The diagnosis of invasive and noninvasive pulmonary aspergillosis by serum and bronchoalveolar lavage fluid galactomannan assay

COVID-19 and Fungal Infections: A Double Debacle

Fungal infections remain hardly treatable because of unstandardized diagnostic tests, limited antifungal armamentarium, and more specifically, potential toxic interactions between antifungals and immunosuppressants used during anti-inflammatory therapies, such as those set up in critically ill COVID-19 patients. Taking into account pre-existing difficulties in treating vulnerable COVID-19 patients, any co-occurrence of infectious diseases like fungal infections constitutes a double debacle for patients, healthcare experts, and the public economy. Since the first appearance of SARS-CoV-2, a significant rise in threatening fungal co-infections in COVID-19 patients has been testified in the scientific literature. Better management of fungal infections in COVID-19 patients is, therefore, a priority and requires highlighting common risk factors, relationships with immunosuppression, as well as challenges in fungal diagnosis and treatment. The present review attempts to highlight these aspects in the three most identified causative agents of fungal co-infections in COVID-19 patients: Aspergillus, Candida, and Mucorales species.

The role of pentraxin3 in plasma and bronchoalveolar lavage fluid in COPD patients with invasive pulmonary aspergillosis

Background

The use of galactomannan (GM) testing in plasma and bronchoalveolar lavage fluid (BALF) has improved the diagnosis of invasive pulmonary aspergillosis (IPA) in patients with chronic obstructive pulmonary disease (COPD); however, the high false-positive rate leads to overdiagnosis. Pentraxin 3 (PTX3) as an indicator of inflammation plays an important role in resistance to Aspergillus infections. This study aimed to investigate the diagnostic value of PTX3 for diagnosing IPA with COPD.

Methods

We retrospectively collected data on patients with suspected COPD and IPA who had been hospitalized in the Third Affiliated Hospital of Soochow University between September 2017 and November 2020. PTX3 and GM were measured using enzyme-linked immunosorbent assays.

Results

A total of 165 patients were included in the study, of whom 35 had confirmed or probable IPA. The remaining 130 patients served as controls. The median plasma and BALF PTX3 levels were significantly higher in patients with IPA than in control patients (3.74 ng/mL vs. 1.29 ng/mL, P < 0.001; and 3.88 ng/mL vs. 1.58 ng/mL, P < 0.001 in plasma and BALF, respectively). The plasma GM, plasma PTX3, BALF GM, and BALF PTX3 assays had sensitivities of 60.0%, 77.1%, 78.6%, and 89.3%, respectively, and specificities of 73.8%, 69.2%, 80.7%, and 77.1%, respectively. The sensitivity of PTX3 in plasma and BALF was higher than that of GM. However, the specificity of PTX3 and GM did not differ significantly between the IPA group and the control group. The specificity of the assays for the diagnosis of IPA was > 90% in patients who were PTX3-positive and GM-positive in plasma and BALF.

Conclusions

BALF and plasma PTX3 levels were significantly higher in COPD patients with IPA. The sensitivity of PTX3 was superior to that of GM for diagnosing IPA in patients with COPD. The combination of GM and PTX3 is useful for the diagnosis of IPA in patients with COPD.

Dynamic monitor of CT scan within short interval in invasive pulmonary aspergillosis for nonneutropenic patients: a retrospective analysis in two centers

Background

In nonneutropenic patients with underlying respiratory diseases (URD), invasive pulmonary aspergillosis (IPA) is a life-threatening disease. Yet establishing early diagnosis in those patients remains quite a challenge.

Methods

A retrospective series of nonneutropenic patients with probable or proven IPA were reviewed from January 2014 to May 2018 in Department of Respiratory Medicine of two Chinese hospitals. Those patients were suspected of IPA and underwent lung computed tomography (CT) scans twice within 5–21 days. The items required for IPA diagnosis were assessed by their host factors, mycological findings and CT scans according to the European Organization for Research and Treatment of Cancer (EORTC) and the National Institute of Allergy and Infectious Diseases Mycoses Study Group (MSG) criteria (EORTC/MSG criteria).

Results

Together with the risk factors, mycological findings and nonspecific radiological signs on first CT, ten patients were suspected of IPA. With the appearance of cavities on second CT scan in the following days, all patients met the criteria of probable or possible IPA. Except one patient who refused antifungal treatment, nine patients received timely antifungal treatment and recovered well. One of the nine treated IPA cases was further confirmed by pathology, one was confirmed by biopsy.

Conclusions

Dynamic monitor of CT scan provided specific image evidences for IPA diagnosis. This novel finding might provide a noninvasive and efficient strategy in IPA diagnosis with URD.

How a discerning cytological examination can aid in the diagnosis of infectious diseases: case reports

Infections caused by uncommon and resistant pathogens in unusual sites have been increasingly reported in medical literature. We describe four cases of rare cytological findings and clinical impact for patients. In the first case, Aspergillus sp and Pneumocystis jirovecii were observed in the bronchoalveolar lavage of a patient with severe systemic lupus. In the second and third cases, we describe the presence of Trichomonas sp and Strongyloides sp larvae in samples of pleural and peritoneal fluid, respectively. The fourth report is about a patient with a wrist subcutaneous nodule whose synovial aspiration and cytology revealed the presence of brown septate hyphae. The early identification of the infectious agent in the cytological examination was essential for the introduction and/or re-adaptation of therapy in the four cases described. Patients in this report were immunocompromised with severe comorbidities, conditions often associated with unfavorable clinical outcomes.

Diagnostic Accuracy of Bronchoalveolar Lavage Fluid Galactomannan for Invasive Aspergillosis

Background

The pathogenesis of invasive aspergillosis (IA) is still unknown, but its progression is rapid and mortality rate remains high. Bronchoalveolar lavage fluid (BALF) galactomannan (GM) analysis has been used to diagnose IA. This study is aimed at making an accurate estimate of the whole accuracy of BALF-GM in diagnosing IA.

Methods

After a systematic review of the study, a bivariate meta-analysis was used to summarize the specificity (SPE), the sensitivity (SEN), the positive likelihood ratios (PLR), and the negative likelihood ratios (NLR) of BALF-GM in diagnosing IA. The overall test performance was summarized using a layered summary receiver operating characteristic (SROC) curve. Subgroup analysis was performed to explore the heterogeneity between studies.

Results

A total of 65 studies that are in line with the inclusion criteria were included. The summary estimates of BALF-GM analysis are divided into four categories. The first is the proven+probable vs. possible+no IA, with an SPE, 0.87 (95% CI, 0.85-0.98); SEN, 0.81 (95% CI, 0.76-0.84); PLR, 9.78 (5.78-16.56); and NLR, 0.20 (0.14-0.29). The AUC was 0.94. The BALF-GM test for proven+probable vs. no IA showed SPE, 0.88 (95% CI, 0.87-0.90); SEN, 0.82 (95% CI, 0.78-0.85); PLR, 6.56 (4.93-8.75); and NLR, 0.24 (0.17-0.33). The AUC was 0.93. The BALF-GM test for proven+probable+possible vs. no IA showed SPE, 0.82 (95% CI, 0.79-0.95); SEN, 0.59 (95% CI, 0.55-0.63); PLR, 3.60 (2.07-6.25); and NLR, 0.31 (0.15-0.61). The AUC was 0.86. The analyses for others showed SPE, 0.85 (95% CI, 0.83-0.87); SEN, 0.89 (95% CI, 0.86-0.91); PLR, 6.91 (4.67-10.22); and NLR, 0.18 (0.13-0.26). The AUC was 0.94.

Conclusions

The findings of this BALF-GM test resulted in some impact on the diagnosis of IA. The BALF-GM assay is considered a method for diagnosing IA with high SEN and SPE. However, the patients' underlying diseases may affect the accuracy of diagnosis. When the cutoff is greater than 1, the sensitivity will be higher.

Molecular Detection of Aspergillus in Sputum of Patients with Lower Respiratory Tract Infections

BACKGROUND

Raised incidences of respiratory tract infections due to fungal agents in immunocompetent individuals are a cause of concern due to the unavailability of rapid diagnostic methods.

MATERIALS AND METHODS

Sputum and serum samples were collected from patients having lower respiratory tract infections (LRTIs), serum samples were screened for the presence of anti Aspergillus antibodies and sputum samples were homogenized and processed for identification of Aspergillus by conventional methods and further subjected to polymerase chain reaction (PCR) using genus-specific ITS 4-5 primers.

RESULTS

PCR identified Aspergillus in 28% sputum samples, which was high as compared to conventional methods.

CONCLUSION

Simple conventional PCR technique proves to be useful screening in for early identification of Aspergillus colonization in patients with LRTI, which can prevent irreversible damage in their lungs by fungal invasion.

Candida in the Respiratory Tract Potentially Triggers Galactomannan Positivity in Nonhematological Patients

BAL fluid samples from critically ill patients shared a rate of 29% false-positive galactomannan results. We aimed to determine whether Candida species abundance in BAL fluid causes galactomannan (GM) positivity. A total of 89 Candida culture-positive BAL fluid samples from patients without suspicion of invasive aspergillosis (IA) were analyzed. GM results were correlated with Candida species abundance, Candida species quantity, and patient data. Candida species quantities of ≥10⁴/ml and Candida glabrata abundance were significantly associated with positive GM results. The added diagnostic value of GM in BAL fluid for diagnosing IA in critically ill patients is limited.

False-positive Candida and Aspergillus antigen testing in recipients of allogeneic haematopoietic cell transplantation due to administration of parenteral nutrition and fixed combinations of piperacillin-tazobactam

False positivity of antigen immunoassays used as an early diagnostic tool to detect invasive fungal infections is known. Interpretation of the assay needs the identification of sources which could affect the specificity of the test. We focused on the influence of parenteral nutrition (PN) and piperacillin-tazobactam (TZP) on fungal immunoassays. Measurable amounts of Candida antigen mannan were detected in several compounds of PN and TZP in a previous in vitro study. In the current study, 84 patients undergoing allogeneic haematopoietic cell transplantation receiving either TZP, PN or both were monitored with Aspergillus and Candida antigen assay. Six patients were analysed closer in a kinetic analysis with more frequent blood sampling to detect mannan. PN in diverse compositions as well as TZP did not increase significantly the amount of mannan and the Aspergillus antigen in serum. We could not confirm the positive results of the in vitro study. Physicians should be aware that mannan antigenemia due to drug infusion could be a transient issue and should be considered in the interpretation of fungal immunoassays, although we could not find clinically relevant effects on mannan levels.

Galactomannan detection in broncho-alveolar lavage fluid for invasive aspergillosis in immunocompromised patients

BACKGROUND

Invasive aspergillosis (IA) is a life-threatening opportunistic mycosis that occurs in some people with a compromised immune system. The serum galactomannan enzyme-linked immunosorbent assay (ELISA) rapidly gained widespread acceptance as part of the diagnostic work-up of a patient suspected of IA. Due to its non-invasive nature, it can be used as a routine screening test. The ELISA can also be performed on bronchoalveolar lavage (BAL), allowing sampling of the immediate vicinity of the infection. The invasive nature of acquiring BAL, however, changes the role of the galactomannan test significantly, for example by precluding its use as a routine screening test.

OBJECTIVES

To assess the diagnostic accuracy of galactomannan detection in BAL for the diagnosis of IA in people who are immunocompromised, at different cut-off values for test positivity, in accordance with the Cochrane Diagnostic Test Accuracy Handbook.

SEARCH METHODS

We searched three bibliographic databases including MEDLINE on 9 September 2016 for aspergillosis and galactomannan as text words and subject headings where appropriate. We checked reference lists of included studies for additional studies.

SELECTION CRITERIA

We included cohort studies that examined the accuracy of BAL galactomannan for the diagnosis of IA in immunocompromised patients if they used the European Organization for Research and Treatment of Cancer/Invasive Fungal Infections Cooperative Group and the National Institute of Allergy and Infectious Diseases Mycoses Study Group (EORTC/MSG) classification as reference standard.

DATA COLLECTION AND ANALYSIS

Two review authors assessed study quality and extracted data. Quality Assessment of Diagnostic Accuracy Studies-2 (QUADAS-2) was used for quality assessment.

MAIN RESULTS

We included 17 studies in our review. All studies except one had a high risk of bias in two or more domains. The diagnostic performance of an optical density index (ODI) of 0.5 as cut-off value was reported in 12 studies (with 1123 patients). The estimated sensitivity was 0.88 (95% confidence interval (CI) 0.75 to 1.00) and specificity 0.81 (95% CI 0.71 to 0.91). The performance of an ODI of 1.0 as cut-off value could be determined in 11 studies (with 648 patients). The sensitivity was 0.78 (95% CI 0.61 to 0.95) and specificity 0.93 (95% CI 0.87 to 0.98). At a cut-off ODI of 1.5 or higher, the heterogeneity in specificity decreased significantly and was invariably >90%.

AUTHORS' CONCLUSIONS

The optimal cut-off value depends on the local incidence and clinical pathway. At a prevalence of 12% a hypothetical population of 1000 patients will consist of 120 patients with IA. At a cut-off value of 0.5 14 patients with IA will be missed and there will be 167 patients incorrectly diagnosed with IA. If we use the test at a cut-off value of 1.0, we will miss 26 patients with IA. And there will be 62 patients incorrectly diagnosed with invasive aspergillosis. The populations and results were very heterogeneous. Therefore, interpretation and extrapolation of these results has to be performed with caution. A test result of 1.5 ODI or higher appears a strong indicator of IA.

Galactomannan in Bronchoalveolar Lavage Fluid for Diagnosis of Invasive Pulmonary Aspergillosis with Nonneutropenic Patients

Background

We evaluated the utility of galactomannan (GM) in bronchoalveolar lavage fluid (BALF) for the diagnosis of invasive pulmonary aspergillosis (IPA) in nonneutropenic patients.

Methods

A total of 183 patients were included in the final analysis. Bronchoscopies and the detection of GM in BALF were all performed on them.

Results

Ten cases of IPA were diagnosed. ROC data demonstrated that, for diagnosing IPA, an optimal cutoff value for GM in BALF of 0.76 yielded a sensitivity of 100.0% and a specificity of 76.2%. Symptoms and radiological findings had no significant difference between proven or probable IPA group and non-IPA group. In our case-control analysis, although nine patients with false-positive results received treatment with Piperacillin/tazobactam, there was no significant difference between case and control group.

Conclusions

BALF GM detection is a valuable adjunctive diagnostic tool. Our retrospective study suggests that the optimal value of GM detection in BALF is 0.76 in nonneutropenic patients.

Performance of serum galactomannan in patients with allergic bronchopulmonary aspergillosis

Few studies have evaluated the performance of serum galactomannan (GM) in patients with allergic bronchopulmonary aspergillosis (ABPA). Herein, we analyse the diagnostic performance of serum GM in ABPA. Consecutive subjects with ABPA and asthma underwent GM estimation using the Platelia assay (Bio-Rad Laboratories). An optical density index of >0.5 was considered positive. One hundred and twenty subjects (70 ABPA, 50 asthma) with a mean (SD) age of 33.0 (13.1) were included in the study. The serum GM antigen was positive in 18 (25.7%) subjects with ABPA compared to 9 (18%) subjects with asthma without ABPA (P = 0.32). The sensitivity of the serum GM antigen test in patients with ABPA was 25.7% [95% confidence intervals (CI), 16-38] while the specificity was 82% (95% CI, 69-91). The positive and negative predictive values were 66.7% (95% CI, 46-84%) and 44.1% (95% CI, 34-55), respectively. The area under the ROC curve was 0.54 (95% CI, 0.44-0.64). The sensitivity increased and the specificity decreased with decreasing the serum GM cutoff, and vice versa. The results of this study suggest that serum GM estimation has a limited role in the diagnostic workup of patients with ABPA.