Surveillance of Aspergillus galactomannan antigenemia for invasive aspergillosis by enzyme-linked immunosorbent assay in neutropenic patients treated for hematological malignancies

Diagnosis of invasive fungal infections: challenges and recent developments

BACKGROUND

The global burden of invasive fungal infections (IFIs) has shown an upsurge in recent years due to the higher load of immunocompromised patients suffering from various diseases. The role of early and accurate diagnosis in the aggressive containment of the fungal infection at the initial stages becomes crucial thus, preventing the development of a life-threatening situation. With the changing demands of clinical mycology, the field of fungal diagnostics has evolved and come a long way from traditional methods of microscopy and culturing to more advanced non-culture-based tools. With the advent of more powerful approaches such as novel PCR assays, T2 Candida, microfluidic chip technology, next generation sequencing, new generation biosensors, nanotechnology-based tools, artificial intelligence-based models, the face of fungal diagnostics is constantly changing for the better. All these advances have been reviewed here giving the latest update to our readers in the most orderly flow.

MAIN TEXT

A detailed literature survey was conducted by the team followed by data collection, pertinent data extraction, in-depth analysis, and composing the various sub-sections and the final review. The review is unique in its kind as it discusses the advances in molecular methods; advances in serology-based methods; advances in biosensor technology; and advances in machine learning-based models, all under one roof. To the best of our knowledge, there has been no review covering all of these fields (especially biosensor technology and machine learning using artificial intelligence) with relevance to invasive fungal infections.

CONCLUSION

The review will undoubtedly assist in updating the scientific community's understanding of the most recent advancements that are on the horizon and that may be implemented as adjuncts to the traditional diagnostic algorithms.

ARDS Clinical Practice Guideline 2021

BACKGROUND

The joint committee of the Japanese Society of Intensive Care Medicine/Japanese Respiratory Society/Japanese Society of Respiratory Care Medicine on ARDS Clinical Practice Guideline has created and released the ARDS Clinical Practice Guideline 2021.

METHODS

The 2016 edition of the Clinical Practice Guideline covered clinical questions (CQs) that targeted only adults, but the present guideline includes 15 CQs for children in addition to 46 CQs for adults. As with the previous edition, we used a systematic review method with the Grading of Recommendations Assessment Development and Evaluation (GRADE) system as well as a degree of recommendation determination method. We also conducted systematic reviews that used meta-analyses of diagnostic accuracy and network meta-analyses as a new method.

RESULTS

Recommendations for adult patients with ARDS are described: we suggest against using serum C-reactive protein and procalcitonin levels to identify bacterial pneumonia as the underlying disease (GRADE 2D); we recommend limiting tidal volume to 4-8 mL/kg for mechanical ventilation (GRADE 1D); we recommend against managements targeting an excessively low SpO2 (PaO2) (GRADE 2D); we suggest against using transpulmonary pressure as a routine basis in positive end-expiratory pressure settings (GRADE 2B); we suggest implementing extracorporeal membrane oxygenation for those with severe ARDS (GRADE 2B); we suggest against using high-dose steroids (GRADE 2C); and we recommend using low-dose steroids (GRADE 1B). The recommendations for pediatric patients with ARDS are as follows: we suggest against using non-invasive respiratory support (non-invasive positive pressure ventilation/high-flow nasal cannula oxygen therapy) (GRADE 2D), we suggest placing pediatric patients with moderate ARDS in the prone position (GRADE 2D), we suggest against routinely implementing NO inhalation therapy (GRADE 2C), and we suggest against implementing daily sedation interruption for pediatric patients with respiratory failure (GRADE 2D).

CONCLUSIONS

This article is a translated summary of the full version of the ARDS Clinical Practice Guideline 2021 published in Japanese (URL: https://www.jsicm.org/publication/guideline.html ). The original text, which was written for Japanese healthcare professionals, may include different perspectives from healthcare professionals of other countries.

ARDS clinical practice guideline 2021

BACKGROUND

The joint committee of the Japanese Society of Intensive Care Medicine/Japanese Respiratory Society/Japanese Society of Respiratory Care Medicine on ARDS Clinical Practice Guideline has created and released the ARDS Clinical Practice Guideline 2021.

METHODS

The 2016 edition of the Clinical Practice Guideline covered clinical questions (CQs) that targeted only adults, but the present guideline includes 15 CQs for children in addition to 46 CQs for adults. As with the previous edition, we used a systematic review method with the Grading of Recommendations Assessment Development and Evaluation (GRADE) system as well as a degree of recommendation determination method. We also conducted systematic reviews that used meta-analyses of diagnostic accuracy and network meta-analyses as a new method.

RESULTS

Recommendations for adult patients with ARDS are described: we suggest against using serum C-reactive protein and procalcitonin levels to identify bacterial pneumonia as the underlying disease (GRADE 2D); we recommend limiting tidal volume to 4-8 mL/kg for mechanical ventilation (GRADE 1D); we recommend against managements targeting an excessively low SpO₂ (PaO₂) (GRADE 2D); we suggest against using transpulmonary pressure as a routine basis in positive end-expiratory pressure settings (GRADE 2B); we suggest implementing extracorporeal membrane oxygenation for those with severe ARDS (GRADE 2B); we suggest against using high-dose steroids (GRADE 2C); and we recommend using low-dose steroids (GRADE 1B). The recommendations for pediatric patients with ARDS are as follows: we suggest against using non-invasive respiratory support (non-invasive positive pressure ventilation/high-flow nasal cannula oxygen therapy) (GRADE 2D); we suggest placing pediatric patients with moderate ARDS in the prone position (GRADE 2D); we suggest against routinely implementing NO inhalation therapy (GRADE 2C); and we suggest against implementing daily sedation interruption for pediatric patients with respiratory failure (GRADE 2D).

CONCLUSIONS

This article is a translated summary of the full version of the ARDS Clinical Practice Guideline 2021 published in Japanese (URL: https://www.jrs.or.jp/publication/jrs_guidelines/). The original text, which was written for Japanese healthcare professionals, may include different perspectives from healthcare professionals of other countries.

Fungal infections diagnosis - Past, present and future

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

Invasive Pulmonary Aspergillosis in Chronic Obstructive Pulmonary Disease Exacerbations

Nowadays, reports in the literature support that patients with severe chronic obstructive pulmonary disease (COPD) are at higher risk to develop invasive pulmonary aspergillosis (IPA). However, the interpretation of Aspergillus-positive cultures from the airways in critically ill COPD is still a challenge. Indeed, as the patient could be merely colonized, tissue samples are required to ascertain IPA diagnosis but they are rarely obtained before death. Consequently, diagnosis is often only suspected on the basis of a combination of three elements: clinical characteristics, radiological images (mostly thoracic CT scan), and microbiological, and occasionally serological, results. To facilitate the analysis of these data, several algorithms have been developed, and the best effectiveness has been demonstrated by the Clinical algorithm. This is of importance as IPA prognosis in these patients remains presently very poor and using such an algorithm could promote prompter diagnosis, early initiation of treatment, and subsequently improved outcome.While the most classical presentation of IPA in critically ill COPD patients features a combination of obstructive respiratory failure, antibiotic-resistant pneumonia, recent or chronic corticosteroid therapy, and positive Aspergillus cultures from the lower respiratory tract, the present article will also address less typical presentations and discuss the most appropriate treatments which could alter prognosis.

Galactomannan detection for invasive aspergillosis in immunocompromised patients

BACKGROUND

Invasive aspergillosis is the most common life-threatening opportunistic invasive mycosis in immunocompromised patients. A test for invasive aspergillosis should neither be too invasive nor too great a burden for the already weakened patient. The serum galactomannan enzyme-linked immunosorbent assay (ELISA) seems to have the potential to meet both requirements.

OBJECTIVES

To obtain summary estimates of the diagnostic accuracy of galactomannan detection in serum for the diagnosis of invasive aspergillosis.

SEARCH METHODS

We searched MEDLINE, EMBASE and Web of Science with both MeSH terms and text words for both aspergillosis and the sandwich ELISA. We checked the reference lists of included studies and review articles for additional studies. We conducted the searches in February 2014.

SELECTION CRITERIA

We included cross-sectional studies, case-control designs and consecutive series of patients assessing the diagnostic accuracy of galactomannan detection for the diagnosis of invasive aspergillosis in patients with neutropenia or patients whose neutrophils are functionally compromised. The reference standard was composed of the criteria given by the European Organization for Research and Treatment of Cancer (EORTC) and the Mycoses Study Group (MSG).

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed quality and extracted data. We carried out meta-analysis using the bivariate method. We investigated sources of heterogeneity by adding potential sources of heterogeneity to the model as covariates.

MAIN RESULTS

We included 54 studies in the review (50 in the meta-analyses), containing 5660 patients, of whom 586 had proven or probable invasive aspergillosis. When using an optical density index (ODI) of 0.5 as a cut-off value, the sensitivity of the test was 82% (73% to 90%) and the specificity was 81% (72% to 90%). At a cut-off value of 1.0 ODI, the sensitivity was 72% (65% to 80%) and the specificity was 88% (84% to 92%). At a cut-off value of 1.5 ODI, the sensitivity was 61% (47% to 75%) and the specificity was 93% (89% to 97%). None of the potential sources of heterogeneity had a statistically significant effect on either sensitivity or specificity.

AUTHORS' CONCLUSIONS

If we used the test at a cut-off value of 0.5 ODI in a population of 100 patients with a disease prevalence of 9% (overall median prevalence), two patients who have invasive aspergillosis would be missed (sensitivity 82%, 18% false negatives), and 17 patients would be treated unnecessarily or referred unnecessarily for further testing (specificity 81%, 19% false negatives). If we used the test at a cut-off value of 1.5 in the same population, that would mean that four invasive aspergillosis patients would be missed (sensitivity 61%, 39% false negatives), and six patients would be treated or referred for further testing unnecessarily (specificity 93%, 7% false negatives). These numbers should, however, be interpreted with caution because the results were very heterogeneous.

Aspergillus Polymerase Chain Reaction: Systematic Review of Evidence for Clinical Use in Comparison With Antigen Testing

BACKGROUND

Aspergillus polymerase chain reaction (PCR) was excluded from the European Organisation for the Research and Treatment of Cancer/Mycoses Study Group (EORTC/MSG) definitions of invasive fungal disease because of limited standardization and validation. The definitions are being revised.

METHODS

A systematic literature review was performed to identify analytical and clinical information available on inclusion of galactomannan enzyme immunoassay (GM-EIA) (2002) and β-d-glucan (2008), providing a minimal threshold when considering PCR. Categorical parameters and statistical performance were compared.

RESULTS

When incorporated, GM-EIA and β-d-glucan sensitivities and specificities for diagnosing invasive aspergillosis were 81.6% and 91.6%, and 76.9% and 89.4%, respectively. Aspergillus PCR has similar sensitivity and specificity (76.8%-88.0% and 75.0%-94.5%, respectively) and comparable utility. Methodological recommendations and commercial PCR assays assist standardization. Although all tests have limitations, currently, PCR is the only test with independent quality control.

CONCLUSIONS

We propose that there is sufficient evidence that is at least equivalent to that used to include GM-EIA and β-d-glucan testing, and that PCR is now mature enough for inclusion in the EORTC/MSG definitions.

Galactomannan antigen detection in the diagnosis of invasive aspergillosis

Invasive aspergillosis is a serious and lethal infection among immunocompromised patients, with reported mortality rates as high as 74-92%. The high mortality is related to the severe immunosuppression experienced by these patients as well as the difficulties for physicians in arriving at a timely diagnosis. Definitive diagnostic procedures (tissue biopsy for histopathology and culture) are often precluded by severe cytopenias and coagulation abnormalities. The development of minimally invasive, nonculture diagnostic methods is a major advance in the early diagnosis of invasive aspergillosis. Galactomannan is a heteropolysaccharide (mannan core and side residues of galactofuranosyl units) present in the cell wall of Aspergillus spp. The double sandwich enzyme immunoassay, which detects galactomannan in serum samples, has been available in Europe for almost a decade and in the USA since May 2003, for the diagnosis of invasive aspergillosis. However, availability of the double galactomannan enzyme immunoassay is center variable in the USA and, although its analytical performance in the diagnosis of invasive aspergillosis is well documented, its routine use in clinical practice is limited. As an adjunct in the diagnosis and management of invasive aspergillosis, incorporation of the galactomannan enzyme immunoassay into clinical trials will help to further define its role.

Invasive aspergillosis in hematopoietic stem cell and solid organ transplantation

Invasive aspergillosis (IA) is currently an important cause of morbidity and mortality in hematopoietic stem cell transplant and solid organ transplant recipients. A high index of suspicion and careful clinical and radiological examinations are the keys to identifying infected patients early. Chest computerized axial tomography is extremely useful in diagnosing pulmonary aspergillosis. Microbiologic or histologic identification of infection, however, remain essential. Successful management of invasive fungal infections depends on timely and appropriate treatment. There are multiple variables associated with survival in transplant patients with IA. Understanding these prognostic factors may assist in the development of treatment algorithms and clinical trials. In contrast to adult patients, large prospective comparative studies have not been performed in pediatric patients with IA. Moreover, pediatric subgroups have not been analyzed in published studies that include a broader age range. Clinicians treating pediatric IA are largely left with the results of uncontrolled trials, observatory surveys, salvage therapy data and extrapolations from adult studies to guide their treatment choices. The aim of this article is to state the main characteristics of IA in both pediatric and adult populations.

Invasive mould infections: a multi-disciplinary update

Systemic fungal infections remain a significant cause of mortality in neutropenic and immunocompromised patients, despite advances in their diagnosis and treatment. The incidence of such infections is rising due to the use of intensive chemotherapy regimens in patients with solid tumours or haematological cancers, the increasing numbers of allogeneic haematopoietic stem cell and solid organ transplants, and the use of potent immunosuppressive therapy in patients with autoimmune disorders. In addition, the epidemiology of systemic fungal infections is changing, with atypical species such as Aspergillus terreus and zygomycetes becoming more common. Treatment has traditionally focused on empirical therapy, but targeted pre-emptive therapy in high-risk patients and prophylactic antifungal treatment are increasingly being adopted. New treatments, including lipid formulations of amphotericin B, second-generation broad-spectrum azoles, and echinocandins, offer effective antifungal activity with improved tolerability compared with older agents; the potential impact of these treatments is reflected in their inclusion in current treatment and prophylaxis guidelines. New treatment strategies, such as aerosolized lipid formulations of amphotericin B, may also reduce the burden of mortality associated with systemic fungal infections. The challenge is to identify ways of coupling potentially effective treatments with early and reliable identification of patients at highest risk of infection.

Classification of invasive fungal disease in patients with acute myeloid leukaemia

Invasive fungal diseases (IFD) are a major cause of morbidity and mortality in patients with acute myeloid leukaemia (AML). Their incidence has risen dramatically in recent years. The diagnosis of IFDs remains difficult, even if the European Organisation for the Research and Treatment of Cancer (EORTC)/Mycosis Study Group (MSG) criteria are applied for study purposes to classify the likelihood of these infections. These criteria have been developed for clinical trials, and their relevance in clinical settings outside a clinical trial remains unknown. We evaluated the impact of the EORTC/MSG criteria and a modification thereof for clinical purposes in patients with AML. We retro-spectively analysed 100 AML patients for the occurrence of IFD. First, EORTC/MSG criteria were applied to classify the patients. Second, a modified version of these criteria already used in clinical trials was used to re-classify the patients. Fifty-seven patients developed an invasive fungal infection. Following the original criteria, 43% were classified as 'possible' IFD, whereas 7% each were classified as 'probable' and 'proven' IFD. After application of the modified criteria, only 9% of the patients remained 'possible' IFD, whereas 41% were 'probable'. The occurrence of 'proven' cases was not altered by the modification and thus remained 7%. The application of modified criteria for the classification of IFD in AML patients leads to a considerable shift from 'possible' IFD (according to conventional EORTC criteria) towards 'probable' IFD. Nevertheless, neither the old EORTC criteria nor their modification was designed for use in clinical practice. As this study underscores the uncertainty in the diagnosis of IFD, the need for a clinically applicable classification is obvious.

The role of bronchoalveolar lavage galactomannan in the diagnosis of pediatric invasive aspergillosis

BACKGROUND

: Molecular biomarkers such as the galactomannan assay are of increasing interest in clinical settings for diagnosis of invasive aspergillosis (IA). The use of bronchoalveolar lavage galactomannan (BAL GM) is being validated in adult populations, but has not been systematically evaluated in pediatric patients.

METHODS

: A retrospective analysis was performed of patients for whom GM assays from BAL were submitted between November 1, 2006 and November14, 2007 at Childrens Hospital Los Angeles. Medical charts were reviewed and patients were categorized as having no, possible, probable, and proven IA, per established definitions.

RESULTS

: Of 85 pediatric patients who had a BAL GM submitted during the study, 59 were immunocompromised. Three patients were identified as having proven IA, 6 had probable IA, 37 had possible IA, and 39 had no evidence of IA; 38 had a concurrent serum GM performed. A positive, linear correlation was established between BAL and serum GM, using OD index values (rho = 0.48, P = 0.002). Among immunocompromised patients, receiver operating characteristic curves demonstrated an optimal BAL GM OD cut-off value of 0.87, that yielded a sensitivity for probable/proven IA of 78% and a specificity of 100%. At 0.87, the positive and negative predictive values among immunocompromised patients were 58% and 96%, respectively.

CONCLUSIONS

: We found a correlation between BAL GM values and a diagnosis of IA. We also noted a linear relationship between serum and BAL GM values. Receiver operating characteristic curves obtained from our pediatric data validate the current cut off for serum and suggest a possible cut off for BAL specimens.

Utility of galactomannan enzyme immunoassay and (1,3) beta-D-glucan in diagnosis of invasive fungal infections: low sensitivity for Aspergillus fumigatus infection in hematologic malignancy patients

Previous studies have reported that galactomannan (GM) enzyme immunoassay and 1,3 beta-glucan (BG) assay may be useful diagnostic tools, but their sensitivities are variable. We compared the performances of both tests. Between October 2002 and May 2005, 82 patients were prospectively monitored for 12 weeks. A total of 414 samples were tested by GM assay and 409 samples were tested by BG assay for the following four groups of patients: those with invasive aspergillosis (IA), those with other mold infections (Fusarium, scedosporium, zygomycosis, etc.), those with candidemia, and control patients. Blood samples were obtained twice on week 1 and once every other week for a total of 12 weeks. Patients in the invasive fungal infection groups had comparable risk factors. The sensitivity of the GM test was significantly higher for patients with IA due to non-fumigatus Aspergillus species than for patients with IA due to Aspergillus fumigatus (49% versus 13%; P < 0.0001) or with other mold infections (49% versus 6%; P < 0.0001). However, the sensitivity range (47% to 64%) and specificity (88%) of the BG assay were comparable among all patients tested, regardless of the infecting pathogen. The performance of GM-based diagnosis appears to be better for detecting non-fumigatus Aspergillus species. The diagnostic marker BG was shown to have a higher sensitivity than that of GM in detecting IA and other mold infections in hematologic malignancy patients.

Galactomannan detection for invasive aspergillosis in immunocompromized patients

BACKGROUND

Invasive aspergillosis (IA) is the most common life-threatening opportunistic invasive mycosis in immunocompromized patients. A test for IA needs to be not too invasive and not too big a burden for the already weakened patient. The serum galactomannan ELISA seems to have potential for both requirements.

OBJECTIVES

To obtain summary estimates of the diagnostic accuracy of galactomannan detection in serum for the diagnosis of IA.

SEARCH STRATEGY

We searched MEDLINE, EMBASE and Web of Science with both Medical Headings and text words for both aspergillosis and the sandwich ELISA. We checked reference lists of included studies and review articles for additional studies.

SELECTION CRITERIA

Cross-sectional studies, case-control designs and consecutive series of patients assessing the diagnostic accuracy of galactomannan detection for the diagnosis of IA in patients with neutropenia or patients whose neutrophils are functionally compromised were included. The reference standard was composed of the criteria given by the European Organization for Research and Treatment of Cancer (EORTC) and the Mycoses Study Group (MSG).

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed quality and extracted data

MAIN RESULTS

Thirty studies were included in the meta-analyses, with a median prevalence of IA (proven or probable) of 7.7%. Seven of these (901 patients) reported results for an Optical Density Index (ODI) of 0.5 as cut-off value. The overall sensitivity in these studies was 78% (61% to 89%) and overall specificity was 81% (72% to 88%). Twelve studies (1744 patients) reported the results for cut-off value of 1.0 ODI, overall sensitivity was 75% (59% to 86%) and mean specificity 91% (84% to 95%). Seventeen studies (2600 patients) reported the results for cut-off value 1.5 ODI, sensitivity was 64% (50% to 77%) and mean specificity 95% (91% to 97%).

AUTHORS' CONCLUSIONS

At a cut-off value 0.5 ODI in a population of 100 patients with a disease prevalence of 8% (overall median prevalence), 2 patients who have IA, will be missed (sensitivity 78%, 22% false negatives), and 17 patients will be treated or further referred unnecessarily (specificity of 81%, 19% false negatives). If we use the test at cut-off value 1.5 in the same population, that will mean that 3 IA patients will be missed (sensitivity 64%, 36% false negatives) and 5 patients will be treated or referred unnecessarily (specificity of 95%, 5% false negatives). These numbers should however be interpreted with caution, because the results were very heterogeneous.

False-positive results by the platelia Aspergillus galactomannan antigen test for patients treated with amoxicillin-clavulanate

The Aspergillus galactomannan test is a valuable tool in the diagnosis of invasive aspergillosis. We hereby report a high rate of false-positive results by the Platelia Aspergillus galactomannan antigen test (Bio-Rad Laboratories) for patients treated with amoxicillin-clavulanate.

Prospective Aspergillus galactomannan antigen testing in pediatric hematopoietic stem cell transplant recipients

BACKGROUND

The galactomannan (GM) assay is an approved noninvasive test for detection of invasive aspergillosis (IA) that has been validated in adult patients with hematologic malignancies who are undergoing bone marrow transplantation. There have been few studies with this assay in pediatric patients, but early reports suggest that there may be differences in the performance such that false-positive GM tests in pediatric patients are more common than in adult patients.

METHODS

We performed a prospective study in pediatric hematopoietic stem cell transplant recipients with twice-weekly sampling for GM detection during the highest risk periods of neutropenia and graft-versus-host disease. We analyzed 826 serum samples from 64 patients, including 15 serum samples from one patient diagnosed with probable IA according to defined criteria.

RESULTS

Twenty of 811 samples tested positive on repeat testing (specificity, 97.5%; 95% CI: 96.2-98.4%) including samples from 8 of 63 patients without clinical evidence of IA according to study criteria (specificity, 87.3%; 95% CI: 76.9-93.4%). Eleven patients received piperacillin/tazobactam therapy, and 4 of the 11 patients had a positive assay result coinciding with the dates of piperacillin/tazobactam administration. When samples from these patients were excluded, specificity increased to 98.4% (95% CI: 97.2-99.1%) by sample and to 91.5% (95% CI: 81.6-96.3%) by patient.

CONCLUSIONS

The GM assay holds promise for early, noninvasive diagnosis of IA in high-risk children and false-positive results were not common or unexplainable. This study supports further validation of this assay in a large-scale, pediatric-dedicated format.

Advances in the serological diagnosis of invasive Aspergillus infections in patients with haematological disorders

A reliable diagnosis of invasive aspergillosis in patients with haematological malignancies is seldom achieved antemortem. Conventional laboratory diagnostic methods are insensitive and time-consuming, resulting in late diagnosis and treatment and contributing to unacceptably high mortality. As a result, routine antifungal prophylaxis and early empirical treatment have been recommended. However, overtreatment associated with these strategies results in increased toxicity and cost. The use of sensitive and rapid non-culture-based diagnostic assays, such as detection of Aspergillus antigens (galactomannan, beta-D-glucan) or detection of genomic DNA sequences may allow a shift in emphasis from empirical to pre-emptive therapy, especially when substantiated by suggestive radiological findings. These new tools may be used to confirm a presumed diagnosis of invasive aspergillosis, or, when used to screen high-risk patients, may identify an infection at the early stage of disease. The excellent negative predictive value of these assays should convince clinicians to withhold antifungal therapy in persistently febrile neutropenic patients with no other signs of fungal infection. On the other hand, consecutive positive results in a high-risk population should at least trigger a complete diagnostic work-up. This review will focus on the diagnostic utility as well as on the pitfalls of serial screening for the presence of circulating fungal antigens in haematology patients.

Optimization of the cutoff value for the Aspergillus double-sandwich enzyme immunoassay

BACKGROUND

Many health care centers worldwide use the Platelia Aspergillus enzyme immunoassay (PA-EIA; Bio-Rad Laboratories) for diagnosis of invasive aspergillosis (IA). A cutoff optical density (OD) index of 1.5 was originally recommended by the manufacturer, but in practice, most institutions use lower cutoff values. Moreover, a cutoff OD index of 0.5 was recently approved in the United States. In the present study, we set out to optimize the cutoff level by performing a retrospective analysis of PA-EIA values for samples that had been obtained prospectively from adult patients at risk for IA at 2 European health care centers.

METHODS

In total, 239 treatment episodes were included of which there were 19 episodes of proven IA and 19 episodes of probable IA. Per-episode and per-test analyses and receiver operating characteristic curves were used to determine the optimal cutoff value.

RESULTS

In the per-episode analysis, lowering the cutoff OD index for positivity from 1.5 to 0.5 increased the overall sensitivity by 21% (from 76.3% to 97.4%) but decreased the overall specificity by 7% (from 97.5% to 90.5%). Requiring 2 consecutive samples with an OD index > or = 0.5 resulted in the highest test accuracy, with an improved positive predictive value. At a cutoff OD index of 0.5, the antigen test result was positive during the week before conventional diagnosis in 65% of cases and during the week of diagnosis in 79.5% of cases.

CONCLUSIONS

A cutoff OD index of 0.5--identical to the approved cutoff in the United States--improves the overall performance of the PA-EIA for adult hematology patients.

Diagnosis of Invasive Aspergillosis Using a Galactomannan Assay: A Meta-Analysis

BACKGROUND

A double-sandwich enzyme-linked immunosorbent galactomannan assay has been approved for surveillance for invasive aspergillosis in immunocompromised patients. We undertook a meta-analysis to assess the accuracy of a galactomannan assay for diagnosing invasive aspergillosis.

METHODS

Studies of the galactomannan assay that used the European Organization for Research and Treatment of Cancer or similar criteria as a reference standard and provided data to calculate sensitivity and specificity were included. Pooled sensitivity and specificity and summary measures of accuracy, Q* (the upper left-most point on the summary receiver-operating characteristic curve), mean D (a log odds ratio), and Youden index were calculated. Subgroup analyses were performed to explore heterogeneity.

RESULTS

Twenty-seven studies from 1966 to 28 February 2005 were included. Overall, the galactomannan assay had a sensitivity of 0.71 (95% confidence interval [CI], 0.68-0.74) and specificity of 0.89 (95% CI, 0.88-0.90) for proven cases of invasive aspergillosis. The Youden index, mean D, and Q* were 0.54 (95% CI, 0.41-0.65), 2.74 (95% CI, 21.12-3.36), and 0.80 (95% CI, 0.74-0.86), respectively, indicating moderate accuracy. Subgroup analyses showed that the performance of the test differed by patient population and type of reference standard used. Significant heterogeneity was present.

CONCLUSIONS

The galactomannan assay has moderate accuracy for diagnosis of invasive aspergillosis in immunocompromised patients. The test is more useful in patients who have hematological malignancy or who have undergone hematopoietic cell transplantation than in solid-organ transplant recipients. Further studies with attention to the impact of antifungal therapy, rigorous assessment of false-positive test results, and assessment of the utility of the test under nonsurveillance conditions are needed.

Evaluation of pan-fungal PCR assay andAspergillusantigen detection in the diagnosis of invasive fungal infections in high risk paediatric cancer patients

Profound and prolonged neutropenia following chemotherapy is a major risk factor for systemic fungal infection. As the early diagnosis of invasive fungal infection (IFI) is difficult, these infections are still associated with high morbidity and mortality. Recently, Pan-fungal polymerase chain reaction (PCR) has been a promising aid in rapid, early diagnosis of IFI. During the past few years, increasing numbers of suspected IFIs were encountered at our institution in patients with prolonged neutropenia after intensified immunosuppressive chemotherapy. The aim of this study was to investigate the diagnostic utility of both the aspergillus galactomannan (GM) antigen and the pan-fungal PCR assay in the diagnosis of IFI in high risk febrile neutropenic paediatric cancer patients. During one year period, 91 febrile neutropenic (FN) paediatric cases at high risk for developing IFI while receiving chemotherapy were investigated at National Cancer Institute, Egypt. These patients were subjected to clinical evaluation, chest CT scan, conventional blood cultures for bacterial and fungal pathogens, aspergillus GM antigen detection and PCR assay utilizing pan-fungal primers. Of the 91 FN episodes, 15 were proven IFI; whereas 27 cases were either probable (n=13) or possible IFI (n=14), and 49 were unlikely to be IFI episodes. Based on positive results for proven/probable IFI and compared to culture results, Pan-fungal PCR showed sensitivity, specificity, positive and negative predictive values of 75%, 92%, 84% and 87%; respectively. Aspergillus antigen test showed a sensitivity of 79%, specificity of 61%, positive and negative predictive values of 54% and 83%; respectively. A negative PCR in the proven and probable cases was closely related to previous antifungal therapy for a prior history of IFI. In patients at high risk for IFI, neither the sensitivity, nor specificity of the GM test was sufficient. The results of PCR assay was reasonably specific but not very sensitive and had a chance of missing the diagnosis of IFI. The PCR assay seems a promising test for objectively defining IFI, but is not recommended as the only tool for diagnosing IFI. Combining microscopy, culture, and PCR may improve the diagnostic outcome.

Surveillance of nosocomial infections in paediatric recipients of bone marrow or peripheral blood stem cell transplantation during neutropenia, compared with adult recipients

The aim of this prospective study was to analyse the incidence of nosocomial infections (NIs) during neutropenia after haematopoietic stem cell transplantation (HSCT) in paediatric and adult patients. Diagnosis of NI followed the modified surveillance protocol of the German National Reference Centre for Surveillance of NIs. During the 24-month study period, 38 and 39 transplantations were performed in paediatric and adult patients, respectively. Eighty percent and 92% of the paediatric and adult patients, respectively, underwent allogenic HSCT. In total, 1156 neutropenic days were documented. The incidence of NI during neutropenia in all recorded cases was 38.9 NI per 1000 days, without significant difference between the groups. No difference was found in the incidence rates of pneumonia, while there was a trend towards a higher incidence of bloodstream infection in adult patients. Significantly more episodes of fever of unknown origin were found in paediatric than adult patients. Pathogens were isolated in 19 of 45 cases of NI. Of the clinically documented infections, Gram-positive organisms were isolated in 79%, Gram-negative organisms were isolated in 16% and fungi were isolated in 5%. Surveillance of NI is an effective instrument to control the quality of health care. It should focus on device-associated infections or specific high-risk targets such as nosocomial pneumonia.

Recent Advances of Serodiagnosis for Systemic Fungal Infections

Serological surrogate tests for invasive fungal infection have been used practically in Japan. The Aspergillus galactomannan antigen detection kit by enzyme linked immunosorbent assay is the most reliable test for making a diagnosis of invasive aspergillosis. But in recent years, occurrences of false positive and negative results have also been reported by several investigators. Therefore, evaluation of the results of this assay should be done carefully in the clinical stage. Moreover, some other methods to detect the Aspergillus antigen or anti Aspergillus antibody in serum have also been reported. The problem of false positive results due to the frequent occurrence of non-specific reaction in the alkaline treatment, chromogenic automated kinetic assay to measure (1-->3)-beta-D-glucan had been noticed in Japan. But this important problem was resolved by improvement of the pretreatment reagent in this kit in July 2005. In this manuscript, I describe recent trends of serological surrogate tests for Aspergillus infection and the process of improvement of the (1-->3)-beta-D-glucan measurement kit.

Design Issues in Studies Evaluating Diagnostic Tests for Aspergillosis

Although invasive aspergillosis is recognized as an increased concern for immunosuppressed patients, establishing an early diagnosis remains a challenge. Current methods for diagnosis, including sensitive radiography and invasive procedures to identify organisms in affected tissues, provide an early diagnosis for only a small proportion of patients infected with Aspergillus species. The availability of a standardized assay to detect circulating Aspergillus galactomannan, the BioRad Platelia Aspergillus galactomannan enzyme immunoassay, should be considered as a valuable tool. However, at present, clinical utility is hampered by controversies surrounding the performance of the test and an apparent lack of definitive data. These controversies emphasize the complexity inherent in analyzing diagnostic tests for aspergillosis. The widespread availability of a standardized assay may now allow us to address the multiple sources of variability and bias via large, cooperative studies.

Pediatric aspergillosis: disease and treatment differences in children

Invasive aspergillosis is an increasing problem, yet there are few specific data on pediatric aspergillosis. The underlying patient diseases and treatments differ in children and adults, and there is a heterogeneity of invasive aspergillosis that extends to children. Although new diagnostic tools hold great promise for adult patients, it appears that they have limited usefulness in children without the appropriate testing. Antifungal management of pediatric aspergillosis also requires unique dosing schemes that are not used in adult patients.

Invasive aspergillosis in organ transplant recipients: new issues in epidemiologic characteristics, diagnosis, and management

Changing transplantation practices, novel immunosuppressive protocols, and evolving recipient characteristics have led to notable changes in the epidemiology of invasive aspergillosis in transplant recipients. The frequency of disseminated infection and of central nervous system involvement has declined significantly in organ transplant recipients in the recent years. Amongst variables that may have contributed to these trends is an overall lesser severity of illness of transplant recipients in the current era. Calcineurin-inhibitor immunosuppressive agents may also have had a role in altering the disease course and the risk of dissemination. A new paradigm in the management of post-transplant immunosuppression is the use of calcineurin-inhibitor and corticosteroid sparing regimens by pretreatment of the recipient with T-cell depleting agents (Campath 1-H or thymoglobulin) and utilization of minimal post-transplant immunosuppression. The impact of these potent lymphoablative regimens on opportunistic mycoses in organ transplant recipients remains to be fully discerned. Although still unacceptably high, the mortality rate in organ transplant recipients with invasive aspergillosis in the current era appears to have declined. A focus of a great interest and controversy is the use of combination therapy for invasive aspergillosis in transplant recipients.

Aspergillus infections in transplant recipients

Aspergillus infections are occurring with an increasing frequency in transplant recipients. Notable changes in the epidemiologic characteristics of this infection have occurred; these include a change in risk factors and later onset of infection. Management of invasive aspergillosis continues to be challenging, and the mortality rate, despite the use of newer antifungal agents, remains unacceptably high. Performing molecular studies to discern new targets for antifungal activity, identifying signaling pathways that may be amenable to immunologic interventions, assessing combination regimens of antifungal agents or combining antifungal agents with modulation of the host defense mechanisms, and devising diagnostic assays that can rapidly and reliably diagnose infections represent areas for future investigations that may lead to further improvement in outcomes.

Diagnosis of IPA in HIV: the role of the chest X-ray and radiologist

The role of clinical information and chest film for the discrimination between invasive pulmonary aspergillosis (IPA) and its differential diagnoses in human immunodeficiency virus (HIV) infection was studied. The diagnostic performance of clinical information and chest film alone and in combination was studied for eight internists and eight radiologists with regular exposure to IPA patients. The multicenter case sample consisted of 25 patients with proven IPA and 25 with other pulmonary diseases typical for HIV. The cases were presented on a CD-ROM. Receiver operating characteristics (ROC) methodology was employed. With clinical information alone, internists achieved the highest diagnostic performance (area under curve/AUC=0.84). Viewing the chest films did not contribute to their performance (AUC=0.80, P=0.26). The radiologist's performance on the basis of viewing the chest film (AUC=0.75) increased significantly ( P=0.012) when clinical information (AUC=0.83) was supplied. IPA cases with characteristic radiological appearance were correctly identified in 90% with chest film. For radiologists with regular exposure to HIV patients, chest films hold relevant information and contribute to the determination in cases with characteristic radiological appearance. Overall and especially in cases with less characteristic radiological appearance, they have significant profit from full access to the clinical data. For internists with regular exposure to HIV patients, chest films do not provide information essential for the verification or differentiation of potential IPA.

Choices aplenty: antifungal prophylaxis in hematopoietic stem cell transplant recipients

The incidence of invasive fungal infection (IFIs) in hematopoietic stem cell transplantation (HSCT) recipients ranges from 10 to 25% with an overall case fatality rate of up to 70-90%. Candida and Aspergillus genera remain the two most common pathogens. Although fluconazole prophylaxis in this population has been moderately effective in reducing mortality due to invasive candidiasis, this agent does not have activity against invasive aspergillosis (IA) and other mould. Several new agents such as voriconazole and caspofungin have enhanced potency and broad-spectrum antifungal activity and show promising results against yeasts and filamentous fungi when given as therapy and as chemoprophylaxis. Further, new diagnostic tools to detect circulating fungal antigens in biological fluids and PCR-based methods to detect species or genus-specific DNA or RNA have been developed. Incorporating these techniques along with clinical criteria appear to improve the accuracy of preclinical diagnosis of IFIs. Such approaches may alter the current treatment strategy from prophylaxis to pre-emptive therapy, thereby potentially decreasing cost and toxicity in high-risk patients.

Detection of Aspergillus galactomannan by enzyme immunoabsorbent assay in recipients of allogeneic hematopoietic stem cell transplantation: a prospective study

BACKGROUND

Invasive aspergillosis (IA) has become the leading infectious cause of death after allogeneic hematopoietic stem cell transplantation (allo-HSCT). This is partially because of the lack of a sensitive, specific, and noninvasive diagnostic test. New diagnostic tests for IA, such as the detection of Aspergillus galactomannan antigen (AGA) by sandwich enzyme-linked immunoabsorbent assay (ELISA), have recently been described. This study validates the usefulness of this diagnostic tool in the allo-HSCT setting.

METHODS

From January 1999 to January 2001, all consecutive adult patients undergoing allo-HSCT were prospectively studied with a galactomannan antigenemia assay (ELISA test) twice weekly from admission until death or discharge, and weekly afterward if the patient received immunosuppressive therapy. Proven, probable, and possible IA were defined according to the European Organization for Research and Treatment of Cancer/Mycoses Study Group criteria.

RESULTS

During the 2 years of study, 74 patients underwent an allo-HSCT. A total of 832 serum samples were collected. According to the European Organization for Research and Treatment of Cancer/Mycoses Study Group criteria, it was ascertained that 66 patients did not fulfill any criteria of IA, 2 patients were classified with possible IA, 5 patients were classified with probable IA, and 1 patient was classified with proven IA. Fourteen samples were positive for AGA, all from patients with IA. The sensitivity and specificity of the test were 75% and 100%, respectively. The positive predictive and negative predictive values were 100% and 97%, respectively.

CONCLUSIONS

In this study, AGA detection was clearly related to IA. Although the ELISA test did not have any role in the anticipation of the diagnosis, it clarifies the diagnosis of IA in allo-HSCT.

Isolation of Neosartorya pseudofischeri from blood: first hint of pulmonary Aspergillosis

We report a case of invasive pulmonary aspergillosis caused by Neosartorya pseudofischeri S. W. Peterson [anamorph Aspergillus thermomutatus (Paden) S. W. Peterson]. The diagnosis was initially based on a positive blood culture for a strain isolated from a neutropenic patient by means of a BACTEC 9050 blood culture system. The final diagnosis was established based on X-ray and computer tomography scan results as well as the detection of Aspergillus antigen in the patient's serum.

Treatment with Piperacillin‐Tazobactam and False‐PositiveAspergillusGalactomannan Antigen Test Results for Patients with Hematological Malignancies

We report the occurrence of a high rate of false-positive test results during the surveillance of hematology patients for galactomannan (GM) antigenemia. Among 218 patients surveyed from June 2002 through June 2003, 42 (19.3%) had > or =1 serum sample positive for GM (optical density index, >1.5). Of these patients, 38 had no additional evidence of invasive aspergillosis, and, therefore, their test results were considered to be false-positives. Case-control analysis showed that treatment with piperacillin-tazobactam was the only risk factor significantly associated with receiving false-positive test results. When tested for GM antigen, 3 of 4 piperacillin-tazobactam batches had positive results. Physicians should be aware of the possible interference of treatment with piperacillin-tazobactam when interpreting the results of the GM assay.

Infections in patients with cancer undergoing chemotherapy: aetiology, prevention, and treatment

Patients with cancer who are undergoing chemotherapy are highly susceptible, especially if neutropenic, to almost any type of bacterial or fungal infection. These infections cause substantial morbidity and mortality. Prophylactic use of antibiotics should be avoided, however, since this practice is associated with a risk of emergence of resistant bacteria and it does not lower the risk of death. However, chemoprophylaxis has a role for candidal fungal infections. Because infection in a neutropenic host can be rapidly fatal if not treated, the empirical administration of broad-spectrum intravenous antibiotics is generally indicated for these patients, and the local frequencies, susceptibility, and resistance patterns of various pathogens must be taken into account. Once therapy has been initiated, changes in antibiotic regimens during the first 5 days are useless unless the patient's clinical condition deteriorates substantially. The treatment of invasive fungal infections is particularly difficult. Many unsolved questions remain, and studies are proposed here that may shed light on these issues.

Clinical applicability of the new EORTC/MSG classification for invasive pulmonary aspergillosis in patients with hematological malignancies and autopsy-confirmed invasive aspergillosis

Diagnosis of invasive pulmonary aspergillosis (IPA) is often difficult. Recently, the European Organization for Research and Treatment of Cancer/Mycoses Study Group (EORTC/MSG) has proposed new criteria for the classification of invasive fungal infections. We have studied the clinical applicability of this classification in 22 patients with hematological malignancies who had IPA at autopsy. While alive, according to the EORTC/MSG criteria, only 2 patients were classified as having proven IPA, 6 as probable, 13 as possible, and 1 was unclassifiable. Of the patients, 64% had no microbiological or major clinical criteria before death. Although the EORTC/MSG criteria are an important step forward in the standardization of definitions used for IPA in clinical research studies, most patients who die with extensive lung disease only reach a level of possible or probable IPA during life, further highlighting that these guidelines should not be used for clinical decision-making.

Screening for circulating galactomannan as a noninvasive diagnostic tool for invasive aspergillosis in prolonged neutropenic patients and stem cell transplantation recipients: a prospective validation

The diagnosis of invasive aspergillosis (IA) in patients with hematologic disorders is not straightforward; lack of sensitive and specific noninvasive diagnostic tests remains a major obstacle for establishing a precise diagnosis. In a series of 362 consecutive high-risk treatment episodes that were stratified according to the probability of IA based on recently accepted case definition sets, the potential for diagnosis of serial screening for circulating galactomannan (GM), a major aspergillar cell wall constituent was validated. After incorporating postmortem findings to allow a more accurate final analysis, this approach proved to have a sensitivity of 89.7% and a specificity of 98.1%. The positive and negative predictive values equaled 87.5% and 98.4%, respectively. False-positive reactions occurred at a rate of 14%, although this figure might be overestimated due to diagnostic uncertainty. More or less stringent criteria of estimation could highly influence sensitivity, which ranged from 100% to 42%; the impact on other test statistics was far less dramatic. All proven cases of IA, including 23 cases confirmed after autopsy only, had been detected before death, although serial sampling appeared to be necessary to maximize detection. The excellent sensitivity and negative predictive value makes this approach suitable for clinical decision making. Unfortunately, given the species-specificity of the assay, some emerging non-Aspergillus mycoses were not detected. In conclusion, serial screening for GM, complemented by appropriate imaging techniques, is a sensitive and noninvasive tool for the early diagnosis of IA in high-risk adult hematology patients.