inhibitor. We investigated the in vitro activity, pharmacokinetics, and in vivo efficacy of ibrexafungerp (SCY) alone and in combination with antimold triazole isavuconazole (ISA) against invasive pulmonary aspergillosis (IPA). The combination of ibrexafungerp and isavuconazole in in vitro studies resulted in additive and synergistic interactions against Aspergillus spp. Plasma concentration-time curves of ibrexafungerp were compatible with linear dose proportional profile. In vivo efficacy was studied in a well-established persistently neutropenic New Zealand White (NZW) rabbit model of experimental IPA. Treatment groups included untreated control (UC) rabbits and rabbits receiving ibrexafungerp at 2.5 (SCY2.5) and 7.5 (SCY7.5) mg/kg of body weight/day, isavuconazole at 40 (ISA40) mg/kg/day, or combinations of SCY2.5+ISA40 and SCY7.5+ISA40. The combination of SCY+ISA produced an in vitro synergistic interaction. There were significant in vivo reductions of residual fungal burden, lung weights, and pulmonary infarct scores in SCY2.5+ISA40, SCY7.5+ISA40, and ISA40 treatment groups versus those of the SCY2.5-treated, SCY7.5-treated, and UC (P < 0.01) groups. Rabbits treated with SCY2.5+ISA40 and SCY7.5+ISA40 had prolonged survival in comparison to that of the SCY2.5-, SCY7.5-, ISA40-treated, or UC (P < 0.05) groups. Serum galactomannan index (GMI) and (1→3)-β-d-glucan levels significantly declined in animals treated with the combination of SCY7.5+ISA40 in comparison to those of animals treated with SCY7.5 or ISA40 (P < 0.05). Ibrexafungerp and isavuconazole combination demonstrated prolonged survival, decreased pulmonary injury, reduced residual fungal burden, and lower GMI and (1→3)-β-d-glucan levels in comparison to those of single therapy for treatment of IPA. These findings provide an experimental foundation for clinical evaluation of the combination of ibrexafungerp and an antimold triazole for treatment of IPA.

Beta-glucans in advanced CKD: role in endotoxaemia and inflammation

Background/aims

(1–3)-β-D glucans (BG) are cellular components of yeasts and fungi. Elevated blood levels may be an adjunct in diagnosing invasive fungal infection, though can be high in dialysis patients without fungaemia. BG can also induce false positive signals in endotoxin detection assays (Limulus Amoebocyte Lysate [LAL] assay). We explored the relationship between BG levels, renal impairment, endotoxaemia and inflammation.

Methods

We measured serum BG levels, markers of inflammation and blood endotoxin levels in 20 controls, 20 with stages 1–3 chronic kidney disease (CKD), 20 with stages 4–5 CKD, 15 on peritoneal dialysis (PD) and 60 on haemodialysis (HD). Another 30 patients were studied before and after HD initiation.

Results

BG levels increased with advancing CKD, being highest in HD patients, 22% of whom had elevated levels (> 80 pg/ml). Levels increased significantly following HD initiation. Levels also correlated positively with CRP, TNFα, IL-6 levels, independently of CKD stage. Blood endotoxin was detectable by LAL assays in 10–53% of the CKD cohort, being most prevalent in the HD group, and correlating positively with BG levels. Adding BG blocking agent to the assay reduced endotoxin detection confining it to only 5% of HD patients. Levels of inflammatory markers were higher in those with detectable endotoxin - whether false- or true positives.

Conclusion

BG levels increased with decreasing renal function, being highest in dialysis patients. High BG levels were associated with false positive blood endotoxin signals, and with markers of inflammation, independently of CKD stage. The cause for high BG levels is unknown but could reflect increased gut permeability and altered mononuclear phagocytic system function.

Posaconazole Alone and in Combination with Caspofungin for Treatment of Experimental Exserohilum rostratum Meningoencephalitis: Developing New Strategies for Treatment of Phaeohyphomycosis of the Central Nervous System

Phaeohyphomycosis of the central nervous system (CNS) is a life-threatening infection associated with severe morbidity. New approaches to treatment of CNS phaeohyphomycosis are critically needed. We therefore studied posaconazole with or without caspofungin for treatment of experimental CNS phaeohyphomycosis caused by Exserohilum rostratum. Each clinical isolate of E. rostratum isolate was inoculated intracisternally with 1.0 × 10⁶ microconidia to fully anesthetized New Zealand White rabbits. Profound persistent neutropenia and immunosuppression were established and maintained using cytarabine and methylprednisolone, respectively. Study groups consisted of posaconazole suspension administered as oral formulation at 10 (PSC10) or 20 (PSC20) mg/kg, caspofungin (CFG) at 2 mg/kg intravenously (IV), combinations of PSC10+CFG or PSC20+CFG, and untreated controls (UC). Posaconazole produced a significant reduction of residual fungal burden of E. rostratum in cerebrum, cerebellum, spinal cord, and paravertebral muscle (p < 0.01), in comparison to UC. The combination of PSC10+CFG and PSC20+CFG achieved full clearance of residual fungal burden from cerebrum, while only PSC20+CFG treated rabbits demonstrated clearance from cerebellum, spinal cord, and paravertebral muscle (p < 0.01). These data correlated with the significant reduction of CSF (1→3)-β-d-glucan levels in rabbits treated with PSC20 and PSC20+CFG in comparison to those of UC (p < 0.05). Posaconazole alone or in combination with caspofungin demonstrated significant antifungal efficacy in the treatment of experimental E. rostratum meningoencephalitis and warrants further study for treatment of CNS phaeohyphomycosis.

Amphotericin B Penetrates into the Central Nervous System Through Focal Disruption of the Blood Brain Barrier in Experimental Hematogenous Candida Meningoencephalitis

Hematogenous Candida meningoencephalitis (HCME) is a life-threatening complication of neonates and immunocompromised children. Amphotericin B (AmB) shows poor permeability and low cerebrospinal fluid (CSF) concentrations, but is effective in treatment of HCME. In order to better understand the mechanism of CNS penetration of AmB, we hypothesized that AmB may achieve focally higher concentrations in infected CNS lesions. An in vitro BBB model was serially infected with C. albicans. Liposomal AmB (LAMB) or deoxycholate AmB (DAMB) at 5 μg/ml were then provided, vascular and CNS compartments were sampled 4h later. For in vivo correlation, rabbits with experimental HCME received a single dose of DAMB 1 mg/kg or LAMB 5 mg/kg, and were euthanized after 1, 3, 6 and 24h. Evans blue solution (2%) 2 ml/kg administered IV one hour prior to euthanasia stained infected regions of tissue but not histologically normal areas. AmB concentrations in stained and unstained tissue regions were measured using UPLC. For selected rabbits, MRI scans performed on days 1-7 postinoculation were acquired before and after IV bolus Gd-DTPA at 15min intervals through 2h post-injection. The greatest degree of penetration of DAMB and LAMB through the in vitro BBB occurred after 24h of exposure (P=0.0022). In vivo the concentrations of LAMB and DAMB in brain abscesses were 4.35±0.59 and 3.14±0.89-times higher vs. normal tissue (P≤0.019). MRI scans demonstrated that Gd-DTPA accumulated in infected areas with disrupted BBB. Localized BBB disruption in HCME allows high concentrations of AmB within infected tissues, despite the presence of low CSF concentrations.

The REDCap consortium: Building an international community of software platform partners

The Research Electronic Data Capture (REDCap) data management platform was developed in 2004 to address an institutional need at Vanderbilt University, then shared with a limited number of adopting sites beginning in 2006. Given bi-directional benefit in early sharing experiments, we created a broader consortium sharing and support model for any academic, non-profit, or government partner wishing to adopt the software. Our sharing framework and consortium-based support model have evolved over time along with the size of the consortium (currently more than 3200 REDCap partners across 128 countries). While the "REDCap Consortium" model represents only one example of how to build and disseminate a software platform, lessons learned from our approach may assist other research institutions seeking to build and disseminate innovative technologies.

The REDCap consortium: Building an international community of software platform partners

The Research Electronic Data Capture (REDCap) data management platform was developed in 2004 to address an institutional need at Vanderbilt University, then shared with a limited number of adopting sites beginning in 2006. Given bi-directional benefit in early sharing experiments, we created a broader consortium sharing and support model for any academic, non-profit, or government partner wishing to adopt the software. Our sharing framework and consortium-based support model have evolved over time along with the size of the consortium (currently more than 3200 REDCap partners across 128 countries). While the "REDCap Consortium" model represents only one example of how to build and disseminate a software platform, lessons learned from our approach may assist other research institutions seeking to build and disseminate innovative technologies.

Invasive Candidiasis in Infants and Children: Recent Advances in Epidemiology, Diagnosis, and Treatment

This paper reviews recent advances in three selected areas of pediatric invasive candidiasis: epidemiology, diagnosis, and treatment. Although the epidemiological trends of pediatric invasive candidiasis illustrate a declining incidence, this infection still carries a heavy burden of mortality and morbidity that warrants a high index of clinical suspicion, the need for rapid diagnostic systems, and the early initiation of antifungal therapy. The development of non-culture-based technologies, such as the T2Candida system and (1→3)-β-d-glucan detection assay, offers the potential for early laboratory detection of candidemia and CNS candidiasis, respectively. Among the complications of disseminated candidiasis in infants and children, hematogenous disseminated Candida meningoencephalitis (HCME) is an important cause of neurological morbidity. Detection of (1→3)-β-d-glucan in cerebrospinal fluid serves as an early diagnostic indicator and an important biomarker of therapeutic response. The recently reported pharmacokinetic data of liposomal amphotericin B in children demonstrate dose–exposure relationships similar to those in adults. The recently completed randomized clinical trial of micafungin versus deoxycholate amphotericin B in the treatment of neonatal candidemia provides further safety data for an echinocandin in this clinical setting.

Evaluation of the (1,3)-β-D-glucan assay for the diagnosis of neonatal invasive yeast infections

Most newborns in the neonatal intensive care unit (NICU) are premature and at risk of invasive fungal infections (IFIs). Invasive yeast infections (IYIs) are the most common fungal infections in this population. These infections are difficult to diagnose because symptoms are nonspecific, and the sensitivity of blood cultures is low. The serum (1,3)-β-D-glucan (BDG) assay provides a reliable marker for the diagnosis of IFIs in adults with haematological malignancies. We assessed the diagnostic performance of this test in neonatal IYIs and its contribution to the monitoring of antifungal treatment. A retrospective study was performed in the NICU of the French University Hospital of Amiens from February 2012 to February 2014. Forty-seven neonates (33 males, 14 females) with a median gestational age of 30 weeks (IQR: 27-31) and median birth weight of 1200 g (IQR: 968-1700) were included and divided into three groups: 21 control neonates (CTRL), 20 neonates with probable IYI (PB), and six with proven IYI (PV). Median BDG levels were significantly higher in the global IYI group (PB + PV): 149 pg/ml (IQR: 85-364) vs. CTRL group: 39 pg/ml (IQR: 20-94) (P < .001). The optimal cut-off was 106 pg/ml (sensitivity 61.5%; specificity 81%). BDG levels decreased with antifungal treatment. BDG was detectable in cerebrospinal fluid, but the interest of this for diagnostic purposes remains unclear. Our results suggest that the BDG assay may be useful for the early identification of IYIs in neonates and for monitoring antifungal therapy efficacy.

Combination Therapy with Isavuconazole and Micafungin for Treatment of Experimental Invasive Pulmonary Aspergillosis

Invasive pulmonary aspergillosis (IPA) is an important cause of morbidity and mortality in immunocompromised patients. We hypothesized that simultaneous inhibition of biosynthesis of ergosterol in the fungal cell membrane and (1→3)-β-d-glucan in the cell wall, respectively, by the antifungal triazole isavuconazole (ISA) and the echinocandin micafungin (MFG) may result in improved outcomes in experimental IPA in persistently neutropenic rabbits. Treatments included ISA at 20 mg/kg of body weight/day (ISA20), 40 mg/kg/day (ISA40), and 60 mg/kg/day (ISA60); MFG at 2 mg/kg/day (MFG2); combinations of ISA20 and MFG2, ISA40 and MFG2, and ISA60 and MFG2; and no treatment (untreated controls [UC]). The galactomannan index (GMI) and (1→3)-β-d-glucan levels in serum were measured. The residual fungal burden (number of CFU per gram) was significantly reduced in ISA20-, ISA40-, ISA60-, ISA20-MFG2-, ISA40-MFG2-, and ISA60-MFG2-treated rabbits compared with that in MFG2-treated or UC rabbits (P < 0.01). Measures of organism-mediated pulmonary injury, lung weights, and pulmonary infarct score were lower in ISA40-MFG2-treated rabbits than in rabbits treated with ISA40 or MFG2 alone (P < 0.01). Survival was prolonged in ISA40-MFG2-treated rabbits in comparison to those treated with ISA40 or MFG2 alone (P < 0.01). These outcome variables correlated directly with significant declines in GMI and serum (1→3)-β-d-glucan levels during therapy. The GMI correlated with measures of organism-mediated pulmonary injury, lung weights (r = 0.764; P < 0.001), and pulmonary infarct score (r = 0.911; P < 0.001). In summary, rabbits receiving combination therapy with isavuconazole and micafungin demonstrated a significant dose-dependent reduction in the residual fungal burden, decreased pulmonary injury, prolonged survival, a lower GMI, and lower serum (1→3)-β-d-glucan levels in comparison to rabbits receiving isavuconazole or micafungin as a single agent.

Translational Development and Application of (1→3)-β-d-Glucan for Diagnosis and Therapeutic Monitoring of Invasive Mycoses

Early diagnosis and prompt initiation of appropriate antimicrobial therapy are crucial steps in the management of patients with invasive fungal infections. However, the diagnosis of invasive mycoses remains a major challenge in clinical practice, because presenting symptoms may be subtle and non-invasive diagnostic assays often lack sensitivity and specificity. Diagnosis is often expressed on a scale of probability (proven, probable and possible) based on a constellation of imaging findings, microbiological tools and histopathology, as there is no stand-alone assay for diagnosis. Recent data suggest that the carbohydrate biomarker (1→3)-β-d-glucan may be useful in both the diagnosis and therapeutic monitoring of invasive fungal infections due to some yeasts, molds, and dimorphic fungi. In this paper, we review recent advances in the use of (1→3)-β-d-glucan to monitor clinical response to antifungal therapy and explore how this assay may be used in the future.

Molecular diagnosis of invasive mycoses of the central nervous system

INTRODUCTION

In September 2012, the Centers for Disease Control and Prevention (CDC) began investigating an outbreak of fungal meningitis among patients who had received contaminated preservative-free methyl prednisolone acetate injections from the New England Compounding Center in Framingham, Massachusetts. Thousands of patients were potentially exposed to tainted corticosteroids, but establishing the diagnosis of fungal meningitis during the nationwide outbreak was difficult because little was known about the natural history of the disease. Areas covered: The challenges associated with this outbreak highlighted the need for rapid and reliable methodologies to assist in the diagnosis of invasive mycoses of the central nervous system (IMCNS), which may be devastating and difficult to treat. In this paper, we review the causative agents of these potentially-lethal infections, which include cryptococcal meningitis, cerebral aspergillosis, and hematogenous Candida meningoencephalitis. Expert commentary: While microscopy, culture, and histopathologic identification of fungal pathogens remain the gold standard for diagnosis, new platforms and species-specific assays have recently emerged, including lateral flow immunoassays (LFA), matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), and multiplex PCR in conjunction with magnetic resonance (MR) to potentially aid in the diagnosis of IMCNS.

Successful treatment of Aspergillus ventriculitis through voriconazole adaptive pharmacotherapy, immunomodulation, and therapeutic monitoring of cerebrospinal fluid (1→3)-β-D-glucan

Aspergillus ventriculitis is an uncommon but often fatal form of invasive aspergillosis of the central nervous system (CNS). As little is known about the diagnosis, treatment, and outcome of this potentially lethal infection, we report the strategies used to successfully treat Aspergillus ventriculitis complicating a pineal and pituitary germinoma with emphasis on the critical role of adaptive pharmacotherapy of voriconazole and serial monitoring of (1→3)-β-D-glucan in cerebrospinal fluid. We describe several rationally based therapeutic modalities, including adaptive pharmacotherapy, combination therapy, sargramostim-based immunomodulation, and biomarker-based therapeutic monitoring of the CNS compartment. Through these strategies, our patient remains in remission from both his germinoma and Aspergillus ventriculitis making him one of the few survivors of Aspergillus ventriculitis.

Is Endotoxemia in Stable Hemodialysis Patients an Artefact? Limitations of the Limulus Amebocyte Lysate Assay and Role of (1→3)-β-D Glucan

Background

Elevated blood endotoxin levels are frequently reported in the dialysis population and are strongly linked with inflammation, a major predictor of mortality. Virtually all studies have employed the Limulus Amoebocyte Lysate (LAL) assay to detect endotoxin. However this assay is not endotoxin-specific and can be activated by (1→3)-β-glucan (BG), a component of fungal cell walls leading to false positive signals. Very few studies have taken account of this. We examined the influence of BG-based activation of the LAL assay on the detection of endotoxemia in this setting.

Method

We measured plasma endotoxin levels in 50 hemodialysis patients with and without the use of BG-blocking buffers. These buffers inhibit BG activation of the LAL assay to ensure that any signal detected is endotoxin-specific. Blood samples were measured for BG, interleukin-6 (IL-6), tumor necrosis factor-alfa (TNF-α) to examine the association between endotoxin signals, BG and inflammation.

Results

Endotoxin signals were detected in 50% of patients. On repeat measurement with a BG-blocking buffer, all detected endotoxin signals were extinguished. No patient had detectable endotoxemia. Plasma BG levels were significantly elevated in 58% of patients and were higher in those with detectable endotoxin signals using the LAL assay without BG-blocking buffers (78vs.54pg/mL;p<0.001). Endotoxin signal and BG levels did not correlate with levels of TNF-α or IL-6.

Conclusion

Use of the LAL assay for blood endotoxin detection in dialysis patients has its limitations due to high blood BG. Endotoxemia frequently reported in non-infected hemodialysis patients may be artefactual due to BG interference.

(1→3)-β-d-Glucan in Cerebrospinal Fluid as a Biomarker for Candida and Aspergillus Infections of the Central Nervous System in Pediatric Patients

BACKGROUND

Fungal infections of the central nervous system (FICNS) are important causes of morbidity and mortality among immunocompromised pediatric patients. Standard diagnostic modalities lack the sensitivity for detecting and therapeutically monitoring these life-threatening diseases. Current molecular methods remain investigational. (1→3)-β-d-glucan (BDG) is a cell wall component found in several fungal pathogens, including Candida and Aspergillus spp. Detecting BDG in cerebrospinal fluid (CSF) may be an important approach for detecting and therapeutically monitoring FICNS. To date, there has been no study that has investigated the effectiveness of CSF BDG as a diagnostic and therapeutic marker of FICNS in children.

METHODS

Serial BDG levels were measured in serum and CSF samples obtained from pediatric patients (aged 0-18 years) with a diagnosis of probable or proven Candida or Aspergillus CNS infection.

RESULTS

Nine cases of FICNS were identified in patients aged 1 month to 18 years. Two patients were infected with an Aspergillus species, and 7 patients were infected with a Candida species. All the patients at baseline had detectable BDG in their CSF. Among 7 patients who completed therapy for an FICNS, all elevated CSF BDG levels decreased to <31 pg/mL. At the time of this writing, 1 patient was still receiving therapy and continued to have elevated BDG levels. One patient died from overwhelming disseminated candidiasis. The lengths of therapy for these 9 children ranged from 2 weeks to 28 months.

CONCLUSION

The BDG assay is useful in diagnosing and therapeutically monitoring Candida and Aspergillus CNS infections in pediatric patients.

Intermittent Dosing of Micafungin Is Effective for Treatment of Experimental Disseminated Candidiasis in Persistently Neutropenic Rabbits

BACKGROUND

The current standard of treatment of invasive candidiasis with echinocandins requires once-daily therapy. To improve quality of life, reduce costs, and improve outcome, we studied the pharmacokinetics (PK), efficacy, and safety of alternate dosing regimens of micafungin (MFG) for the treatment of experimental subacute disseminated candidiasis.

METHODS

MFG was administered for 12 days starting 24 hours after intravenous inoculation of 1 × 10(3) Candida albicans blastoconidia. Study groups consisted of MFG at 1 mg/kg every 24 hours (MFG1), 2 mg/kg every 48 hours (MFG2), and 3 mg/kg every 72 hours (MFG3), and untreated controls. PK of MFG were determined on day 7 by high-performance liquid chromatography and modeled using nonparametric adaptive grid program. A 2-compartment PK model with volume of the central compartment (Vc), clearance (SCL), and the intercompartmental rate constants Kcp and Kpc was used. The fungal burden in 7 tissues was determined 312 hours after the initiation of therapy.

RESULTS

PK of MFG were linear and the parameter means ± SD were Vc = 0.41 ± 0.18 L, Kcp = 2.80 ± 1.55/hour, Kpc = 1.71 ± 0.93/hour, and SCL = 0.16 ± 0.003 L/hour (r(2) = 0.99). The area under the plasma drug concentration - time curve for MFG1, MFG2, and MFG3 was 198.7 ± 19.8, 166.3 ± 36.7, and 192.8 ± 46.2 mg × hour/L, respectively (P = .24). All treatment groups showed significant and comparable resolution of (1→3)-β-D-glucan levels and clearance of C. albicans from liver, spleen, kidney, brain, lung, vitreous humor, and vena cava in comparison to untreated controls (P ≤ .05). There were no differences in hepatic or renal function among study groups.

CONCLUSIONS

Less fractionated MFG regimens of every 48 and 72 hours are safe and as effective in experimental disseminated candidiasis as once-daily therapy in neutropenic hosts.

Cerebrospinal Fluid (1,3)-Beta-d-Glucan Testing Is Useful in Diagnosis of Coccidioidal Meningitis

Diagnosing coccidioidal meningitis (CM) can be problematic owing to its infrequency and/or a delay in the positivity of a cerebrospinal fluid (CSF) culture or CSF antibody, particularly if the primary coccidioidal infection is unrecognized. We tested 37 CSF specimens, 26 from patients with confirmed CM and 11 from patients with suspected microbial meningitis without fungal diagnosis, for (1,3)-beta-glucan (BG). BG in CM CSF specimens ranged from 18 to 3,300 pg/ml and in controls ranged from <3.9 to 103 pg/ml. Diagnostic performance was determined using a 31-pg/ml cutoff (the bottom of the serum range according to the directions for the commercial kit, although further serial dilutions of the standard indicated linearity to 3.9). Sensitivity was 96%, specificity was 82%, positive and negative predictive values were 93% and 90%, and the area under the receiver operating characteristic curve was 0.937. Fifteen of 15 samples of >103 pg/ml were CM. The one false-negative specimen was from a patient with a pseudosyrinx, without inflammatory evidence of meningitis activity. Serial samples from some patients were positive at ≤8 years, indicating no loss of positivity with chronicity. Samples stored frozen since 2000 included those with 2 of the 3 highest values, indicating that fresh samples not required. A previous study indicated serum sensitivities of 53% in acute, 50% in resolved, and 83% in disseminated and meningeal coccidioidomycosis. Three studies of other fungal meningitides ranged from 86 to 1,524 pg/ml CSF, with 37 controls of <4 to 115 pg/ml CSF. CSF BG analysis had good diagnostic performance in CM. CSF BG testing can be useful in CM, and a commercial kit is available. It will be of interest to correlate this with course, treatment, outcome, inflammation, and antigen. The only mycoses with common central nervous system (CNS) involvement are cryptococcal and coccidioidal, so CSF BG screening can be useful in meningitis diagnosis.

Voriconazole treatment of Candida tropicalis meningitis: persistence of (1,3)-β-D-glucan in the cerebrospinal fluid is a marker of clinical and microbiological failure: A case report

INTRODUCTION

Infections are still the most common complications of cerebral shunt procedures. Even though fungal etiologies are considered to be rare, they are associated with significant morbidity and mortality. Due to their uncommonness, diagnostic procedures and optimal therapy are poorly defined. We report a case of Candida tropicalis infection of ventriculo-peritoneal cerebrospinal fluid (CSF) shunt in a 49-year-old immune competent male treated with voriconazole (VOR).

METHODS

Microbiological and CSF markers (1,3-b-D-glucan-BDG) of fungal infection, biofilm production capacity, sensitivity of serial isolates of the pathogen, and the concentration of the antifungal drug have been monitored and related to the clinical course of this infection.

RESULTS

Despite appropriate treatment with VOR, in terms of adequate achieved CSF drug concentrations and initial effective therapeutic response, loss of VOR susceptibility of the C tropicalis and treatment failure were observed.

CONCLUSION

Biofilm production of the C. tropicalis isolate might have had a significant role in treatment failure. Of interest, clinical and microbiological unfavorable outcome was anticipated by persistence of BDG in CSF. Rising titers of this marker were associated with relapse of fungal infection.

Pharmacokinetics and Concentration-Dependent Efficacy of Isavuconazole for Treatment of Experimental Invasive Pulmonary Aspergillosis

We studied the pharmacokinetics and efficacy of the broad-spectrum triazole isavuconazole for the treatment of experimental invasive pulmonary aspergillosis (IPA) in persistently neutropenic rabbits. Treatment started 24 h after endotracheal administration of Aspergillus fumigatus inoculum; study subjects included rabbits receiving orally administered prodrug isavuconazonium sulfate (BAL8557) equivalent to active moiety isavuconazole (ISA; BAL4815) at 20 (ISA20), 40 (ISA40), and 60 (ISA60) mg/kg (of body weight)/day, with an initial loading dose of 90 mg/kg (ISA90), and untreated rabbits (UC). There were significant concentration-dependent reductions of residual fungal burden (log CFU/gram) and of organism-mediated pulmonary injury, lung weights, and pulmonary infarct scores in ISA40- and ISA60-treated rabbits in comparison to those of UC (P < 0.001). ISA20-treated (P < 0.05), ISA40-treated, and ISA60-treated (P < 0.001) rabbits demonstrated significantly prolonged survival in comparison to that of UC. ISA40- and ISA60-treated animals demonstrated a significant decline of serum (1→3)-β-d-glucan levels (P < 0.05) and galactomannan indices (GMIs) during therapy following day 4 in comparison to progressive GMIs of UC (P < 0.01). There also were significantly lower concentration-dependent GMIs in bronchoalveolar lavage (BAL) fluid from ISA40- and ISA60-treated rabbits (P < 0.001). There was a direct correlation between isavuconazole plasma area under the concentration-time curve from 0 to 24 h (AUC0-24) and residual fungal burdens in lung tissues, pulmonary infarct scores, and total lung weights. In summary, rabbits treated with isavuconazole at 40 and 60 mg/kg/day demonstrated significant dose-dependent reduction of residual fungal burden, decreased pulmonary injury, prolonged survival, lower GMIs in serum and BAL fluid, and lower serum (1→3)-β-d-glucan levels.

Clinical Practice Guideline for the Management of Candidiasis: 2016 Update by the Infectious Diseases Society of America

It is important to realize that guidelines cannot always account for individual variation among patients. They are not intended to supplant physician judgment with respect to particular patients or special clinical situations. IDSA considers adherence to these guidelines to be voluntary, with the ultimate determination regarding their application to be made by the physician in the light of each patient's individual circumstances.

Chronic Invasive Aspergillus Sinusitis and Otitis with Meningeal Extension Successfully Treated with Voriconazole

Invasive aspergillosis (IA) is a severe disseminated fungal disease that occurs mostly in immunocompromised patients. However, central nervous system IA, combining meningitis and skull base involvement, does not occur only in groups with classic risk factors for IA; patients with chronic renal failure and diabetes mellitus are also at risk for more chronic forms. In both of our proven IA cases, voriconazole monotherapy was effective without surgery, and cerebrospinal fluid and serum 1,3-β-d-glucan test results were initially positive, in contrast to galactomannan antigen results.

Detection of High Cerebrospinal Fluid Levels of (1→3)-β-d-Glucan in Cryptococcal Meningitis

(1→3)-Beta-D-glucan was detected in high levels in cerebrospinal fluid, and to lesser extent in serum, among HIV-infected persons with cryptococcal meningitis.

Background

 (1→3)-β-d-Glucan (BDG) is a helpful diagnostic marker for many invasive fungal infections. However, BDG is not thought to be useful in diagnosing cryptococcosis. We evaluated the utility of BDG as an adjunct diagnostic tool for patients infected with human immunodeficiency virus (HIV) and presenting with suspected cryptococcal meningitis.

Methods

 The Fungitell assay was used to measure BDG concentrations in cerebrospinal fluid (CSF) (n = 177) and serum (n = 109) of HIV-infected Ugandans and South Africans with suspected meningitis. Correlations between BDG concentrations and quantitative CSF cryptococcal cultures, CSF cryptococcal antigen (CRAG) titers, and 18 different CSF cytokine concentrations were assessed using non-parametric tests. Mixed models evaluated longitudinal changes in CSF BDG concentrations. Survival analyses were used to evaluate BDG's relationship with mortality.

Results

 The Fungitell BDG assay provided 89% sensitivity and 85% specificity in CSF for cryptococcal meningitis. Serum sensitivity was suboptimal (79%). Cerebrospinal fluid BDG concentrations at diagnosis were median (interquartile range) 343 (200–597) pg/mL in cryptococcal patients and 37 (23–46) pg/mL in patients without cryptococcosis. Sensitivity in CSF improved to 98% (53 of 54) when initial fungal burdens were ≥10 000 colony-forming units/mL. (1→3)-β-d-Glucan normalized rapidly after initiating antifungal therapy. Baseline BDG concentrations correlated with CSF fungal burden (rho = 0.820; P < .001), CSF CRAG lateral flow assay titers (rho = 0.780, P < .001), and monocyte chemotactic protein-1 levels in CSF (P = .047). In patients with cryptococcal meningitis, BDG ≥500 pg/mL at diagnosis was associated with increased 10-week mortality.

Conclusions

 (1→3)-β-d-Glucan is detectable in the CSF of HIV-infected patients with Cryptococcus, and it may provide useful prognostic information. Sensitivity is less than CRAG; however, BDG normalizes rapidly, unlike CRAG, making BDG potentially useful in diagnosing recurrent episodes.

Non-cultural methods for the diagnosis of invasive fungal disease

Invasive fungal diseases carry a high mortality risk which can be reduced by early treatment. Diagnosing invasive fungal diseases is challenging, because invasive methods for obtaining histological samples are frequently not feasible in thrombocytopenic immunocompromised patients, while fungal cultures have low sensitivity and a long turn-around time. Non-cultural methods are fundamental for a rapid diagnosis of invasive fungal diseases and they include assays based on the detection of fungal antigens (galactomannan, Aspergillus-lateral flow device, [1,3]-β-D-glucan, mannan), antibodies, such as anti-mannan, and molecular tests. With the exception of some molecular methods for rare fungi, the non-cultural assays are usually applied to the diagnosis of invasive aspergillosis, invasive candidiasis and pneumocystosis. The performance of a single test or a combination of tests will be discussed, with particular focus on choosing the most appropriate marker(s) for every specific patient population. Reasons for potential false-positive or false-negative results will be discussed.

Utility of measuring (1,3)-β-d-glucan in cerebrospinal fluid for diagnosis of fungal central nervous system infection

(1-3)-β-d-Glucan (BDG) from cerebrospinal fluid (CSF) is a promising marker for diagnostic and prognostic aid of central nervous system (CNS) fungal infection, but its relationship to serum values has not been studied. Herein, we detected BDG from CSF at levels 2-fold lower than those in serum in patients without evidence of fungal disease but 25-fold higher than those in in serum in noncryptococcal CNS fungal infections. CSF BDG may be a useful biomarker in the evaluation of fungal CNS disease.

Utility of (1-3)-β-D-glucan testing for diagnostics and monitoring response to treatment during the multistate outbreak of fungal meningitis and other infections

BACKGROUND

 The 2012 outbreak of fungal meningitis associated with contaminated methylprednisolone produced by a compounding pharmacy has resulted in >750 infections. An important question facing patients and clinicians is the duration of antifungal therapy. We evaluated (1-3)-β-d-glucan (BDG) as a marker for monitoring response to treatment.

METHODS

 We determined sensitivity and specificity of BDG testing using the Fungitell assay, by testing 41 cerebrospinal fluid (CSF) specimens from confirmed cases of fungal meningitis and 66 negative control CSF specimens. We also assessed whether BDG levels correlate with clinical status by using incident samples from 108 case patients with meningitis and 20 patients with serially collected CSF.

RESULTS

 A cutoff value of 138 pg/mL provided 100% sensitivity and 98% specificity for diagnosis of fungal meningitis in this outbreak. Patients with serially collected CSF were divided into 2 groups: those in whom BDG levels declined with treatment and those in whom BDG remained elevated. Whereas most patients with a decline in CSF BDG had clinical improvement, all 3 patients with continually elevated BDG had poor clinical outcomes (stroke, meningitis relapse, or development of new disease).

CONCLUSIONS

 Our data suggest that measuring BDG in CSF is a highly sensitive test for diagnosis of fungal meningitis in this outbreak. Analysis of BDG levels in serially collected CSF demonstrated that BDG may correlate with clinical response. Routine measurement of BDG in CSF may provide useful adjunctive data for the clinical management of patients with outbreak-associated meningitis.

What can we learn and what do we need to know amidst the iatrogenic outbreak of Exserohilum rostratum meningitis?

The tragedy of the ongoing epidemic of meningitis caused by Exserohilum rostratum brings into focus the epidemiology, risk factors, pathogenesis, diagnosis, and treatment of a multitude of opportunistic mold infections of the central nervous system. Herein we provide our perspective regarding the translational research objectives of this infection that are needed to make an impact on this important healthcare crisis.

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.

(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.

Protective effects of beta glucan and gliclazide on brain tissue and sciatic nerve of diabetic rats induced by streptozosin

There have not been yet enough studies about effects of beta glucan and gliclazide on oxidative stress created by streptozotocin in the brain and sciatic nerve of diabetic rats. The aim of this paper was to investigate the antioxidant effects of gliclazide and beta glucan on oxidative stress and lipid peroxidation created by streptozotosin in brain and sciatic nerve. Total of 42 rats were divided into 6 groups including control, diabetic untreated (DM) (only STZ, diabetic), STZ (DM) + beta glucan, STZ (DM) + gliclazide, only beta glucan treated (no diabetic), and only gliclazide treated (no diabetic). The brain and sciatic nerve tissue samples were analyzed for malondialdehyde (MDA), total oxidant status (TOS), total antioxidant status (TAS), oxidative stress index (OSI), and paraoxonase (PON-1) levels. We found a significant increase in MDA, TOS, and OSI along with a reduction in TAS level, catalase, and PON-1 activities in brain and sciatic nerve of streptozotocin-induced diabetic rats. Also, this study shows that in terms of these parameters both gliclazide and beta glucan have a neuroprotective effect on the brain and sciatic nerve of the streptozotocin-induced diabetic rat. Our conclusion was that gliclazide and beta glucan have antioxidant effects on the brain and sciatic nerve of the streptozotocin-induced diabetic rat.