Multicenter evaluation of a lateral-flow device test for diagnosing invasive pulmonary aspergillosis in ICU patients

Immunoproteomics of Aspergillus for the development of biomarkers and immunotherapies

Filamentous fungi of the genus Aspergillus play significant roles as pathogens causing superficial and invasive infections as well as allergic reactions in humans. Particularly invasive mycoses caused by Aspergillus species are characterized by high mortality rates due to difficult diagnosis and insufficient antifungal therapy. The application of immunoproteomic approaches has a great potential to identify new targets for the diagnosis, therapy, and vaccine development of diseases caused by Aspergillus species. Serological proteome analyses (SERPA) that combine 2D electrophoresis with Western blotting are still one of the most popular techniques for the identification of antigenic proteins. However, recently a growing number of approaches have been developed to identify proteins, which either provoke an antibody response or which represent targets of T-cell immunity in patients with allergy or fungal infections. Here, we review advances in the studies of immune responses against pathogenic Aspergilli as well as the current status of diagnosis and immunotherapy of Aspergillus infections.

Aspergillosis in Chronic Granulomatous Disease

Patients with chronic granulomatous disease (CGD) have the highest life-time incidence of invasive aspergillosis and despite the availability of antifungal prophylaxis, infections by Aspergillus species remain the single most common infectious cause of death in CGD. Recent developments in curative treatment options, such as haematopoietic stem cell transplantation, will change the prevalence of infectious complications including invasive aspergillosis in CGD patients. However, invasive aspergillosis in a previously healthy host is often the first presenting feature of this primary immunodeficiency. Recognizing the characteristic clinical presentation and understanding how to diagnose and treat invasive aspergillosis in CGD is of utmost relevance to improve clinical outcomes. Significant differences exist in fungal epidemiology, clinical signs and symptoms, and the usefulness of non-culture based diagnostic tools between the CGD host and neutropenic patients, reflecting underlying differences in the pathogenesis of invasive aspergillosis shaped by the nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase deficiency.

Detection of Aspergillus fumigatus in Blood Samples from Critically Ill Patients in Intensive Care Units by Use of the SeptiFast Assay

We retrospectively analyzed the performance and relevance of the SeptiFast assay in detecting Aspergillus fumigatus DNA in whole blood samples from 38 critically ill intensive care unit (ICU) patients with probable or proven invasive aspergillosis (IA) and 100 ICU patients without IA. The assay exhibited 66% sensitivity, 98% specificity, a 93% positive predictive value, and an 88% negative predictive value. A. fumigatus DNAemia was associated with poor outcome.

Point of Care Testing for the Diagnosis of Fungal Infections: Are We There Yet?

Diagnostic tools for invasive fungal infections have continuously improved within the last decades. Nowadays, cultural methods, antigen testing, and molecular tests, such as polymerase chain reaction, are widely used. These methods, however, are accompanied with different limitations as various availability, various turnaround time or high costs. A new generation of point-of-care test has shown promising results in various studies and may overcome some of these limitations. We therefore reviewed the literature for the most promising new point-of-care tests for invasive aspergillosis (Aspergillus-specific lateral-flow device test, Aspergillus proximity ligation antigen assay), cryptococcosis (cryptococcal lateral-flow assay), and for histoplasmosis (loop-mediated isothermal amplification assay).

The standard of care of patients with ARDS: ventilatory settings and rescue therapies for refractory hypoxemia

Purpose

Severe ARDS is often associated with refractory hypoxemia, and early identification and treatment of hypoxemia is mandatory. For the management of severe ARDS ventilator settings, positioning therapy, infection control, and supportive measures are essential to improve survival.

Methods and results

A precise definition of life-threating hypoxemia is not identified. Typical clinical determinations are: arterial partial pressure of oxygen < 60 mmHg and/or arterial oxygenation < 88 % and/or the ratio of PaO₂/FIO₂ < 100. For mechanical ventilation specific settings are recommended: limitation of tidal volume (6 ml/kg predicted body weight), adequate high PEEP (>12 cmH₂O), a recruitment manoeuvre in special situations, and a ‘balanced’ respiratory rate (20-30/min). Individual bedside methods to guide PEEP/recruitment (e.g., transpulmonary pressure) are not (yet) available. Prone positioning [early (≤ 48 hrs after onset of severe ARDS) and prolonged (repetition of 16-hr-sessions)] improves survival. An advanced infection management/control includes early diagnosis of bacterial, atypical, viral and fungal specimen (blood culture, bronchoalveolar lavage), and of infection sources by CT scan, followed by administration of broad-spectrum anti-infectives. Neuromuscular blockage (Cisatracurium ≤ 48 hrs after onset of ARDS), as well as an adequate sedation strategy (score guided) is an important supportive therapy. A negative fluid balance is associated with improved lung function and the use of hemofiltration might be indicated for specific indications.

Conclusions

A specific standard of care is required for the management of severe ARDS with refractory hypoxemia.

Diagnostics and susceptibility testing in Aspergillus

Invasive aspergillosis is a major cause of morbidity and mortality in immunosuppressed patients. Early diagnosis and correct antifungal treatment have a direct impact on patient survival. A number of newer diagnostic procedures have been developed as alternatives to conventional microbiological methods. The detection of fungal components, largely antigens and DNA, are used in clinical laboratories to diagnose invasive aspergillosis. Other rapid diagnostic tests have been recently developed with promising results. However, antifungal resistance is becoming an emerging problem. The detection of this resistance is important to administer the proper antifungal agent. This text reviews the novelties on new diagnostics Aspergillus spp.

PROCEDURES

Intrinsic antifungal resistance and mechanisms of secondary resistance to triazoles in A. fumigatus are also reviewed.

Diagnostic of Fungal Infections Related to Biofilms

Fungal biofilm-related infections, most notably those caused by the Candida and Aspergillus genera, need to be diagnosed accurately and rapidly to avoid often unfavorable outcomes. Despite diagnosis of these infections is still based on the traditional histopathology and culture, the use of newer, rapid methods has enormously enhanced the diagnostic capability of a modern clinical mycology laboratory. Thus, while accurate species-level identification of fungal isolates can be achieved with turnaround times considerably shortened, nucleic acid-based or antigen-based detection methods can be considered useful adjuncts for the diagnosis of invasive forms of candidiasis and aspergillosis. Furthermore, simple, reproducible, and fast methods have been developed to quantify biofilm production by fungal isolates in vitro. In this end, isolates can be categorized as low, moderate, or high biofilm-forming, and this categorization may reflect their differential response to the conventional antifungal therapy. By means of drug susceptibility testing performed on fungal biofilm-growing isolates, it is now possible to evaluate not only the activity of conventional antifungal agents, but also of novel anti-biofilm agents. Despite this, future diagnostic methods need to target specific biofilm components/molecules, in order to provide a direct proof of the presence of this growth phenotype on the site of infection. In the meantime, our knowledge of the processes underlying the adaptive drug resistance within the biofilm has put into evidence biofilm-specific molecules that could be potentially helpful as therapeutic targets. Surely, the successful management of clinically relevant fungal biofilms will rely upon the advancement and/or refinement of these approaches.

Prognostic potential of 1,3-beta-d-glucan levels in bronchoalveolar lavage fluid samples

OBJECTIVES

The objective of this study was to investigate the prognostic potential of 1,3-beta-d-glucan (BDG) testing in bronchoalveolar lavage fluid (BALF) samples.

METHODS

A total of 300 BALF samples from 252 patients were investigated for BDG (Fungitell(®) assay). Prognostic potential of BALF BDG was evaluated by using: i.) Kaplan-Meier analysis, and ii.) multivariable Cox hazard regression analyses.

RESULTS

BALF BDG levels were found to be significantly higher in samples with Candida spp. colonization (p < 0.001). A total of 61/252 patients (24.2%) died within 90-days of BALF sampling (18.1% of patients with BALF BDG <200 pg/mL, 32.4% with BALF BDG ≥200 pg/mL). Kaplan-Meier analysis revealed that overall cumulative 90-day mortality was significantly higher in those with BALF BDG levels ≥200 pg/mL when compared to those with levels <200 pg/mL (log-rank p = 0.006, Breslow p = 0.005 and Tarone-Ware p = 0.005). The multivariable Cox regression analysis showed that BALF BDG levels were a strong predictor of 90-day overall mortality, with a hazard ratio of 1.048 (per 100 pg/mL increase of BALF BDG).

CONCLUSION

False positive BALF BDG results in the presence of Candida spp. colonization of the lower respiratory tract may explain the limited diagnostic potential of BALF BDG testing. In contrast, prognostic potential of BALF BDG may be promising.

Influence of mould-active antifungal treatment on the performance of the Aspergillus-specific bronchoalveolar lavage fluid lateral-flow device test

The effect of mould-active antifungal (AF) therapy/prophylaxis on the performance of the Aspergillus-specific lateral-flow device (LFD) test for diagnosing invasive pulmonary aspergillosis (IPA) was evaluated. This was a retrospective analysis of patients diagnosed with probable or proven IPA (according to revised EORTC/MSG criteria) at the Medical University of Graz (Austria) and the University Hospital of Mannheim (Germany) between February 2011 and December 2014. In total, 60 patients with 63 bronchoalveolar lavage fluid (BALF) samples were included in the analysis. Patient charts were reviewed regarding AF treatment at the time of bronchoscopy, and the influence of AFs on the performance of the LFD and BALF galactomannan (GM) ELISA results was calculated. Overall, 54 patients (57 BALF samples) had probable IPA and 6 patients (6 samples) had proven IPA. In 21/63 samples (33%) (from 19 patients), systemic mould-active AFs had been initiated before bronchoscopy. Of 63 BALF samples, 16 (25%) yielded a false-negative LFD result. The sensitivity of the LFD for probable/proven IPA was significantly lower in those receiving mould-active AFs compared with those without (52% vs. 86%; P=0.006). Similar results were found for BALF GM, with sensitivities decreasing under systemic AFs (71% vs. 95%, P=0.013 with the 0.5 ODI cut-off; 52% vs. 81%, P=0.036 with the 1.0 cut-off). These results suggest that the sensitivity of the BALF LFD and BALF GM assays may be reduced in the presence of mould-active AF treatment. Negative results in patients on AFs should therefore be interpreted with caution.