Diagnosis of invasive aspergillosis by galactomannan antigenemia detection using an enzyme immunoassay

False-positive results of galactomannan assays in patients administered glucose-containing solutions

Galactomannan (GM) is a polysaccharide cell wall component released by Aspergillus spp., and an immunoenzymatic GM assay is used for the diagnosis of invasive pulmonary aspergillosis. We evaluated the cause of strong positivity for GM in patients with no typical signs of aspergillosis. Repeat assays were performed using different instruments and reagent lots, but there were no differences in results among the assays. Patients with strongly positive GM results were investigated. Medication histories revealed that 14 of 23 patients had been administered total parenteral nutrition solution from one manufacturer and 4 patients had been administered dextrose solution from a different manufacturer before being tested. The results of GM assays conducted on samples of dextrose solution and the glucose fraction of the total parenteral nutrition solution were strongly positive, confirming the causes of the false-positive reactions. We hypothesize that a trace amount of GM was introduced into the glucose-containing solutions because glucoamylase, which is necessary for the saccharification step of glucose synthesis, was derived from Aspergillus niger. To enhance patient care and prevent unnecessary antifungal prescriptions, healthcare providers and manufacturers of healthcare products need to be aware of the possibility of false-positive reactions for GM.

Increasing temperature denatures canine IgG reducing its ability to inhibit heartworm antigen detection

BACKGROUND

Immune complexing of target antigen to high affinity host antibody is recognized to impact the sensitivity of commercial heartworm antigen tests. Published information describing the effect of heat on interfering canine host antibodies is lacking. Immune complex dissociation (ICD) by heat treatment of serum for samples initially testing negative for heartworm antigen increases sensitivity of commercial antigen tests, particularly for single sex or low adult infection intensities. In this study the stability and nature of the targeted epitope and mechanism of heat ICD were examined.

METHODS

Canine IgG was isolated using protein-A columns from serum originating from four dogs evaluated after necropsy: one dog with evidence of previously cleared infection and three dogs with confirmed heartworm infections. These dogs were expected to have an excess of antibodies based on negative antigen test and to have no or low antigen optical density, respectively, following heat treatment. Interference of antigen detection on (non-heated) positive serum was evaluated, following 1:1 mixing of antibody/PBS solutions previously heated at 25 °C, 65 °C, 75 °C, 85 °C, 95 °C and 104 °C, compared to positive serum/PBS control measured by optical density using a commercial heartworm antigen ELISA and protein quantification. Live heartworms incubated in media for 72 h provided excretory/secretory antigen for antigen stability studies following heat, endopeptidase digestion and disulfide bond reduction.

RESULTS

Mixing antigen-positive heartworm serum with antibody solutions demonstrated a significant inhibition of antigen detection for antibody solutions previously heated at 25 °C and 65 °C relative to positive serum/PBS control. Antigen detection optical density was restored at or above the control when positive serum was mixed with solutions previously heated at 75 °C, 85 °C, 95 °C and 104 °C. Significant changes occurred in protein levels for antibody solutions heated at 75 °C, 85 °C, 95 °C and 104 °C. Relative stability of antigen from live heartworms in culture was demonstrated following heat, chemical and enzymatic treatment.

CONCLUSIONS

Significant changes in protein levels and antigen binding ability occurred in IgG solutions heated above 65 °C. The findings confirm heat denaturation of antibodies as the suspected mechanism of heat ICD at 104 °C for antigen diagnosis of heartworm. No significant change occurred in antigen detection following heat, chemical or enzymatic digestions supporting a heat-stable linear nature of the epitope.

Invasive Aspergillosis in the Intensive Care Unit

Invasive pulmonary aspergillosis (IPA) is a serious condition resulting in significant mortality and morbidity among patients in intensive care units (ICUs). There is a growing number of at-risk patients for this condition with the increasing use of immunosuppressive therapies. The diagnosis of IPA can be difficult in ICUs, and relies on integration of clinical, radiological, and microbiological features. In this review, we discuss patient populations at risk for IPA, as well as the diagnostic criteria employed. We review the fungal biomarkers used, as well as the challenges in distinguishing colonization with Aspergillus from invasive disease. We also address the growing concern of multidrug-resistant Aspergillosis and review the new and novel therapeutics which are in development to combat this.

Early diagnosis of aspergillosis in asthmatic and rheumatoid arthritis patients by Aspergillus galactomannan antigen assay: a case-control study in Karbala providence

OBJECTIVE

Aspergillosis is an opportunistic systemic infection caused by members of Aspergillus spp. in various parts of the human body. Chronic diseases such as rheumatoid arthritis (RA) and asthma may encourage the development of aspergillosis under specific conditions. Thus, aspergillosis was investigated in patients with RA and asthma based on detection of galactomannan antigen.

METHODS

A case-control study was performed to involve 184 subjects, distributing in four groups: 55 patients with RA, 54 with asthma, 27 with both RA and asthma, and 48 healthy individuals. Serum was collected from involved subjects for detection of human Aspergillus galactomannan by ELISA. The optical density index (ODI) at cutoff <0.5 was used to determine the infection.

RESULTS

Aspergillosis was more frequently diagnosed in females with RA and both RA and asthma in opposite to the males. It also was found in most common in middle-aged subjects. There was no significant difference in measurement of GM between all patient groups and healthy individuals.

CONCLUSION

Aspergillosis can develop in either immunocompetent or immunocompromised individuals. Patients with either RA or RA and asthma are more susceptible to acquired aspergillosis than those with only one disease. Application of GM for diagnosis of aspergillosis may show a nonsignificant results when it uses alone and needs other investigation tests.

Prospective Evaluation of Galactomannan and (1→3) β-d-Glucan Assays as Diagnostic Tools for Invasive Fungal Disease in Children, Adolescents, and Young Adults With Acute Myeloid Leukemia Receiving Fungal Prophylaxis

BACKGROUND

Patients receiving chemotherapy for acute myeloid leukemia (AML) are at high risk for invasive fungal disease (IFD). Diagnosis of IFD is challenging, leading to interest in fungal biomarkers. The objective was to define the utility of surveillance testing with Platelia Aspergillus galactomannan (GM) enzyme immunoassay (EIA) and Fungitell β-d-glucan (BDG) assay in children with AML receiving antifungal prophylaxis.

METHODS

Twice-weekly surveillance blood testing with GM EIA and BDG assay was performed during periods of neutropenia in the context of a randomized trial of children, adolescents, and young adults with AML allocated to fluconazole or caspofungin prophylaxis. Proven or probable IFD was adjudicated using blinded central reviewers. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated for Platelia and Fungitell assays alone and in combination for the outcomes of proven and probable invasive aspergillosis (IA) or invasive candidiasis (IC).

RESULTS

Among 471 patients enrolled, 425 participants (209 fluconazole and 216 caspofungin) contributed ≥1 blood specimen. In total, 6103 specimens were evaluated, with a median of 15 specimens per patient (range 1-43). The NPV was >99% for GM EIA and BDG assay alone and in combination. However, there were no true positive results, resulting in sensitivity and PPV for each assay of 0%.

CONCLUSIONS

The GM EIA and the BDG assay alone or in combination were not successful at detecting IA or IC during periods of neutropenia in children, adolescents, and young adults with AML receiving antifungal prophylaxis. Utilization of these assays for surveillance in this clinical setting should be discouraged.

Imaging features of fungal pneumonia in haematopoietic stem cell transplant patients

Patients who have received haematopoietic stem cell transplantation (HSCT) have a high rate of pulmonary complications, and in this immunosuppressed population, fungal pneumonia is of great concern. Fungal pneumonia can have a similar appearance to non-infectious pulmonary processes in HSCT patients, and radiologists should be familiar with the subtle features that may help to differentiate these disease entities. The focus of this article is on the diagnosis of fungal pneumonia in HSCT patients with an emphasis on radiologists’ roles in establishing the diagnosis of fungal pneumonia and the guidance of clinical management.

Pharmacodynamics of Posaconazole in Experimental Invasive Pulmonary Aspergillosis: Utility of Serum Galactomannan as a Dynamic Endpoint of Antifungal Efficacy

Aspergillus galactomannan antigenemia is an accepted tool for the diagnosis of invasive pulmonary aspergillosis (IPA) in neutropenic patients. Little is known, however, about the utility of this biomarker to assess the efficacy of antifungal therapies. The pharmacokinetics (PK) and pharmacodynamics (PD) of posaconazole in treatment and prophylaxis were investigated in the persistently neutropenic rabbit model of Aspergillus fumigatus IPA at doses between 2 and 20 mg/kg per day. Sparse plasma sampling was used to obtain PK data at steady state, and the serum galactomannan index (GMI), as a dynamic endpoint of antifungal response, was obtained every other day, in addition to conventional outcome parameters including survival and fungal tissue burden. Nonparametric PK/PD model building was performed using the Pmetrics package in R. A one-compartment model with linear elimination best described the PK of posaconazole. The PD effect of posaconazole exposure in plasma on the GMI in serum was best described by dynamic Hill functions reflecting growth and killing of the fungus. Through calculations of the area under the concentration-time curve from 0 to 24 h (AUC_0-24) at steady state, the exposure-response relationship between posaconazole and the GMI for treatment followed a sigmoidal function with an asymptote forming above an AUC_0-24 of 30 mg · h/liter. All prophylactic doses were able to control the fungal burden. A nonparametric population PK/PD model adequately described the effect of posaconazole in prophylaxis and treatment of experimental IPA. An AUC_0-24 greater than 30 mg · h/liter was associated with adequate resolution of the GMI, which well supports previously suggested exposure-response relationships in humans.

Short course of voriconazole therapy as a risk factor for relapse of invasive pulmonary aspergillosis

To investigate associations of the duration of voriconazole treatment and radiological response with relapse of invasive pulmonary aspergillosis (IPA) in immunocompromised patients, we explored the risk factors for IPA relapse after successful initial treatment. All patients with proven or probable IPA who had finished voriconazole treatment between 2005 and 2019 in a tertiary-care hospital were reviewed. IPA relapse was defined as re-diagnosis of proven or probable IPA at the same site within 1 year after treatment termination. Short course of voriconazole treatment was defined as a treatment less than 9 weeks, which is a median of the recommended minimum duration of therapy from the Infectious Disease Society of America. The radiological response was defined as a reduction in IPA burden by more than 50% on chest computed tomography. Of 87 patients who had completed voriconazole treatment, 14 (16.1%) experienced IPA relapse. Multivariable Cox regression identified that short voriconazole treatment duration (adjusted hazard ratio [aHR], 3.7; 95% confidence interval [CI], 1.1–12.3; P = 0.033) and radiological non-response (aHR, 4.6; 95% CI, 1.2–17.5; P = 0.026) were independently associated with relapse of IPA after adjusting for several clinical risk factors. Longer duration of therapy should be considered for those at higher risk of relapse.

Species-specific detection of medically important aspergilli by a loop-mediated isothermal amplification method in chronic pulmonary aspergillosis

Chronic pulmonary aspergillosis (CPA) is a common subtype of pulmonary aspergillosis and a life-threatening disease. However, its diagnosis remains difficult due to the lack of specific clinical features and radiologic findings, as well as the difficulty of isolating Aspergillus spp. We developed a novel species-specific detection method of medically important aspergilli using a loop-mediated isothermal amplification (LAMP) for CPA. Specific LAMP primer sets for Aspergillus fumigatus, Aspergillus flavus, Aspergillus niger, Aspergillus terreus, and Aspergillus nidulans were designed. The use of the LAMP assay was validated using respiratory specimens (CPA cases, n = 21; nonaspergillosis cases, n = 23). A total of 15 cases were positive in the CPA group (A. fumigatus, n = 5; A. flavus, n = 1; A. niger, n = 1; A. terreus, n = 7; A. nidulans, n = 1), but only three in the non-CPA group (A. niger, n = 2; A. terreus n = 1). The sensitivity and specificity of the diagnosis of CPA by the LAMP system were 71.4% and 87.0%, respectively. In conclusion, we developed a species-specific detection approach for five medically important aspergilli using the LAMP method. The system showed high sensitivity and specificity for diagnosis of CPA.

A Simple and Rapid Fungal DNA Isolation Assay Based on ZnO Nanoparticles for the Diagnosis of Invasive Aspergillosis

Invasive aspergillosis (IA) is an important cause of morbidity and mortality among immunocompromised people. Imaging and specimen tests used in the clinical diagnosis of aspergillosis with weak and indistinct defects leads to delay in the treatment of early aspergillosis patients. The developing molecular techniques provide a new method for the aspergillosis diagnosis. However, the existing methods are complex, time-consuming and may even be potentially hazardous. In this study, we developed a simple and rapid Aspergillus fumigatus spores DNA isolation assay using synthesized zinc oxide (ZnO). ZnO nanoparticles were used to take the place of the traditional commercial lysis buffer. The quality and quantity of the extracted DNA were sufficient for further diagnostics with polymerase chain reaction (PCR) analysis. This method offers easy, green, and economic alternative DNA isolation for the diagnosis of invasive aspergillosis.

Why are so many cases of invasive aspergillosis missed?

Invasive aspergillosis (IA) incidence is increasing in several countries like France, and numerous cases are indeed missed and still only diagnosed at autopsy as evidenced by recently published data. Such missed diagnoses are obviously encountered when appropriate diagnostic tools are not available especially in low resource areas or when biologists have not been trained enough in medical mycology (i.e., microscopic examination and culture in most of those areas). Besides logistical issues, which are indeed critical, IA may not be recognized because clinicians failed to consider that risk factors are evolving with the IA burden now observed among patients with chronic lymphoid malignancies or receiving new biotherapies, with diabetes mellitus or liver cirrhosis and/or acute alcoholic hepatitis, with patients from the intensive care unit (ICU) and among patients with some predisposing primary immune deficiencies now reaching the adult's age. This is also the case for human immunodeficiency virus (HIV)-infected patients who failed to meet the classical definitions of IA. From the radiology perspective, new entities of IA have also emerged which absolutely need to be recognized especially bronchial-based-IA among allogeneic stem cell transplant recipients. Finally, from the laboratory side, contribution and limits of indirect blood biomarkers should be integrated to the clinical life in order not to miss IA cases. To conclude, several diagnostic tools should be combined and a constant dialog between laboratory and clinics is crucial to appropriately diagnose IA.

Can Aspergillus fumigatus conidia cause false-positive results in the galactomannan enzyme immunoassay test?

INTRODUCTION

Several factors can cause false-positive results in the galactomannan (GM) test; however, others remain unknown. Presently, the impact of airborne contamination by Aspergillus conidia during enzyme-linked immunosorbent assay (ELISA) remains uninvestigated.

METHODS

We studied 12 A. fumigatus isolates. Fungal conidia were serially diluted and tested for GM detection using the Platelia® Aspergillus enzyme immunoassay (EIA).

RESULTS

The conidia concentration required for an EIA-positive result was 4.8 × 103 (median).

CONCLUSIONS

This is the first study to evaluate the impact of environmental contamination on the Platelia® Aspergillus EIA assay. Only massive contamination can interfere with GM optical readings, suggesting that environmental contamination does not cause false-positive test results.

Detection of invasive pulmonary aspergillosis in critically ill patients by combined use of conventional culture, galactomannan, 1-3-beta-D-glucan and Aspergillus specific nested polymerase chain reaction in a prospective pilot study

Invasive pulmonary aspergillosis (IPA) is an emerging and life-threatening infectious disease in patients admitted to the intensive care unit (ICU). Most diagnostic studies are conducted in hematological patients and results cannot readily be transferred to ICU patients lacking classical host factors. In a multicenter, prospective clinical trial including 44 ICU patients, hematological (n = 14) and non-hematological patients (n = 30), concurrent serum and bronchoalveolar lavage (BAL) samples were analyzed by conventional culture, galactomannan (GM), 1-3-beta-D-glucan (BDG) as well as an Aspergillus specific nested polymerase chain reaction (PCR). Nine patients (20%) had putative IPA according to AspICU classification. GM and PCR showed superior performance in BAL with sensitivity/specificity of 56%/94% and 44%/94% compared to 33%/97% and 11%/94% in serum. Despite better sensitivity of 89%, BDG showed poor specificity of only 31% (BAL) and 26% (serum). Combination of GM and PCR (BAL) with BDG (serum) resulted in 100% sensitivity, but also reduced specificity to 23%. Whereas mean GM levels were significantly higher in hematological patients BDG and PCR did not differ between hematological and non-hematological patients. Under present clinical conditions test combinations integrating both BAL and blood samples are advantageous. BDG might best serve as possible indicator for ruling out IPA.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01695499. First posted: September 28, 2012, last update posted: May 8, 2017.

Prime detection of Dirofilaria immitis: understanding the influence of blocked antigen on heartworm test performance

Detection of circulating antigen of Dirofilaria immitis has been a mainstay of identifying heartworm infection in clinical practice for the past three decades. Several validated commercial antigen tests have very good sensitivity, specificity, and positive predictive values, especially when used in patients for which heartworm infection is likely. In some dogs and cats infected with heartworm, antigen may not be available for detection although present in the patient sample; heat pretreatment of these samples reveals the antigen, changing the false negative to positive. This phenomenon was documented in the literature in the 1980s but subsequently overlooked by the heartworm research community for many years. In this review, we provide a summary of the current understanding of the role of heat reversal in diagnosing heartworm infection. This additional diagnostic step is most important for patients in which heartworm infection is likely, such as dogs or cats in an endemic area with an inconsistent history of heartworm preventive use, or dogs with a prior diagnosis of heartworm infection that were recently treated. To illustrate the concept, we share a summary of results from canine samples tested at the state veterinary diagnostic laboratory in Oklahoma, USA in 2017 by modified Knott test and by commercial antigen test before and after heat treatment of samples; in this sample set, heat treatment changed all D. immitis microfilaria-positive but antigen-negative samples to antigen-positive. Pet dogs with a history of consistent preventive use are unlikely to become positive with heat pretreatment; for that reason, routine pretreatment of all samples tested in a veterinary practice is not recommended. We also review known causes of false negative and false positive results on heartworm antigen tests that, although uncommon, can complicate accurate diagnosis in individual patients. Together, this review provides a primer to aid understanding of strategies that can enhance accurate diagnosis of heartworm infection in veterinary practice and clinical research.

Novel mouse monoclonal antibodies specifically recognize Aspergillus fumigatus galactomannan

A panel of specific monoclonal antibodies (mAbs) against synthetic pentasaccharide β-D-Galf-(1→5)-[β-D-Galf-(1→5)]₃-α-D-Manp, structurally related to Aspergillus fumigatus galactomannan, was generated using mice immunized with synthetic pentasaccharide-BSA conjugate and by hybridoma technology. Two selected mAbs, 7B8 and 8G4, could bind with the initial pentasaccharide with affinity constants of approximately 5.3 nM and 6.4 nM, respectively, based on surface plasmon resonance-based biosensor assay. The glycoarray, built from a series of synthetic oligosaccharide derivatives representing different galactomannan fragments, demonstrated that mAb 8G4 could effectively recognize the parental pentasaccharide while mAb 7B8 recognizes its constituting trisaccharide parts. Immunofluorescence studies showed that both 7B8 and 8G4 could stain A. fumigatus cells in culture efficiently, but not the mutant strain lacking galactomannan. In addition, confocal microscopy demonstrated that Candida albicans, Bifidobacterium longum, Lactobacillus plantarum, and numerous gram-positive and gram-negative bacteria were not labeled by mAbs 7B8 and 8G4. The generated mAbs can be considered promising for the development of a new specific enzyme-linked assay for detection of A. fumigatus, which is highly demanded for medical and environmental controls.

Evaluation of Two Commercial Real-Time PCR Kits for Aspergillus DNA Detection in Bronchoalveolar Lavage Fluid in Patients with Invasive Pulmonary Aspergillosis

Invasive pulmonary aspergillosis (IPA) is a common complication of immunosuppression. Rapid diagnosis using molecular techniques is essential to improve patient survival. PCR techniques are promising in enhancing Aspergillus detection in blood and respiratory samples. We evaluate for the first time the performances of two commercial real-time PCR kits, the A. fumigatus Bio-Evolution and the MycoGENIE A. fumigatus for the detection of A. fumigatus DNA in bronchoalveolar lavage (BAL) from patients with and without IPA. Seventy-three BAL samples were included. Thirty-one of them corresponded to patients with probable IPA, 11 to patients with possible IPA, and 31 to patients without aspergillosis, according to the 2008 European Organization for Research and Treatment of Cancer/Mycoses Study Group criteria. In the probable IPA group, A. fumigatus Bio-Evolution and the MycoGENIE A. fumigatus real-time PCR kits showed a specificity of 100% and a sensitivity of 81% and 71%, respectively. The A. fumigatus Bio-Evolution detected Aspergillus DNA in the 14 BAL samples with a positive Aspergillus culture result, whereas the MycoGENIE A. fumigatus PCR result was positive only for 12. In the possible IPA group, there were no positive real-time PCR or positive Aspergillus culture results. For the patients without aspergillosis, no positive result was observed for real-time PCR kit, despite the presence of various other non-Aspergillus pathogens in this group. Our study demonstrates an excellent specificity and a good sensitivity of A. fumigatus DNA detection in BAL samples with both kits.

Impact of heat treatment on antigen detection in sera of Angiostrongylus vasorum infected dogs

Background

In the last decade serological tests for detection of circulating Angiostrongylus vasorum antigen and specific antibodies have been developed and adopted for individual diagnosis and epidemiological studies in dogs. Although confirmed positive at necropsy, antigen detection was not possible in single experimentally, as well as naturally infected dogs, possibly due to immune complex formation. The aim of this study was to evaluate the effect of heat treatment on detection of A. vasorum antigen in sera of experimentally (n = 21, 119 follow-up sera) and naturally (n = 18) infected animals. In addition, sera of dogs showing clinical signs consistent with angiostrongylosis (n = 10), of randomly selected dogs (n = 58) and of dogs with other parasitic infections (n = 15) were evaluated. Sera were subjected to heat treatment at 100 °C after addition of 0.5 M EDTA (dilution 1:5) and tested with ELISAs for detection of circulating A. vasorum antigen before and after treatment.

Results

Between 5 and 11 weeks post-inoculation (wpi) the percentage of positive untreated samples (experimentally infected dogs) increased over time from 33.3 to 90%. Single samples were still negative between 12 and 15 wpi. Overall, between 5 and 15 wpi, 50.6% (45/89) of the available samples were seropositive. From 3 to 6 wpi EDTA/heat treatment caused a change in 8/34 (23.5%) of the samples, with most (n = 6, 17.6%) converting from positive to negative. In contrast, from 7 to 10 wpi, treatment induced a change in 19/52 (36.5%) samples, with all but one converting from negative to positive. Thirteen of 18 naturally infected dogs were antigen positive before and 15 after EDTA/heat treatment, respectively. Untreated samples of 3 dogs with suspected angiostrongylosis were antigen positive, of which only one remained positive after EDTA/heat treatment. One of 58 untreated random samples was antigen positive; this sample became negative after treatment, while another turned positive. One of 15 dogs infected with other parasites than A. vasorum was positive before but negative after treatment.

Conclusion

Although heat treatment improves A. vasorum antigen detection between 7 and 10 wpi by immune complex disruption, we do not recommend systematic pretreating sera because of reduced antigen detection between 3 and 6 wpi and impairment of antibody detection, if performed contemporaneously.

2016 guideline strategies for the use of antifungal agents in patients with hematological malignancies or hematopoietic stem cell transplantation recipients in Taiwan

The Infectious Diseases Society of Taiwan (IDST), the Hematology Society of Taiwan, the Taiwan Society of Blood and Marrow Transplantation, Medical Foundation in Memory of Dr. Deh-Lin Cheng, Foundation of Professor Wei-Chuan Hsieh for Infectious Diseases Research and Education, and CY Lee's Research Foundation for Pediatric Infectious Diseases and Vaccines cooperatively published this guideline for the use of antifungal agents in hematological patients with invasive fungal diseases (IFDs) in Taiwan. The guideline is the first one endorsed by IDST focusing on selection of antifungal strategies, including prophylaxis, empirical (or symptom-driven) and pre-emptive (or diagnostic-driven) strategy. We suggest a risk-adapted dynamic strategy and provide an algorithm to facilitate decision making in population level as well as for individual patient. Risk assessment and management accordingly is explicitly emphasized. In addition, we highlight the importance of diagnosis in each antifungal strategy among five elements of the antimicrobial stewardship (diagnosis, drug, dose, de-escalation and duration). The rationale, purpose, and key recommendations for the choice of antifungal strategy are summarized, with concise review of international guidelines or recommendation, key original articles and local epidemiology reports. We point out the interaction and influence between elements of recommendations and limitation of and gap between evidences and daily practice. The guideline balances the quality of evidence and feasibility of recommendation in clinical practice. Finally, this version introduces the concept of health economics and provides data translated from local disease burdens. All these contents hopefully facilitate transparency and accountability in medical decision-making, improvements in clinical care and health outcomes, and appropriateness of medical resource allocation.

Fungal Pneumonia in Patients with Hematologic Malignancy and Hematopoietic Stem Cell Transplantation

Fungal pneumonias cause unacceptable morbidity among patients with hematologic malignancies (HM) and recipients of hematopoietic stem cell transplantation (HSCT). The high incidence of fungal pneumonias in HM/HSCT populations arises from their frequently severe, complex, and persistent immune dysfunction caused by the underlying disease and its treatment. The cytopenias, treatment toxicities, and other immune derangements that make patients susceptible to fungal pneumonia frequently complicate its diagnosis and increase the intensity and duration of antifungal therapy. This article addresses the host factors that contribute to susceptibility, summarizes diagnostic recommendations, and reviews current guidelines for management of fungal pneumonia in patients with HM/HSCT.

Evaluating the use of PCR for diagnosing invasive aspergillosis

INTRODUCTION

Aspergillus species, primarily Aspergillus fumigatus, are still the most emerging fungal pathogens. Within recent years, novel molecular methods have been developed to improve the diagnosis of life-threatening invasive aspergillosis in high risk patients. Especially patients with malignant hematological diseases undergoing intensive chemotherapy are at risk and mortality rates are exceptionally high, in part due to difficulties and delays in establishing a microbiologic diagnosis. Early diagnosis and treatment are crucial for an adequate therapeutical management, but, however, are hardly achieved in the clinical setting because most of the current conventional diagnostic tools either lack specificity or acceptable sensitivity at the critical early phase of the infection. Areas covered: To review the clinical value, advantages and problems as well as drawbacks of molecular approaches, especially polymerase chain reaction (PCR)-based assays to detect genomic DNA of Aspergillus species in clinical samples of immunocompromised, especially hematological patients at high risk for IA, a comprehensive review of the literature was performed and expert opinion was expressed. Expert commentary: The results of numerous attempts to diagnose invasive aspergillosis by PCR-based detection of fungal genome in clinical samples highlight the potential of the PCR technique to improve early diagnosis of invasive aspergillosis in patients with hematological malignancies during intensive antineoplastic treatment, combined with imaging surveillance and serologic diagnostic tools. Further comparative validation of reliable assays in prospective multicenter studies is mandatory and urgently needed in order to establish a harmonization and standardization, so that 'gold standard assays' may be incorporated into diagnostic and therapeutic algorithms that improve the prognosis of patients with life-threatening infections caused by Aspergillus species.

A prospective study of fungal biomarkers to improve management of invasive fungal diseases in a mixed specialty critical care unit

PURPOSE

The diagnosis of invasive fungal diseases (IFD) in critical care patients (CrCP) is difficult. The study investigated the performance of a set of biomarkers for diagnosis of IFD in a mixed specialty critical care unit (CrCU).

METHODS

A prospective observational study in patients receiving critical care for ≥7days was performed. Serum samples were tested for the presence of: (1-3) - β-d-glucan (BDG), galactomannan (GM), and Aspergillus fumigatus DNA. GM antigen detection was also performed on bronchoalveolar lavage (BAL) samples. The patients were classified using published definitions for IFD and a diagnostic algorithm for invasive pulmonary aspergillosis. Performance parameters of the assays were determined.

RESULTS

In patients with proven and probable IFD, the sensitivity, specificity, PPV and NPV of a single positive BDG were 63%, 83%, 65% and 83% respectively. Specificity increased to 86% with 2 consecutive positive results. The mean BDG value of patients with proven and probable IFD was significantly higher compared to those with fungal colonization and no IFD (p value<0.0001).

CONCLUSION

New diagnostic criteria which incorporate these biomarkers, in particular BDG, and host factors unique to critical care patients should enhance diagnosis of IFD and positively impact antifungal stewardship programs.

Preemptive Antifungal Therapy for Febrile Neutropenic Hematological Malignancy Patients in China

Background

The aim of this study was to evaluate the efficiency, adverse effects, and pharmacoeconomic impact of empirical and preemptive antifungal therapy for febrile neutropenic hematological malignancy patients in China.

Material/Methods

Patients with febrile neutropenia during hematological malignancy were randomly divided into an empirical group and a preemptive group. The preemptive antifungal treatment was initiated if patient status was confirmed by clinical manifestation, imaging diagnosis, 1-3-β-D glucan(G) testing, and galactomannan (GM) test. The treatment was ended 2 weeks later if the patient was recovered from neutropenia. Voriconazole was used as the first-line medicine. All patients received intravenous administration of voriconazole every 12 h, with an initiating dose of 400 mg, then the dose was reduced to 200 mg.

Results

The overall survival rate was 97.1% and 94.6% in the empirical group and preemptive group, respectively, with no significant difference observed (χ²=1.051, P=0.305). However, the occurrence rate of invasive fungal disease (IFD) in the preemptive group was 9.2% vs. 2.2% in the empirical group. Moreover, the mortality rate due to IFD was 0.7% and 2.3% for the empirical group and preemptive group, respectively. The average duration and cost of preemptive antifungal therapy were 13.8±4.7 days and 8379.00±2253.00 RMB, respectively, which were lower than for empirical therapy. However, no significant differences were observed for incidence of adverse effects and hospital stay between the 2 groups.

Conclusions

Preemptive antifungal therapy for patients with febrile neutropenic hematological malignancy demonstrated a similar survival rate as with empirical therapy but is economically favorable in a Chinese population.

Fungal Endocarditis: Update on Diagnosis and Management

Fungal endocarditis is an extremely debilitating disease associated with high morbidity and mortality. Candida spp. are the most common isolated organisms in fungal endocarditis. It is most prevalent in patients who are immunosuppressed and intravenous drug users. Most patients present with constitutional symptoms, which are indistinguishable from bacterial endocarditis, hence a high index of suspicion is required for pursuing diagnosis. Diagnosis of fungal endocarditis can be very challenging: most of the time, blood cultures are negative or take a long time to yield growth. Fungal endocarditis mandates an aggressive treatment strategy. A medical and surgical combined approach is the cornerstone of therapy.

Diagnostic Values and Limitations of (1,3)-β-D-Glucans and Galactomannan Assays for Invasive Fungal Infection in Patients Admitted to Pediatric Intensive Care Unit

The relationship among (1,3)-β-D-glucans (BG), galactomannan (GM), and the risk of developing invasive fungal infections (IFI) has been observed in adult ICU and in children with hematological malignancies. Only scant data evaluated the value of BG/GM assays for diagnosis of IFI in patients with nonhematological diseases in pediatric intensive care unit (PICU). In this study, we assessed the diagnostic value of these markers for IFI in PICU. The records of 230 patients were retrospectively evaluated. Out of 117 patients (7 proven, 23 probable, and 87 cases without evidence of IFI) performed GM and BG assays. The results showed many factors were associated with false-positive test results. Patients who aged over 3 years had higher levels of GM and BG than younger infants. The levels of BG were higher in subjects with dairy, human blood products, antibiotics, and corticosteroids therapy than in cases without these treatments. Unlike BG assay, GM assay was less susceptible to above-mentioned factors expect blood products. The levels of BG and GM in IFI cases were dramatically higher than in controls. The diagnostic performance of these assays showed that GM assay had better results when compared with BG assay. On the whole, negative predictive value in both GM and BG assays was dramatically higher than other diagnostic parameters. In conclusion, BG assay was highly susceptible to many factors, and GM assay could be useful for diagnosis of IFI for its high sensitivity, but the over benefit of this assay limited in its inadequate specificity. The comparative advantage of BG and BG assays lied in excluding IFI in non-hematological PICU patients.

Chronic Pulmonary Aspergillosis-Where Are We? and Where Are We Going?

Chronic pulmonary aspergillosis (CPA) is estimated to affect 3 million people worldwide making it an under recognised, but significant health problem across the globe, conferring significant morbidity and mortality. With variable disease forms, high levels of associated respiratory co-morbidity, limited therapeutic options and prolonged treatment strategies, CPA is a challenging disease for both patients and healthcare professionals. CPA can mimic smear-negative tuberculosis (TB), pulmonary histoplasmosis or coccidioidomycosis. Cultures for Aspergillus are usually negative, however, the detection of Aspergillus IgG is a simple and sensitive test widely used in diagnosis. When a fungal ball/aspergilloma is visible radiologically, the diagnosis has been made late. Sometimes weight loss and fatigue are predominant symptoms; pyrexia is rare. Despite the efforts of the mycology community, and significant strides being taken in optimising the care of these patients, much remains to be learnt about this patient population, the disease itself and the best use of available therapies, with the development of new therapies being a key priority. Here, current knowledge and practices are reviewed, and areas of research priority highlighted.

Invasive pulmonary mycosis due to Chaetomium globosum with false-positive galactomannan test: a case report and literature review

In this case, the authors report Chaetomium globosum as a cause of invasive pulmonary infection in a patient with Wegener's granulomatosis. Fungal hyphae (KOH and Calcofluor) were seen on direct microscopy of lung biopsy sample and bronchoalveolar lavage (BAL) sample. C. globosum isolated on culture clinched the diagnosis of invasive pulmonary infection by Chaetomium spp. A positive galactomannan of serum and BAL was repeatedly seen and was utilised for follow-up and as prognostic marker in patient management. The patient was successfully treated with liposomal amphotericin B followed by voriconazole. All the Chaetomium infections reported till date since 1980 are reviewed. Chaetomium spp. with its unique ecology has a hidden clinical potential to cause invasive mould infections.

Identification of invasive fungal diseases in immunocompromised patients by combining an Aspergillus specific PCR with a multifungal DNA-microarray from primary clinical samples

The increasing incidence of invasive fungal diseases (IFD), most of all invasive aspergillosis (IA) in immunocompromised patients emphasises the need to improve the diagnostic tools for detection of fungal pathogens. We investigated the diagnostic performance of a multifungal DNA-microarray detecting 15 different fungi [Aspergillus, Candida, Fusarium, Mucor, Rhizopus, Scedosporium and Trichosporon species (spp.)] in addition to an Aspergillus specific polymerase chain reaction (PCR) assay. Biopsies, bronchoalveolar lavage and peripheral blood samples of 133 immunocompromised patients (pts) were investigated by a multifungal DNA-microarray as well as a nested Aspergillus specific PCR assay. Patients had proven (n = 18), probable (n = 29), possible (n = 48) and no IFD (n = 38) and were mostly under antifungal therapy at the time of sampling. The results were compared to culture, histopathology, imaging and serology, respectively. For the non-Aspergillus IFD the microarray analysis yielded in all samples a sensitivity of 64% and a specificity of 80%. Best results for the detection of all IFD were achieved by combining DNA-microarray and Aspergillus specific PCR in biopsy samples (sensitivity 79%; specificity 71%). The molecular assays in combination identify genomic DNA of fungal pathogens and may improve identification of causative pathogens of IFD and help overcoming the diagnostic uncertainty of culture and/or histopathology findings, even during antifungal therapy.

Biomarkers for invasive aspergillosis: the challenges continue

The incidence of invasive aspergillosis (IA), an opportunistic infection in immunocompromised individuals, is rising, but its early diagnosis remains challenging and treatment options are limited. Hence there is an urgent need to improve existing diagnostic procedures as well as develop novel approaches. The clinical usefulness of galactomannan and β-d-glucan, widely used assays detecting cell-wall antigens of Aspergillus, is unclear and depends on clinicians' awareness of their practical limitations. This leaves room for new methods that utilise genomic, proteomic and metabolomics approaches as well as novel detection procedures, for example point-of-care lateral-flow devices. Each of these strategies has its own limitations and it is likely that a combination of methods will be required to achieve optimal performance for the diagnosis of IA and subsequent appropriate patient management.

Development and validation of an HPLC-MS/MS method for the early diagnosis of aspergillosis

Invasive aspergillosis is an opportunistic infection that is mainly caused by Aspergillus fumigatus, which is known to produce several secondary metabolites, including gliotoxin, the most abundant metabolite produced during hyphal growth. The diagnosis of invasive aspergillosis is often made late in the infection because of the lack of reliable and feasible diagnostic techniques; therefore, early detection is critical to begin treatment and avoid more serious complications. The present work reports the development and validation of an HPLC-MS/MS method for the detection of gliotoxin in the serum of patients with suspected aspergillosis. Chromatographic separation was achieved using an XBridge C18 column (150×2.1 mm id; 5 mm particle size) maintained at 25°C with the corresponding guard column (XBridge C18, 10×2.1 mm id, 5 mm particle size). The mobile phase was composed of a gradient of water and acetonitrile/water (95∶5 v/v), both containing 1 mM ammonium formate with a flow rate of 0.45 mL min⁻¹. Data from the validation studies demonstrate that this new method is highly sensitive, selective, linear, precise, accurate and free from matrix interference. The developed method was successfully applied to samples from patients suspected of having aspergillosis. Therefore, the developed method has considerable potential as a diagnostic technique for aspergillosis.

Pre-treatment with heat facilitates detection of antigen of Dirofilaria immitis in canine samples

Diagnosis of Dirofilaria immitis infection in dogs is largely dependent on detection of antigen in canine serum, plasma, or whole blood, but antigen may be bound in immune complexes and thus not detected. To develop a model for antigen blocking, we mixed serum from a microfilaremic, antigen-positive dog with that of a hypergammaglobulinemic dog not currently infected with D. immitis and converted the positive sample to antigen-negative; detection of antigen was restored when the mixed sample was heat-treated, presumably due to disruption of antigen/antibody complexes. A blood sample was also evaluated from a dog that was microfilaremic and for which microfilariae were identified as D. immitis by morphologic examination. Antigen of D. immitis was not detected in this sample prior to heating but the sample was strongly positive after heat treatment of whole blood. Taken together, our results indicate that blood samples from some dogs may contain factors that inhibit detection of antigen of D. immitis, and that heat treatment of these samples prior to testing could improve the sensitivity of these assays in some patients.

Heat treatment prior to testing allows detection of antigen of Dirofilaria immitis in feline serum

Background

Diagnosis of Dirofilaria immitis infection in cats is complicated by the difficulty associated with reliable detection of antigen in feline blood and serum samples.

Methods

To determine if antigen-antibody complex formation may interfere with detection of antigen in feline samples, we evaluated the performance of four different commercially available heartworm tests using serum samples from six cats experimentally infected with D. immitis and confirmed to harbor a low number of adult worms (mean = 2.0). Sera collected 168 (n = 6), 196 (n = 6), and 224 (n = 6) days post infection were tested both directly and following heat treatment.

Results

Antigen was detected in serum samples from 0 or 1 of 6 infected cats using the assays according to manufacturer’s directions, but after heat treatment of serum samples, as many as 5 of 6 cats had detectable antigen 6–8 months post infection. Antibodies to D. immitis were detected in all six infected cats by commercial in-clinic assay and at a reference laboratory.

Conclusions

These results indicate that heat treatment of samples prior to testing can improve the sensitivity of antigen assays in feline patients, supporting more accurate diagnosis of this infection in cats. Surveys conducted by antigen testing without prior heat treatment of samples likely underestimate the true prevalence of infection in cats.

Neutropenic fever and sepsis: evaluation and management

Neutropenia remains the predominant predisposing factor for infection in most cancer patients. Bacterial and fungal infections are common in this setting. Not all neutropenic patients have the same risk of developing severe infection or serious medical complications. Although all patients with neutropenia and fever should receive prompt, empiric antibiotic therapy, low-risk patients can be effectively managed without hospitalization-often with the administration of oral antibiotics. Other patients need hospital-based therapy. The emergence of resistant microorganisms has become a significant problem in neutropenic patients. Frequent epidemiologic surveys to detect the emergence of resistant organisms are recommended. Antibiotic stewardship and Infection Control Programs are important tools in combating resistant organisms.

Proteomic demonstration of the recurrent presence of inter-alpha-inhibitor H4 heavy-chain during aspergillosis induced in an animal model

Invasive pulmonary aspergillosis remains a matter of great concern in oncology/haematology, intensive care units and organ transplantation departments. Despite the availability of various diagnostic tools with attractive features, new markers of infection are required for better medical care. We therefore looked for potential pulmonary biomarkers of aspergillosis, by carrying out two-dimensional (2D) gel electrophoresis comparing the proteomes of bronchial-alveolar lavage fluids (BALF) from infected rats and from control rats presenting non-specific inflammation, both immunocompromised. A bioinformatic analysis of the 2D-maps revealed significant differences in the abundance of 20 protein spots (ANOVA P-value<0.01; q-value<0.03; power>0.8). One of these proteins, identified by mass spectrometry, was considered of potential interest: inter-alpha-inhibitor H4 heavy-chain (ITIH4), characterised for the first time in this infectious context. Western blotting confirmed its overabundance in all infected BALF, particularly at early stages of murine aspergillosis. Further investigations were carried on rat serum, and confirmed that ITIH4 levels increased during experimental aspergillosis. Preliminary results in human samples strengthened this trend. To our knowledge, this is the first description of the involvement of ITIH4 in aspergillosis.

Detection of invasive aspergillosis in bone marrow transplant recipients using real-time PCR

Objective:

The invasive aspergillosis (IA) is a serious opportunistic infection caused by various species of Aspergillus in immunocompromised individuals. Basically, rapid and early diagnosis prevents IA progression. In this study we performed a Real Time PCR/ Fluorescence Resonance Energy Transfer (FRET) for diagnosis of IA in hematologic malignancies and bone marrow transplant recipients.

Materials and Methods:

Sixty two patients with hematologic malignancies and marrow transplant recipients were evaluated for IA in Sari and Tehran from 2009 to 2010. The primer and hybridization probe were designed to amplify the specific sequence of 18S rRNA genes using Light Cycler system and FRET. Galactomannan (GM) assay was performed on serums which obtained from selected patients using the Platelia Aspergillus kit.

Results:

According to the criteria defined by the European Organization for Research and Treatment of Cancer and Mycoses Study Group (EORTC/MSG) for IA, 18 (29%) patients out of 62 patients were stratified into probable and possible groups. The female-to-male ratio was 1:2; the mean age of the patients was 36 years. The most common malignancies in these patients were acute lymphoblastic leukemia (38.9%). The minimum detection limit was 10 conidia (10¹ CFU/ml) equivalents (100 fg) per PCR reaction. GM assay was positive in 20.9% and real-time PCR probe set assay were positive in 17.7% patients who had clinical signs and host factor according to the mentioned criteria.

Conclusion:

Using the Real-Time PCR/FRET assay in whole blood specimens seems to be a promising method for diagnosis of IA, especially when used in combination with the GM detection test.