PCR diagnosis of Pneumocystis pneumonia: a bivariate meta-analysis

Polymerase Chain Reaction on Respiratory Tract Specimens of Immunocompromised Patients to Diagnose Pneumocystis Pneumonia: A Systematic Review and Meta-analysis

BACKGROUND

This meta-analysis examines the comparative diagnostic performance of polymerase chain reaction (PCR) for the diagnosis of Pneumocystis pneumonia (PCP) on different respiratory tract samples, in both human immunodeficiency virus (HIV) and non-HIV populations.

METHODS

A total of 55 articles met inclusion criteria, including 11 434 PCR assays on respiratory specimens from 7835 patients at risk of PCP. QUADAS-2 tool indicated low risk of bias across all studies. Using a bivariate and random-effects meta-regression analysis, the diagnostic performance of PCR against the European Organisation for Research and Treatment of Cancer-Mycoses Study Group definition of proven PCP was examined.

RESULTS

Quantitative PCR (qPCR) on bronchoalveolar lavage fluid provided the highest pooled sensitivity of 98.7% (95% confidence interval [CI], 96.8%-99.5%), adequate specificity of 89.3% (95% CI, 84.4%-92.7%), negative likelihood ratio (LR-) of 0.014, and positive likelihood ratio (LR+) of 9.19. qPCR on induced sputum provided similarly high sensitivity of 99.0% (95% CI, 94.4%-99.3%) but a reduced specificity of 81.5% (95% CI, 72.1%-88.3%), LR- of 0.024, and LR+ of 5.30. qPCR on upper respiratory tract samples provided lower sensitivity of 89.2% (95% CI, 71.0%-96.5%), high specificity of 90.5% (95% CI, 80.9%-95.5%), LR- of 0.120, and LR+ of 9.34. There was no significant difference in sensitivity and specificity of PCR according to HIV status of patients.

CONCLUSIONS

On deeper respiratory tract specimens, PCR negativity can be used to confidently exclude PCP, but PCR positivity will likely require clinical interpretation to distinguish between colonization and active infection, partially dependent on the strength of the PCR signal (indicative of fungal burden), the specimen type, and patient population tested.

Current Diagnostic Techniques for Pneumonia: A Scoping Review

Community-acquired pneumonia is one of the most lethal infectious diseases, especially for infants and the elderly. Given the variety of causative agents, the accurate early detection of pneumonia is an active research area. To the best of our knowledge, scoping reviews on diagnostic techniques for pneumonia are lacking. In this scoping review, three major electronic databases were searched and the resulting research was screened. We categorized these diagnostic techniques into four classes (i.e., lab-based methods, imaging-based techniques, acoustic-based techniques, and physiological-measurement-based techniques) and summarized their recent applications. Major research has been skewed towards imaging-based techniques, especially after COVID-19. Currently, chest X-rays and blood tests are the most common tools in the clinical setting to establish a diagnosis; however, there is a need to look for safe, non-invasive, and more rapid techniques for diagnosis. Recently, some non-invasive techniques based on wearable sensors achieved reasonable diagnostic accuracy that could open a new chapter for future applications. Consequently, further research and technology development are still needed for pneumonia diagnosis using non-invasive physiological parameters to attain a better point of care for pneumonia patients.

Application value of metagenomic next-generation sequencing in hematological patients with high-risk febrile neutropenia

Background

Metagenomic next-generation sequencing (mNGS) is a novel non-invasive and comprehensive technique for etiological diagnosis of infectious diseases. However, its practical significance has been seldom reported in the context of hematological patients with high-risk febrile neutropenia, a unique patient group characterized by neutropenia and compromised immune responses.

Methods

This retrospective study evaluated the results of plasma cfDNA sequencing in 164 hematological patients with high-risk febrile neutropenia. We assessed the diagnostic efficacy and clinical impact of mNGS, comparing it with conventional microbiological tests.

Results

mNGS identified 68 different pathogens in 111 patients, whereas conventional methods detected only 17 pathogen types in 36 patients. mNGS exhibited a significantly higher positive detection rate than conventional methods (67.7% vs. 22.0%, P < 0.001). This improvement was consistent across bacterial (30.5% vs. 9.1%), fungal (19.5% vs. 4.3%), and viral (37.2% vs. 9.1%) infections (P < 0.001 for all comparisons). The anti-infective treatment strategies were adjusted for 51.2% (84/164) of the patients based on the mNGS results.

Conclusions

mNGS of plasma cfDNA offers substantial promise for the early detection of pathogens and the timely optimization of anti-infective therapies in hematological patients with high-risk febrile neutropenia.

Clinical performance of metagenomic next-generation sequencing for diagnosis of invasive fungal disease after hematopoietic cell transplant

Background

Timely diagnosis and appropriate antifungal therapy are critical for improving the prognosis of patients with invasive fungal disease (IFD) after hematopoietic stem cell transplantation (HSCT). We evaluated the performance of metagenomic next-generation sequencing (mNGS) and conventional microbiological testing (CMT), as well as the diagnosis, therapeutic management, and outcomes of IFD after HSCT.

Methods

We retrospectively studied 189 patients who underwent HSCT and were considered at risk for IFD. In total, 46 patients with IFD were enrolled in this study. The IFD consensus was followed for classifying IFD incidents.

Results

Forty-six patients were diagnosed with proven/probable (n = 12), possible (n = 27), and undefined (n = 7) IFD. Aspergillus was the most commonly detected fungal genus. Mucormycosis was found in 15 patients; two had Aspergillus, and one had Candida infections. Compared to CMT, mNGS significantly reduced the time required to identify pathogens (P = 0.0016). mNGS had a much higher sensitivity than CMT (84.78% vs. 36.96%; P < 0.0001). A total of 76.09% of patients received antifungal prophylaxis during fungal infections. All Pneumocystis infections occurred later than 100 days after transplantation. Among patients with Pneumocystis infection, 71.43% occurred following sulfonamide withdrawal, and subsequent treatment with sulfonamide alone or in combination with other drugs was effective. Based on the empirical antifungal treatment, the dosages, modes of administration, frequency of administration, or antifungal of 55.26% of the patients were changed according to the mNGS results. The 4-year overall survival rate of patients diagnosed with IFD after transplantation was 71.55% (95% CI, 55.18%-85.82%). Hypoproteinemia and corticosteroid use are independent risk factors for IFD.

Conclusion

mNGS, which has a high sensitivity and a short detection time, aids in the diagnosis and prognosis of pathogenic fungi. As a powerful technology, mNGS can influence treatment decisions in patients with IFD following HSCT.

Pneumocystis jirovecii pneumonia in people living with HIV: a review

Pneumocystis jirovecii is a ubiquitous opportunistic fungus that can cause life-threatening pneumonia. People with HIV (PWH) who have low CD4 counts are one of the populations at the greatest risk of Pneumocystis jirovecii pneumonia (PCP). While guidelines have approached the diagnosis, prophylaxis, and management of PCP, the numerous studies of PCP in PWH are dominated by the 1980s and 1990s. As such, most studies have included younger male populations, despite PCP affecting both sexes and a broad age range. Many studies have been small and observational in nature, with an overall lack of randomized controlled trials. In many jurisdictions, and especially in low- and middle-income countries, the diagnosis can be challenging due to lack of access to advanced and/or invasive diagnostics. Worldwide, most patients will be treated with 21 days of high-dose trimethoprim sulfamethoxazole, although both the dose and the duration are primarily based on historical practice. Whether treatment with a lower dose is as effective and less toxic is gaining interest based on observational studies. Similarly, a 21-day tapering regimen of prednisone is used for patients with more severe disease, yet other doses, other steroids, or shorter durations of treatment with corticosteroids have not been evaluated. Now with the widespread availability of antiretroviral therapy, improved and less invasive PCP diagnostic techniques, and interest in novel treatment strategies, this review consolidates the scientific body of literature on the diagnosis and management of PCP in PWH, as well as identifies areas in need of more study and thoughtfully designed clinical trials.

Pneumocystis Pneumonia After Allogeneic Hematopoietic Cell Transplantation: A Case-Control Study on Epidemiology and Risk Factors on Behalf of the Infectious Diseases Working Party of the European Society for Blood and Marrow Transplantation

Pneumocystis pneumonia (PCP) is a life-threatening complication after allogeneic hematopoietic cell transplantation (allo-HCT). However, allo-HCT procedures have evolved toward older patients, unrelated donors, and reduced-intensity conditioning, possibly modifying the risks. Polymerase chain reaction (PCR), widely used nowadays, is more sensitive than microscopy diagnostic methods. This study aimed to assess the factors associated with PCP in allo-HCT recipients within 2 years of HCT and managed according to current procedures. This multicenter, nested case-control study included PCP cases diagnosed by PCR, cytology, or immunofluorescence on bronchoalveolar lavage fluid between 2016 and 2018. Two controls per case were selected from the ProMISe registry and matched for the center, transplant date, and underlying disease. Fifty-two cases and 104 controls were included among the 5452 patients who underwent allo-HCT in the participating centers. PCP occurred at a median of 11.5 months after transplantation. The mortality rate was 24% on day 30 after the PCP diagnosis and 37% on day 90. The clinical presentation and mortality rates of the 24 patients diagnosed using only PCR were not different from those diagnosed with microscopy methods. Our study demonstrates a substantial incidence of, and mortality from, PCP, after allogeneic HCT despite well-established prophylactic approaches. In our experience, PCP nowadays occurs later after transplant than previously reported, justifying the prolongation of prophylaxis after six months in many cases. Allo-HCT recipients diagnosed with PCR as the only PCP marker should benefit from specific treatment as for other patients.

Computed tomography-based radiomics improves non-invasive diagnosis of Pneumocystis jirovecii pneumonia in non-HIV patients: a retrospective study

BACKGROUND

Pneumocystis jirovecii pneumonia (PCP) could be fatal to patients without human immunodeficiency virus (HIV) infection. Current diagnostic methods are either invasive or inaccurate. We aimed to establish an accurate and non-invasive radiomics-based way to identify the risk of PCP infection in non-HIV patients with computed tomography (CT) manifestation of pneumonia.

METHODS

This is a retrospective study including non-HIV patients hospitalized for suspected PCP from January 2010 to December 2022 in one hospital. The patients were randomized in a 7:3 ratio into training and validation cohorts. Computed tomography (CT)-based radiomics features were extracted automatically and used to construct a radiomics model. A diagnostic model with traditional clinical and CT features was also built. The area under the curve (AUC) were calculated and used to evaluate the diagnostic performance of the models. The combination of the radiomics features and serum β-D-glucan levels was also evaluated for PCP diagnosis.

RESULTS

A total of 140 patients (PCP: N = 61, non-PCP: N = 79) were randomized into training (N = 97) and validation (N = 43) cohorts. The radiomics model consisting of nine radiomic features performed significantly better (AUC = 0.954; 95% CI: 0.898-1.000) than the traditional model consisting of serum β-D-glucan levels (AUC = 0.752; 95% CI: 0.597-0.908) in identifying PCP (P = 0.002). The combination of radiomics features and serum β-D-glucan levels showed an accuracy of 95.8% for identifying PCP infection (positive predictive value: 95.7%, negative predictive value: 95.8%).

CONCLUSIONS

Radiomics showed good diagnostic performance in differentiating PCP from other types of pneumonia in non-HIV patients. A combined diagnostic method including radiomics and serum β-D-glucan has the potential to provide an accurate and non-invasive way to identify the risk of PCP infection in non-HIV patients with CT manifestation of pneumonia.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT05701631).

Pneumocystis jirovecii with high probability detected in bronchoalveolar lavage fluid of chemotherapy-related interstitial pneumonia in patients with lymphoma using metagenomic next-generation sequencing technology

BACKGROUND

Previous studies achieved low microbial detection rates in lymphoma patients with interstitial pneumonia (IP) after chemotherapy. However, the metagenomic next-generation sequencing (mNGS) is a comprehensive approach that is expected to improve the pathogen identification rate. Thus far, reports on the use of mNGS in lymphoma patients with chemotherapy-related IP remain scarce. In this study, we summarized the microbial detection outcomes of lymphoma patients with chemotherapy-related IP through mNGS testing of bronchoalveolar lavage fluid (BALF).

METHODS

Fifteen lymphoma patients with chemotherapy-related IP were tested for traditional laboratory microbiology, along with the mNGS of BALF. Then, the results of mNGS and traditional laboratory microbiology were compared.

RESULTS

Of the 15 enrolled patients, 11 received rituximab and 8 were administered doxorubicin hydrochloride liposome. The overall microbial yield was 93.3% (14/15) for mNGS versus 13.3% (2/15) for traditional culture methods (P ≤ 0.05). The most frequently detected pathogens were Pneumocystis jirovecii (12/15, 80%), Cytomegalovirus (4/15, 26.7%), and Epstein-Barr virus (3/15, 20%). Mixed infections were detected in 10 cases. Five patients recovered after the treatment with antibiotics alone without glucocorticoids.

CONCLUSION

Our findings obtained through mNGS testing of BALF suggested a high microbial detection rate in lymphoma patients with IP after chemotherapy. Notably, there was an especially high detection rate of Pneumocystis jirovecii. The application of mNGS in patients with chemotherapy-related IP was more sensitive.

An Evaluation of the OLM PneumID Real-Time Polymerase Chain Reaction to Aid in the Diagnosis of Pneumocystis Pneumonia

BACKGROUND

The use of the PCR to aid in the diagnosis of Pneumocystis pneumonia (PcP) has demonstrated excellent clinical performance, as evidenced through various systematic reviews and meta-analyses, yet there are concerns over the interpretation of positive results due to the potential presence of Pneumocystis colonization of the airways. While this can be overcome by applying designated positivity thresholds to PCR testing, the shear number of assays described limits the development of a universal threshold. Commercial assays provide the opportunity to overcome this problem, provided satisfactory performance is determined through large-scale, multi-centre evaluations.

METHODS

Retrospective case/control and consecutive cohort performance evaluations of the OLM PneumID real-time PCR assay were performed on DNA eluates from a range of samples sent from patients where "in-house" PCR had been performed as part of routine diagnostic testing. The clinical performance of the PneumID assay was determined before including it in a diagnostic algorithm to provide the probability of PcP (dependent on diagnostic evidence).

RESULTS

After being used to test 317 patients (32 with PcP), the overall performance of the PneumID assay was found to be excellent (Sensitivity/Specificity: 96.9%/95.1%). False positivity could be removed by applying a threshold specific to sample type (<33.1 cycles for BAL fluid; <37.0 cycles for throat swabs), whereas considering any positive respiratory samples as significant generated 100% sensitivity, making absolute negativity sufficient to exclude PcP. Incorporating the PneumID assay into diagnostic algorithms alongside (1-3)-β-D-Glucan testing provided high probabilities of PcP (up to 85.2%) when both were positive and very low probabilities (<1%) when both were negative.

CONCLUSIONS

The OLM PneumID qPCR provides a commercial option for the accurate diagnosis of PcP, generating excellent sensitivity and specificity, particularly when testing respiratory specimens. The combination of PcP PCR with serum (1-3)-β-D-Glucan provides excellent clinical utility for diagnosing PcP.

The SSS revolution in fungal diagnostics: speed, simplicity and sensitivity

INTRODUCTION

Fungal disease has historically presented a diagnostic challenge due to its often non-specific clinical presentations, relative infrequency and reliance on insensitive and time-intensive fungal culture.

SOURCES OF DATA

We present the recent developments in fungal diagnostics in the fields of serological and molecular diagnosis for the most clinically relevant pathogens; developments that have the potential to revolutionize fungal diagnosis through improvements in speed, simplicity and sensitivity. We have drawn on a body of evidence including recent studies and reviews demonstrating the effectiveness of antigen and antibody detection and polymerase chain reaction (PCR) in patients with and without concurrent human immunodeficiency virus infection.

AREAS OF AGREEMENT

This includes recently developed fungal lateral flow assays, which have a low cost and operator skill requirement that give them great applicability to low-resource settings. Antigen detection for Cryptococcus, Histoplasma and Aspergillus spp. are much more sensitive than culture. PCR for Candida spp., Aspergillus spp., Mucorales and Pneumocystis jirovecii is more sensitive than culture and usually faster.

AREAS OF CONTROVERSY

Effort must be made to utilize recent developments in fungal diagnostics in clinical settings outside of specialist centres and integrate their use into standard medical practice. Given the clinical similarities of the conditions and frequent co-infection, further study is required into the use of serological and molecular fungal tests, particularly in patients being treated for tuberculosis.

GROWING POINTS

Further study is needed to clarify the utility of these tests in low-resource settings confounded by a high prevalence of tuberculosis.

AREAS TIMELY FOR DEVELOPING RESEARCH

The diagnostic utility of these tests may require revision of laboratory work flows, care pathways and clinical and lab coordination, especially for any facility caring for the immunosuppressed, critically ill or those with chronic chest conditions, in whom fungal disease is common and underappreciated.

The Diagnostic Accuracy of Metagenomic Next-Generation Sequencing in Diagnosing Pneumocystis Pneumonia: A Systemic Review and Meta-analysis

Background

Pneumocystis pneumonia (PCP) is a growing concern as the immunocompromised population expands. Current laboratory approaches are limited. This systematic review aimed to evaluate metagenomic next-generation sequencing (MNGS) tests' performance in detecting PCP.

Methods

Five databases were searched through December 19, 2022, to identify original studies comparing MNGS with clinically diagnosed PCP. To assess the accuracy, symmetric hierarchical summary receiver operating characteristic models were used.

Results

Eleven observational studies reporting 1442 patients (424 with PCP) were included. Six studies focused exclusively on recipients of biologic immunosuppression (none with HIV-associated immunosuppression). Six were exclusively on bronchoalveolar lavage, while 1 was on blood samples. The sensitivity of MGNS was 0.96 (95% CI, 0.90-0.99), and specificity was 0.96 (95% CI, 0.92-0.98), with negative and positive likelihood ratios of 0.02 (95% CI, 0.01-0.05) and 19.31 (95% CI, 10.26-36.36), respectively. A subgroup analysis of studies exclusively including bronchoalveolar lavage (BAL) and blood samples demonstrated a sensitivity of 0.94 (95% CI, 0.78-0.99) and 0.93 (95% CI, 0.80-0.98) and a specificity of 0.96 (95% CI, 0.88-0.99) and 0.98 (95% CI, 0.76-1.00), respectively. The sensitivity analysis on recipients of biologic immunosuppression showed a sensitivity and specificity of 0.96 (95% CI, 0.90-0.98) and 0.94 (95% CI, 0.84-0.98), respectively. The overall confidence in the estimates was low.

Conclusions

Despite the low certainty of evidence, MNGS detects PCP with high sensitivity and specificity. This also applies to recipients of biologic immunosuppression and tests performed exclusively on blood samples without the need for BAL. Further studies are required in individuals with HIV-associated immunosuppression.

An update on current and novel molecular diagnostics for the diagnosis of invasive fungal infections

BACKGROUND

Invasive fungal infections cause millions of infections annually, but diagnosis remains challenging. There is an increased need for low-cost, easy to use, highly sensitive and specific molecular assays that can differentiate between colonized and pathogenic organisms from different clinical specimens.

AREAS COVERED

We reviewed the literature evaluating the current state of molecular diagnostics for invasive fungal infections, focusing on current and novel molecular tests such as polymerase chain reaction (PCR), digital PCR, high-resolution melt (HRM), and metagenomics/next generation sequencing (mNGS).

EXPERT OPINION

PCR is highly sensitive and specific, although performance can be impacted by prior/concurrent antifungal use. PCR assays can identify mutations associated with antifungal resistance, non-Aspergillus mold infections, and infections from endemic fungi. HRM is a rapid and highly sensitive diagnostic modality that can identify a wide range of fungal pathogens, including down to the species level, but multiplex assays are limited and HRM is currently unavailable in most healthcare settings, although universal HRM is working to overcome this limitation. mNGS offers a promising approach for rapid and hypothesis-free diagnosis of a wide range of fungal pathogens, although some drawbacks include limited access, variable performance across platforms, the expertise and costs associated with this method, and long turnaround times in real-world settings.

Clinical features and diagnostic value of metagenomic next -generation sequencing in five cases of non-HIV related Pneumocystis jirovecii pneumonia in children

Background

Pneumocystis jirovecii (PJ) is an opportunistic pathogenic fungus, and PJ pneumonia (PJP) is a commonly problem in HIV-positive patients. While PJP is not caused by HIV, it generally advances rapidly and can quickly lead to severe respiratory failure. To improve pediatricians’ understanding of the condition and aid early accurate diagnoses and therapy, we examined the clinical characteristics of five instances of non-HIV related PJP (NH-PJP) in children and the efficacy of metagenomic next-generation sequencing (mNGS) in its diagnosis.

Methods

From January 2020 to June 2022, five children with NH-PJP were admitted to the PICU of the First Affiliated Hospital of Zhengzhou University. We retrospectively summarize the clinical presentation, previous histories, routine laboratory findings, treatment, outcome of regression, and results of mNGS in these five children.

Results

Five male children between the ages of 11 months and 14 years had an acute onset on NH-PJP, three of the children had chest tightness after activity, shortness of breath and paroxysmal dry cough, — and two had high fever and dry cough. All five of the children had several flocculent high-density pictures in both lungs at the beginning of the disease, and lung auscultation revealed coarse breath sounds in both lungs, one of which was accompanied by a modest quantity of dry rales. PJ nuclear sequences were found in one patient and four patients’ blood and alveolar lavage fluid. All five children were treated with Trimethoprim-sulfamethoxazole (TMP-SMX) in combination with Caspofungin and corresponding symptomatic treatment. Four patients were cured and one patient died.

Conclusion

Children commonly encounter an initial exposure to NH-PJP, which manifests as a high fever, dry cough, chest discomfort, dyspnea that worsens over time, fast disease progression, and a high death rate. The clinical presentation of children with PJ infection should be taken into consideration along with the results for diagnose. mNGS has higher sensitivity and a shorter detection period compared to identification of PJP.

The Use of Host Biomarkers for the Management of Invasive Fungal Disease

Invasive fungal disease (IFD) causes severe morbidity and mortality, and the number of IFD cases is increasing. Exposure to opportunistic fungal pathogens is inevitable, but not all patients with underlying diseases increasing susceptibility to IFD, develop it. IFD diagnosis currently uses fungal biomarkers and clinical risk/presentation to stratify high-risk patients and classifies them into possible, probable, and proven IFD. However, the fungal species responsible for IFD are highly diverse and present numerous diagnostic challenges, which culminates in the empirical anti-fungal treatment of patients at risk of IFD. Recent studies have focussed on host-derived biomarkers that may mediate IFD risk and can be used to predict, and even identify IFD. The identification of novel host genetic variants, host gene expression changes, and host protein expression (cytokines and chemokines) associated with increased risk of IFD has enhanced our understanding of why only some patients at risk of IFD actually develop disease. Furthermore, these host biomarkers when incorporated into predictive models alongside conventional diagnostic techniques enhance predictive and diagnostic results. Once validated in larger studies, host biomarkers associated with IFD may optimize the clinical management of populations at risk of IFD. This review will summarise the latest developments in the identification of host biomarkers for IFD, their use in predictive modelling and their potential application/usefulness for informing clinical decisions.

A comprehensive clinical guide for Pneumocystis jirovecii pneumonia: a missing therapeutic target in HIV-uninfected patients

INTRODUCTION

Pneumocystis jirovecii is an opportunistic, human-specific fungus that causes Pneumocystis pneumonia (PCP). PCP symptoms are nonspecific. A patient with P. jirovecii and another lung infection faces a diagnostic challenge. It may be difficult to determine which of these agents is responsible for the clinical symptoms, preventing effective treatment. Diagnostic and treatment efforts have been made more difficult by the rising frequency with which coronavirus 2019 (COVID-19) and PCP co-occur.

AREAS COVERED

Herein, we provide a comprehensive review of clinical and pharmacological recommendations along with a literature review of PCP in immunocompromised patients focusing on HIV-uninfected patients.

EXPERT OPINION

PCP may be masked by identifying co-existing pathogens that are not necessarily responsible for the observed infection. Patients with severe form COVID-19 should be examined for underlying immunodeficiency, and co-infections must be considered as co-infection with P. jirovecii may worsen COVID-19's severity and fatality. PCP should be investigated in patients with PCP risk factors who come with pneumonia and suggestive radiographic symptoms but have not previously received PCP prophylaxis. PCP prophylaxis should be explored in individuals with various conditions that impair the immune system, depending on their PCP risk.

The diagnostic value of metagenomic next-generation sequencing for identifying Pneumocystis jirovecii infection in non-HIV immunocompromised patients

Background

Pneumocystis jirovecii pneumonia (PJP) remains an important cause of morbidity and mortality in non-HIV immunocompromised patients especially in transplant recipients. But its diagnosis remains challenging due to the insuffificient performance of conventional methods for diagnosing Pneumocystis jirovecii(P. jirovecii) infection. Therefore, the auxiliary diagnostic function of metagenomics next-generation sequencing (mNGS) in clinical practice is worth of exploring.

Method

34 non-HIV immunocompromised patients who were diagnosed as PJP by clinical manifestations, imaging findings, immune status of the host, and Methenamine silver staining were tested by mNGS from October 2018 to December 2020 in Sichuan Provincial People’s Hospital. The clinical performances of mNGS for P. jirovecii infection diagnosis were also evaluated with genome reads abundance and comparing with other traditional diagnostic methods.

Results

We diagnosed a total of 34 non-HIV PJP patients by the clinical composite diagnosis. Our data shows that, compared with the clinical microbiological test, the detection rate of mNGS for P. jirovecii in non-HIV infected PJP patients is significantly higher than that of Methenamine silver staining and serum 1-3-β-D-glucan. mNGS can be used as an auxiliary diagnostic tool to help diagnosis. The number of reads mapped to the genome of P. jirovecii and the duration of patients from onset to sampling collection were statistically significant between the two groups (Reads>100 and Reads ≤ 100) (8days vs. 23days, p=0.020). In addition, univariate analysis showed that C-reactive protein (15.8mg/L vs.79.56mg/L, p=0.016), lactate dehydrogenase (696U/l vs. 494U/l, p=0.030) and procalcitonin (0.09ng/ml vs. 0.59ng/ml, p=0.028) was also statistically significant between the two groups.

Conclusions

An effective detection rate was achieved in PJP patients using mNGS testing of bronchoalveolar lavage fluid (BALF) or blood. The study also confirmed that the abundance of reads of P. jirovecii is related to the interval between the onset and sample collection. And the inflammation status during simultaneous mNGS detection might determine the abundance of pathogens. Hence, we conclude that the mNGS strategy could benefit disease diagnosis as well as treatment when complicated clinical infections appeared.

Accuracy of Pneumocystis jirovecii Plasma Cell-Free DNA PCR for Noninvasive Diagnosis of Pneumocystis Pneumonia

Pneumocystis pneumonia (PCP) caused by Pneumocystis jirovecii is a serious infection in immunocompromised hosts which requires prompt diagnosis and treatment. The recommended specimen for diagnosis of PCP is bronchoalveolar lavage (BAL) fluid, which is invasive and may not be possible in unstable patients. The aim of this study was to evaluate the accuracy of noninvasive P. jirovecii plasma cell-free DNA (cfDNA) PCR using recently optimized preanalytical and analytical methods. Adult patients undergoing clinical testing for PCP with direct fluorescent antibody stain (DFA), respiratory PCR, and/or β-d-glucan were included in this study. Sensitivity and specificity P. jirovecii plasma cfDNA PCR was determined in PCP suspects categorized as proven and probable. A total of 149 patients were included in this study, of which 10 had proven and 27 had probable PCP. Most patients (95.9%, 143/149) were immunocompromised, including hematological malignancies (30.1%), bone marrow transplant (11.2%), solid organ transplantation (47.6%), and HIV/AIDS (4.2%). P. jirovecii plasma cfDNA PCR showed sensitivity and specificity of 100% (10/10; 95% confidence interval [CI], 69.2 to 100) and 93.4% (127/136; 95% CI, 87.8 to 96.9), and 48.6% (18/37; 95% CI, 31.9 to 65.6) and 99.1% (108/109; 95% CI, 94.9 to 100) in proven and proven/probable cases, respectively. P. jirovecii cell-free DNA PCR was similar in sensitivity but with substantially improved specificity over β-d-glucan (sensitivity, 60.0% [18/30; 95% CI, 40.6 to 77.3]); specificity, 66.7% [22/33; 95% CI, 48.2 to 82.0]) in patients with proven/probable PCP. Plasma cfDNA PCR offers a noninvasive testing option for early and accurate diagnosis of PCP, particularly in patients who cannot tolerate bronchoscopy.

Performance of a Real Time PCR for Pneumocystis jirovecii Identification in Induced Sputum of AIDS Patients: Differentiation between Pneumonia and Colonization

Pneumocystis jirovecii pneumonia (PcP) remains an important cause of morbimortality worldwide and a diagnostic challenge. Conventional methods have low accuracy, hardly discriminating colonization from infection, while some new high-cost or broncho-alveolar lavage-based methods have limited usefulness in developing countries. Quantitative PCR (qPCR) tests may overcome these limitations due to their high accuracy, possibility of automation, and decreasing cost. We evaluated an in-house qPCR targeting the fungus mtSSU gene using induced sputum. Sensitivity of the assay (ten target gene copies/assay) was determined using recombinant plasmids. We prospectively studied 86 AIDS patients with subacute respiratory symptoms in whom PcP was suspected. qPCR results were determined as quantification cycles (Cq) and compared with a qualitative PCR performed in the same IS, serum 1,3-β-D-Glucan assay, and a clinical/laboratory/radiology index for PcP. The qPCR clustered the patients in three groups: 32 with Cq ≤ 31 (qPCR+), 45 with Cq ≥ 33 (qPCR-), and nine with Cq between 31-33 (intermediary), which, combined with the other three analyses, enabled us to classify the groups as having PcP, not P. jirovecii-infected, and P. jirovecii-colonized, respectively. This molecular assay may contribute to improve PcP management, avoiding unnecessary treatments, and our knowledge of the natural history of this infection.

An overview of using fungal DNA for the diagnosis of invasive mycoses

INTRODUCTION

Fungal PCR has undergone considerable standardization and together with the availability of commercial assays, external quality assessment schemes and extensive performance validation data, is ready for widespread use for the screening and diagnosis of invasive fungal disease (IFD).

AREAS COVERED

Drawing on the experience and knowledge of the leads of the various working parties of the Fungal PCR initiative, this review will address general considerations concerning the use of molecular tests for the diagnosis of IFD, before focussing specifically on the technical and clinical aspects of molecular testing for the main causes of IFD and recent technological developments.

EXPERT OPINION

For infections caused by Aspergillus, Candida and Pneumocystis jirovecii, PCR testing is recommended, combination with serological testing will likely enhance the diagnosis of these diseases. For other IFD (e.g. Mucormycosis) molecular diagnostics, represent the only non-classical mycological approach towards diagnoses and continued performance validation and standardization has improved confidence in such testing. The emergence of antifungal resistance can be diagnosed, in part, through molecular testing. Next-generation sequencing has the potential to significantly improve our understanding of fungal phylogeny, epidemiology, pathogenesis, mycobiome/microbiome and interactions with the host, while identifying novel and existing mechanisms of antifungal resistance and novel diagnostic/therapeutic targets.

Clinical Performance of BAL Metagenomic Next-Generation Sequence and Serum (1,3)-β-D-Glucan for Differential Diagnosis of Pneumocystis jirovecii Pneumonia and Pneumocystis jirovecii Colonisation

Background

Differentiating Pneumocystis jirovecii infection from colonisation is crucial for appropriate therapy administration. In this study, we evaluated the performance of bronchoalveolar lavage fluid (BAL) metagenomic next-generation sequencing (mNGS) and serum 1,3-β-D-glucan (BDG) tests in differentiating colonisation and infection with P. jirovecii.

Methods

From January 2018 to March 2021, 47 patients were enrolled in this study at the Hunan Provincial People’s Hospital. The final diagnosis was used as a reference, and cases were classified into the P. jirovecii pneumonia (PJP) group or the P. jirovecii colonisation (PJC) group. Clinical data were recorded. The performances of mNGS and BDG were compared.

Result

The fungal load significantly differed between patients with PJP and PJC, with median reads of 3,215.79 ± 1,797 vs. 5.61 ± 0.88 in the PJP and PJC groups, respectively (P < 0.0001). BDG also significantly differed between the two groups, with a median titre of 233.60 ± 39.65 pg/ml in the PJP group and 68.48 ± 19.21 pg/ml in the PJC group (P = 0.0006). The area under the curve was 0.973 (95%CI: 0.868–1.007) for mNGS of the BAL and 0.879 (95%CI: 0.769–0.989) for the serum BDG. The optimal threshold value for discriminating P. jirovecii infection from colonisation appeared to be 14 reads (sensitivity, 83.3%; specificity, 95.7%; positive likelihood ratio, 19.2) and BDG = 88.6 pg/ml (sensitivity, 79.2%; specificity, 92.9%; positive likelihood ratio, 18.2). No correlation between mNGS reads and the BDG titre was found in mNGS-positive patients (r² = 0.0076, P = 0.583). The levels of lactate dehydrogenase and C-reactive protein were significantly higher in the PJP group than in the PJC group.

Conclusion

BAL mNGS and serum BDG are useful adjunct tests that can assist with differentiating between colonisation and infection of P. jirovecii.

A novel droplet digital polymerase chain reaction for diagnosis of Pneumocystis pneumonia (PCP)-a clinical performance study and survey of sulfamethoxazole-trimethoprim resistant mutations

Objectives To determine the performance of droplet digital polymerase chain reaction (ddPCR) assays in diagnosing Pneumocystis pneumonia (PCP), and to survey the sulfamethoxazole-trimethoprim (SMX-TMP) resistant mutations in our PCP cohort. Methods A prospective study was conducted from January 2017 to June 2018. Adult immunocompromised subjects with pneumonia were enrolled. Bronchoalveolar lavage fluid samples were obtained for standard microscopic testing and ddPCR to quantify the Pneumocystis MSG gene. DHPS and DHFR gene sequencings were performed to detect SMX-TMP resistance. Results Of 54 subjects, 12 had definite PCP, 7 had probable PCP, and 35 were non-PCP. In the PCP cohort, 10 (53%) had HIV infections. Using a cutoff value of ≥ 1.94 copies/µL, the ddPCR exhibited an overall sensitivity of 91.7% (61.5-99.8%) and specificity of 88.1% (74.4-96%). It showed a better performance when different cutoff values were used in subjects with HIV (≥ 1.80 copies/µL) and non-HIV (≥ 4.5 copies/µL). ROC curves demonstrated an AUC of 0.80 (95% CI, 0.56-1.0) for the HIV group, and 0.99 (95% CI, 0.95-1.0) for the non-HIV group. Of 16 PCP samples tested for DHPS- and DHFR-mutations, only DHPS mutations were detected (2). Most of the subjects, including those with DHPS mutations, demonstrated favorable outcomes. Conclusions The ddPCR exhibited a satisfactory diagnostic performance for PCP. Based on very limited data, the treatment outcomes of PCP did not seem to be affected by the DHPS mutations.

Medical and Neurological Management of Brain Tumor Complications

PURPOSE OF REVIEW

The diagnosis of brain tumors often leads to complications that are either related to the tumor itself or the tumor-directed and supportive therapies, increasing the burden on the patients' quality of life and even survival. This article reviews the medical and neurological conditions that commonly complicate the disease course of brain tumors patients.

RECENT FINDINGS

Various mechanisms have been newly identified to be involved in the pathophysiology of seizures and brain edema and can help advance the treatment of such complications. There have also been new developments in the management of thromboembolic disease and cognitive impairment. Medical and neurological complications are being identified more often in brain tumor patients with the improved survival provided by therapeutic advances. Early and proper identification and management of such complications are crucial for a better survival and quality of life.

Non-invasive diagnosis of Pneumocystis jirovecii pneumonia: a systematic review and meta-analysis

BACKGROUND

Pneumocystis jirovecii pneumonia (PCP) is an opportunistic infection commonly affecting immunocompromised people. Diagnosis usually requires invasive techniques to obtain respiratory specimens. Minimally invasive detection tests have been proposed, but their operating characteristics are poorly described.

OBJECTIVES

To systematically review and meta-analyse the performance of minimally invasive PCP detection tests to inform diagnostic algorithms.

DATA SOURCES

Medline, Embase, Cochrane Library (inception to 15 October 2020).

STUDY ELIGIBILITY CRITERIA

Studies of minimally invasive PCP detection tests were included if they contained a minimum of ten PCP cases.

PARTICIPANTS

Adults at risk of PCP.

TESTS

Non-invasive PCP detection tests.

REFERENCE STANDARD

Diagnosis using the combination of clinical and radiographical features with invasive sampling.

ASSESSMENT OF RISK BIAS

Using the QUADAS-2 tool.

METHODS

We used bivariate and, when necessary, univariate analysis models to estimate diagnostic test sensitivity and specificity.

RESULTS

Fifty-two studies were included; most studies (40) comprised exclusively human immunodeficiency virus (HIV) -infected individuals; nine were mixed (HIV and non-HIV), two were non-HIV and one study did not report HIV status. Sampling sites included induced sputum, nasopharyngeal aspirate, oral wash and blood. The four testing modalities evaluated were cytological staining, fluorescent antibody, PCR and lactate dehydrogenase. Induced sputum had the most data available; this modality was both highly sensitive at 99% (95% CI 51%-100%) and specific at 96% (95% CI 88%-99%). Induced sputum cytological staining had moderate sensitivity at 50% (95% CI 39%-61%) and high specificity at 100% (95% CI 100%-100%), as did fluorescent antibody testing with sensitivity 74% (95% CI 62%-87%) and specificity 100% (95% CI 91%-100%).

CONCLUSION

There are several promising minimally invasive PCP diagnostic tests available, some of which may reduce the need for invasive respiratory sampling. Understanding the operating characteristics of these tests can augment current diagnostic strategies and help establish a more confident clinical diagnosis of PCP. Further studies in non-HIV infected populations are needed.

Recognition of Diagnostic Gaps for Laboratory Diagnosis of Fungal Diseases: Expert Opinion from the Fungal Diagnostics Laboratories Consortium (FDLC)

Fungal infections are a rising threat to our immunocompromised patient population, as well as other nonimmunocompromised patients with various medical conditions. However, little progress has been made in the past decade to improve fungal diagnostics. To jointly address this diagnostic challenge, the Fungal Diagnostics Laboratory Consortium (FDLC) was recently created. The FDLC consists of 26 laboratories from the United States and Canada that routinely provide fungal diagnostic services for patient care. A survey of fungal diagnostic capacity among the 26 members of the FDLC was recently completed, identifying the following diagnostic gaps: lack of molecular detection of mucormycosis; lack of an optimal diagnostic algorithm incorporating fungal biomarkers and molecular tools for early and accurate diagnosis of Pneumocystis pneumonia, aspergillosis, candidemia, and endemic mycoses; lack of a standardized molecular approach to identify fungal pathogens directly in formalin-fixed paraffin-embedded tissues; lack of robust databases to enhance mold identification with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry; suboptimal diagnostic approaches for mold blood cultures, tissue culture processing for Mucorales, and fungal respiratory cultures for cystic fibrosis patients; inadequate capacity for fungal point-of-care testing to detect and identify new, emerging or underrecognized, rare, or uncommon fungal pathogens; and performance of antifungal susceptibility testing. In this commentary, the FDLC delineates the most pressing unmet diagnostic needs and provides expert opinion on how to fulfill them. Most importantly, the FDLC provides a robust laboratory network to tackle these diagnostic gaps and ultimately to improve and enhance the clinical laboratory's capability to rapidly and accurately diagnose fungal infections.

Performance of real-time PCR and immunofluorescence assay for diagnosis of Pneumocystis pneumonia in real-world clinical practice

Background

PCR is more sensitive than immunofluorescence assay (IFA) for detection of Pneumocystis jirovecii. However, PCR cannot always distinguish infection from colonization. This study aimed to compare the performance of real-time PCR and IFA for diagnosis of P. jirovecii pneumonia (PJP) in a real-world clinical setting.

Methods

A retrospective cohort study was conducted at a 1,300-bed hospital between April 2017 and December 2018. Patients whose respiratory sample (bronchoalveolar lavage or sputum) were tested by both Pneumocystis PCR and IFA were included. Diagnosis of PJP was classified based on multicomponent criteria. Sensitivity, specificity, 95% confidence intervals (CI), and Cohen's kappa coefficient were calculated.

Results

There were 222 eligible patients. The sensitivity and specificity of PCR was 91.9% (95% CI, 84.0%–96.7%) and 89.7% (95% CI, 83.3%–94.3%), respectively. The sensitivity and specificity of IFA was 7.0% (95% CI, 2.6%–14.6%) and 99.2% (95% CI, 95.6%–100.0%), respectively. The percent agreement between PCR and IFA was 56.7% (Cohen's kappa -0.02). Among discordant PCR-positive and IFA-negative samples, 78% were collected after PJP treatment. Clinical management would have changed in 14% of patients using diagnostic information, mainly based on PCR results.

Conclusions

PCR is highly sensitive compared with IFA for detection of PJP. Combining clinical, and radiological features with PCR is useful for diagnosis of PJP, particularly when respiratory specimens cannot be promptly collected before initiation of PJP treatment.

Diagnosing Pneumocystis jirovecii pneumonia: A review of current methods and novel approaches

Pneumocystis jirovecii can cause life-threatening pneumonia in immunocompromised patients. Traditional diagnostic testing has relied on staining and direct visualization of the life-forms in bronchoalveolar lavage fluid. This method has proven insensitive, and invasive procedures may be needed to obtain adequate samples. Molecular methods of detection such as polymerase chain reaction (PCR), loop-mediated isothermal amplification (LAMP), and antibody-antigen assays have been developed in an effort to solve these problems. These techniques are very sensitive and have the potential to detect Pneumocystis life-forms in noninvasive samples such as sputum, oral washes, nasopharyngeal aspirates, and serum. This review evaluates 100 studies that compare use of various diagnostic tests for Pneumocystis jirovecii pneumonia (PCP) in patient samples. Novel diagnostic methods have been widely used in the research setting but have faced barriers to clinical implementation including: interpretation of low fungal burdens, standardization of techniques, integration into resource-poor settings, poor understanding of the impact of host factors, geographic variations in the organism, heterogeneity of studies, and limited clinician recognition of PCP. Addressing these barriers will require identification of phenotypes that progress to PCP and diagnostic cut-offs for colonization, generation of life-form specific markers, comparison of commercial PCR assays, investigation of cost-effective point of care options, evaluation of host factors such as HIV status that may impact diagnosis, and identification of markers of genetic diversity that may be useful in diagnostic panels. Performing high-quality studies and educating physicians will be crucial to improve the rates of diagnosis of PCP and ultimately to improve patient outcomes.

Consensus Multilocus Sequence Typing Scheme for Pneumocystis jirovecii

Pneumocystis jirovecii is an opportunistic human pathogenic fungus causing severe pneumonia mainly in immunocompromised hosts. Multilocus sequence typing (MLST) remains the gold standard for genotyping of this unculturable fungus. However, the lack of a consensus scheme impedes a global comparison, large scale population studies and the development of a global MLST database. To overcome this problem this study compared all genetic regions (19 loci) currently used in 31 different published Pneumocystis MLST schemes. The most diverse/commonly used eight loci, β-TUB, CYB, DHPS, ITS1, ITS1/2, mt26S and SOD, were further assess for their ability to be successfully amplified and sequenced, and for their discriminatory power. The most successful loci were tested to identify genetically related and unrelated cases. A new consensus MLST scheme consisting of four genetically independent loci: β-TUB, CYB, mt26S and SOD, is herein proposed for standardised P. jirovecii typing, successfully amplifying low and high fungal burden specimens, showing adequate discriminatory power, and correctly identifying suspected related and unrelated isolates. The new consensus MLST scheme, if accepted, will for the first time provide a powerful tool to investigate outbreak settings and undertake global epidemiological studies shedding light on the spread of this important human fungal pathogen.

Development and Evaluation of a Fully Automated Molecular Assay Targeting the Mitochondrial Small Subunit rRNA Gene for the Detection of Pneumocystis jirovecii in Bronchoalveolar Lavage Fluid Specimens

The fungal pathogen Pneumocystis jirovecii causes Pneumocystis pneumonia. Although the mitochondrial large subunit rRNA gene (mtLSU) is commonly used as a PCR target, a mitochondrial small subunit rRNA gene (mtSSU)-targeted MultiCode PCR assay was developed on the fully automated ARIES platform for detection of P. jirovecii in bronchoalveolar lavage fluid specimens in 2.5 hours. The assay showed a limit of detection of 800 copies/mL (approximately equal to 22 organisms/mL), with no cross-reactivity with other respiratory pathogens. Compared with the reference Pneumocystis-specific direct fluorescent antibody assay (DFA) and mtLSU-targeted PCR assay, the new assay demonstrated sensitivity of 96.9% (31/32) and specificity of 94.6% (139/147) in detecting P. jirovecii in 180 clinical bronchoalveolar lavage fluid specimens. This assay was concordant with all DFA-positive samples and all but one mtLSU PCR-positive sample, and detected eight positive samples that were negative by DFA and mtLSU PCR. Receiver operating characteristic curve analysis revealed an area under the curve of 0.98 and a threshold cycle (C_T) cutoff of 39.1 with sensitivity of 90.9% and specificity of 99.3%. The detection of 39.1 <C_T < 40.0 indicates the presence of a low load of the organism and needs further determination of either colonization or probable/possible Pneumocystis pneumonia. Overall, the new assay demonstrates excellent analytical and clinical performance and may be more sensitive than mtLSU PCR target for the detection of P. jirovecii.

Clinical Performance of (1,3) Beta-D Glucan for the Diagnosis of Pneumocystis Pneumonia (PCP) in Cancer Patients Tested With PCP Polymerase Chain Reaction

BACKGROUND

Serum (1,3)-beta-D glucan (BDG) is increasingly used to guide the management of suspected Pneumocystis pneumonia (PCP). BDG lacks specificity for PCP, and its clinical performance in high-risk cancer patients has not been fully assessed. Polymerase chain reaction (PCR) for PCP detection is highly sensitive, but cannot differentiate between colonization and infection. We evaluated the diagnostic performance of serum BDG in conjunction with PCP PCR on respiratory samples in patients with cancer and unexplained lung infiltrates.

METHODS

We performed a retrospective analysis of adult patients evaluated for PCP at our institution from 2012 to 2015, using serum BDG and PCP PCR. The sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of the serum BDG at different thresholds were evaluated using PCP PCR alone or in conjunction with clinical presentation in PCP PCR-positive patients.

RESULTS

With PCP PCR alone as the reference method, BDG (≥80 pg/mL) had a sensitivity of 69.8%, specificity of 81.2%, PPV of 34.6%, and NPV of 95.2% for PCP. At ≥200 pg/mL in patients with a positive PCR and a compatible PCP clinical syndrome, BDG had a sensitivity of 70%, specificity of 100%, PPV of 100%, and NPV of 52.0% for PCP.

CONCLUSIONS

Patients negative by both BDG and PCR were unlikely to have PCP. In patients with a compatible clinical syndrome for PCP, higher BDG values (>200 pg/mL) were consistently associated with clinically-significant PCP infections among PCP PCR-positive oncology patients.

(1→3)-β-D-glucan testing for the detection of invasive fungal infections in immunocompromised or critically ill people

BACKGROUND

Invasive fungal infections (IFIs) are life-threatening opportunistic infections that occur in immunocompromised or critically ill people. Early detection and treatment of IFIs is essential to reduce morbidity and mortality in these populations. (1→3)-β-D-glucan (BDG) is a component of the fungal cell wall that can be detected in the serum of infected individuals. The serum BDG test is a way to quickly detect these infections and initiate treatment before they become life-threatening. Five different versions of the BDG test are commercially available: Fungitell, Glucatell, Wako, Fungitec-G, and Dynamiker Fungus.

OBJECTIVES

To compare the diagnostic accuracy of commercially available tests for serum BDG to detect selected invasive fungal infections (IFIs) among immunocompromised or critically ill people.

SEARCH METHODS

We searched MEDLINE (via Ovid) and Embase (via Ovid) up to 26 June 2019. We used SCOPUS to perform a forward and backward citation search of relevant articles. We placed no restriction on language or study design.

SELECTION CRITERIA

We included all references published on or after 1995, which is when the first commercial BDG assays became available. We considered published, peer-reviewed studies on the diagnostic test accuracy of BDG for diagnosis of fungal infections in immunocompromised people or people in intensive care that used the European Organization for Research and Treatment of Cancer (EORTC) criteria or equivalent as a reference standard. We considered all study designs (case-control, prospective consecutive cohort, and retrospective cohort studies). We excluded case studies and studies with fewer than ten participants. We also excluded animal and laboratory studies. We excluded meeting abstracts because they provided insufficient information.

DATA COLLECTION AND ANALYSIS

We followed the standard procedures outlined in the Cochrane Handbook for Diagnostic Test Accuracy Reviews. Two review authors independently screened studies, extracted data, and performed a quality assessment for each study. For each study, we created a 2 × 2 matrix and calculated sensitivity and specificity, as well as a 95% confidence interval (CI). We evaluated the quality of included studies using the Quality Assessment of Studies of Diagnostic Accuracy-Revised (QUADAS-2). We were unable to perform a meta-analysis due to considerable variation between studies, with the exception of Candida, so we have provided descriptive statistics such as receiver operating characteristics (ROCs) and forest plots by test brand to show variation in study results.

MAIN RESULTS

We included in the review 49 studies with a total of 6244 participants. About half of these studies (24/49; 49%) were conducted with people who had cancer or hematologic malignancies. Most studies (36/49; 73%) focused on the Fungitell BDG test. This was followed by Glucatell (5 studies; 10%), Wako (3 studies; 6%), Fungitec-G (3 studies; 6%), and Dynamiker (2 studies; 4%). About three-quarters of studies (79%) utilized either a prospective or a retrospective consecutive study design; the remainder used a case-control design. Based on the manufacturer's recommended cut-off levels for the Fungitell test, sensitivity ranged from 27% to 100%, and specificity from 0% to 100%. For the Glucatell assay, sensitivity ranged from 50% to 92%, and specificity ranged from 41% to 94%. Limited studies have used the Dynamiker, Wako, and Fungitec-G assays, but individual sensitivities and specificities ranged from 50% to 88%, and from 60% to 100%, respectively. Results show considerable differences between studies, even by manufacturer, which prevented a formal meta-analysis. Most studies (32/49; 65%) had no reported high risk of bias in any of the QUADAS-2 domains. The QUADAS-2 domains that had higher risk of bias included participant selection and flow and timing.

AUTHORS' CONCLUSIONS

We noted considerable heterogeneity between studies, and these differences precluded a formal meta-analysis. Because of wide variation in the results, it is not possible to estimate the diagnostic accuracy of the BDG test in specific settings. Future studies estimating the accuracy of BDG tests should be linked to the way the test is used in clinical practice and should clearly describe the sampling protocol and the relationship of time of testing to time of diagnosis.

Ability of quantitative PCR to discriminate Pneumocystis jirovecii pneumonia from colonization

Introduction.

Pneumocystis jirovecii pneumonia (PCP) is a severe disease affecting immunocompromised patients. Diagnosis is difficult due to the low sensitivity of direct examination and inability to grow the pathogen in culture. Quantitative PCR in bronchoalveolar lavage fluid (BAL) has high sensitivity, but limited specificity for distinguishing PCP from colonization.

Aim.

To assess the performance of an in-house quantitative PCR to discriminate between PCP and colonization.

Methodology.

This was a single-centre retrospective study including all patients with a positive PCR result for P. jirovecii in BAL between 2009 and 2017. Irrespective of PCR results, PCP was defined as the presence of host factors and clinical/radiological criteria consistent with PCP and (i) the presence of asci at direct examination of respiratory sample or (ii) anti-PCP treatment initiated with clinical response and absence of alternative diagnosis. Colonization was considered for cases who did not receive anti-PCP therapy with a favourable outcome or an alternative diagnosis. Cases who did not meet the above mentioned criteria were classified as ‘undetermined’.

Results.

Seventy-one patients with positive P. jirovecii PCR were included (90 % non-HIV patients). Cases were classified as follows: 37 PCP, 22 colonization and 12 undetermined. Quantitative PCR values in BAL were significantly higher in patients with PCP versus colonization or undetermined (P<0.0001). The cut-off of 5×10³ copies/ml was able to discriminate PCP cases from colonization with 97 % sensitivity, 82 % specificity, 90 % positive predictive value and 95 % negative predictive value.

Conclusions.

Our quantitative PCR for P. jirovecii in BAL was reliable to distinguish PCP cases from colonization in this predominantly non-HIV population.

Evaluation of the performance of DiaSorin molecular Pneumocystis jirovecii-CMV multiplex real-time PCR assay from bronchoalveolar lavage samples

The aim of this study was to evaluate the performance of the DiaSorin Molecular PJ-CMV multiplex real-time PCR (PJ-CMV PCR) assay (DiaSorin Molecular LLC, USA) in bronchoalveolar lavage (BAL) samples compared to direct immunofluorescence assay (IFA) for the detection of Pneumocystis jirovecii and assess CMV and P. jirovecii co-infection rate in immunosuppressed patients with suspected pneumonia. A total of 125 BAL samples from immunosuppressed patients submitted for PJP-IFA were tested. Surplus samples were saved and further tested by using the PJ-CMV PCR assay. Among the 125 samples, P. jirovecii was detected in 31.2% (39/125) and in 40% (50/125) of the specimens using IFA and PJ-CMV PCR respectively. Eleven of the PJ-CMV PCR positive samples were negative by direct IFA for P. jirovecii. All samples positive by direct IFA were also positive by PJ-CMV PCR. Using the direct IFA as a gold standard, the PJ-CMV PCR sensitivity, specificity, positive predictive value and negative predictive value for detection of P. jirovecii were 100%, 87.2%, 78% and 100%, respectively. However, after reviewing the clinical diagnosis, the specificity and PPV increased to 100%. Of the 50 P. jirovecii samples positive by PJ-CMV PCR, 18 (36%) were also positive for CMV by the PJ-CMV PCR. The co-infection rate was found to be 37.5% (6/16) and 35.2% (12/34) in HIV infected and non-HIV infected patients. This study indicated that the DiaSorin Molecular PJ-CMV multiplex real-time PCR assay has higher sensitivity than direct IFA for detection of P. jirovecii and provides rapid detection of PJ and CMV infection in BAL samples.

A New Age in Molecular Diagnostics for Invasive Fungal Disease: Are We Ready?

Invasive fungal diseases (IFDs) present an increasing global burden in immunocompromised and other seriously ill populations, including those caused by pathogens which are inherently resistant or less susceptible to antifungal drugs. Early diagnosis encompassing accurate detection and identification of the causative agent and of antifungal resistance is critical for optimum patient outcomes. Many molecular-based diagnostic approaches have good clinical utility although interpretation of results should be according to clinical context. Where an IFD is in the differential diagnosis, panfungal PCR assays allow the rapid detection/identification of fungal species directly from clinical specimens with good specificity; sensitivity is also high when hyphae are seen in the specimen including in paraffin-embedded tissue. Aspergillus PCR assays on blood fractions have good utility in the screening of high risk hematology patients with high negative predictive value (NPV) and positive predictive value (PPV) of 94 and 70%, respectively, when two positive PCR results are obtained. The standardization, and commercialization of Aspergillus PCR assays has now enabled direct comparison of results between laboratories with commercial assays also offering the simultaneous detection of common azole resistance mutations. Candida PCR assays are not as well standardized with the only FDA-approved commercial system (T2Candida) detecting only the five most common species; while the T2Candida outperforms blood culture in patients with candidemia, its role in routine Candida diagnostics is not well defined. There is growing use of Mucorales-specific PCR assays to detect selected genera in blood fractions. Quantitative real-time Pneumocystis jirovecii PCRs have replaced microscopy and immunofluorescent stains in many diagnostic laboratories although distinguishing infection may be problematic in non-HIV-infected patients. For species identification of isolates, DNA barcoding with dual loci (ITS and TEF1α) offer optimal accuracy while next generation sequencing (NGS) technologies offer highly discriminatory analysis of genetic diversity including for outbreak investigation and for drug resistance characterization. Advances in molecular technologies will further enhance routine fungal diagnostics.

Gomori Methenamine Silver Stain on Bronchoalveolar Lavage Fluid Is Poorly Sensitive for Diagnosis of Pneumocystis jiroveci Pneumonia in HIV-Negative Immunocompromised Patients and May Lead to Missed or Delayed Diagnoses

CONTEXT.—

Direct visualization of Pneumocystis jiroveci organisms, using Gomori methenamine silver (GMS) staining in bronchoalveolar lavage fluid (BAL), is a historical gold standard that has been widely used for the diagnosis of P jiroveci pneumonia (PJP). However, the stain may be less sensitive in human immunodeficiency virus (HIV)-negative immunocompromised patients owing to a lower burden of organisms.

OBJECTIVES.—

To assess the sensitivity of the GMS stain on BAL fluid for the diagnosis of PJP in HIV-negative immunocompromised patients as compared to HIV-positive patients.

DESIGN.—

We conducted a retrospective review from 2012 to 2018 to identify immunocompromised patients (≥18 years old) who underwent bronchoscopy with BAL GMS staining for the diagnosis of PJP. To assess for sensitivity, we sought to identify BAL GMS-positive cases and BAL GMS-negative cases of PJP. The BAL GMS-negative cases were categorized into proven and probable PJP.

RESULTS.—

We identified 45 adult immunocompromised patients with proven and probable PJP, including 24 HIV-negative (11 BAL GMS-positive and 13 BAL GMS-negative) and 21 HIV-positive cases (all were BAL GMS-positive). The sensitivity of BAL GMS for the diagnosis of PJP in HIV-negative immunocompromised patients was 11 of 24 (46%) versus 21 of 21 (100%) in HIV-positive patients (CD4: median, 10 cells/mL; range, 3-300 cells/mL). Delayed or missed diagnoses were seen in 3 cases of BAL GMS-negative PJP. Re-examination of BAL GMS slides showed rare P jiroveci cysts in 1 case.

CONCLUSIONS.—

BAL GMS has poor sensitivity for PJP in HIV-negative immunocompromised patients. Using BAL GMS as a sole method for PJP may result in missed or delayed diagnoses in this population.

Quantification of Pneumocystis jirovecii: Cross-Platform Comparison of One qPCR Assay with Leading Platforms and Six Master Mixes

Diagnosis of Pneumocystis jirovecii pneumonia relies on nucleic acid quantification in respiratory samples. Lack of standardization among molecular assays results in significant differences among assays/centers. To further promote standardization, we compared four thermocyclers and six master mixes for the detection of P. jirovecii. Whole nucleic acid (WNA) was extracted from broncho-alveolar lavages. Positive and negative sample extracts were pooled to get enough homogeneous materials. Three master mixes were tested to detect DNA by qPCR (D1, D2, and D3), and three to detect WNA by reverse transcriptase qPCR (W1, W2, and W3) manufactured by Roche, Eurogentec, Applied Biosystem, Invitrogen and Thermofischer Scientific. Experiments were performed on four thermocyclers (Roche LightCycler 480, Qiagen Rotor-Gene Q, Applied Biosystem ABI7500, and QuantStudio). Comparison of quantitative cycle (Cq) values between the methods targeting WNA versus DNA showed lower Cq values for WNA, independently of thermocycler and master mix. For high and low fungal loads, ∆Cq values between DNA and WNA amplification were 6.97 (±2.95) and 5.81 (±3.30), respectively (p < 0.0001). Regarding DNA detection, lower Cqs were obtained with D1 compared to D2 and D3, with median ∆Cq values of 2.6 (p = 0.015) and 2.9 (p = 0.039) respectively. Regarding WNA detection, no mix was superior to the others. PCR efficiency was not significantly different according to the qPCR platform (p = 0.14). This study confirmed the superiority of WNA over DNA detection. A calibration method (e.g., an international standard) for accurate comparative assessment of fungal load seems necessary.

Pneumocystis jiroveci in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of Pneumocystis jiroveci fungal infection transplant recipients. Pneumonia (PJP) may develop via airborne transmission or reactivation of prior infection. Nosocomial clusters of infection have been described among transplant recipients. PJP should not occur during prophylaxis with trimethoprim-sulfamethoxazole (TMP-SMX). Without prophylaxis, PJP risk is greatest in the first 6 months after organ transplantation but may develop later. Risk factors include low lymphocyte counts, cytomegalovirus infection (CMV), hypogammaglobulinemia, treated graft rejection or corticosteroids, and advancing patient age (>65). Presentation typically includes fever, dyspnea with hypoxemia, and cough. Chest radiographic patterns generally reveal diffuse interstitial processes best seen by CT scans. Patients generally have PO₂  < 60 mm Hg, elevated serum lactic dehydrogenase (LDH), and elevated serum (1 → 3) β-d-glucan assay. Specific diagnosis uses respiratory specimens with direct immunofluorescent staining; invasive procedures may be required. Quantitative PCR is a useful adjunct to diagnosis. TMP-SMX is the drug of choice for therapy; drug allergy should be documented before resorting to alternative therapies. Adjunctive corticosteroids may be useful early. Routine PJP prophylaxis is recommended for at least 6-12 months post-transplant, preferably with TMP-SMX.

Treating bacterial pneumonia in people living with HIV

Introduction: Bacterial pneumonia remains an important cause of morbidity and mortality in people living with HIV (PLWH) in the antiretroviral therapy (ART) era. In addition to being immunocompromised, as reflected by low CD4 cell counts and elevated HIV viral loads, PLWH often have other behaviors associated with an increased risk of pneumonia including smoking and injected drug use. As PLWH are aging, comorbid conditions such as chronic obstructive pulmonary disease (COPD), cancers, and cardiovascular, renal and liver diseases are emerging as additional risk factors for pneumonia. Pathogens are often similar to those in HIV-uninfected individuals; however, PLWH are at risk for unusual and/or multi-drug resistant organisms causing bacterial pneumonia based, in part, on their CD4 cell counts and other exposures. Areas covered: In this review, we focus on the recognition and management of bacterial community-acquired pneumonia (CAP) in PLWH. Along with antimicrobial treatment, we discuss prevention strategies such as vaccination and smoking cessation. Expert opinion: Early initiation of ART after HIV infection can decrease the risk of pneumonia. Improved efforts at vaccination, smoking cessation, and reduction of other substance use are urgently needed in PLWH to decrease the risk for bacterial pneumonia. As PLWH are aging, comorbidities are additional risk factors for bacterial CAP.

Beta-d-Glucan for Diagnosing Pneumocystis Pneumonia: a Direct Comparison between the Wako β-Glucan Assay and the Fungitell Assay

Measuring serum beta-d-glucan (BDG) is a useful tool for supporting a quantitative PCR (qPCR)-based diagnosis of suspected Pneumocystis pneumonia (PCP) with bronchoalveolar lavage (BAL) fluid. Since the 2000s, the Fungitell assay was the only BDG assay which was FDA cleared and Conformité Européenne (CE) marked. However, the Wako β-glucan test was also recently CE marked and commercialized. We analyzed archived sera from 116 PCP cases (who were considered to have PCP based on compatible clinical and radiological findings plus a BAL fluid qPCR threshold cycle value of ≤28) and 114 controls (those with a BAL fluid qPCR threshold cycle value of >45 and no invasive fungal infection) using the Fungitell and Wako assays in parallel and assessed their diagnostic performance using the manufacturer's proposed cutoffs of 80 pg/ml and 11 pg/ml, respectively. We found the Wako assay to be more specific (0.98 versus 0.87, P < 0.001) and the Fungitell assay to be more sensitive (0.78 versus 0.85, P = 0.039) at the proposed cutoffs. Overall performance, as determined by the area under the receiver operating characteristic curve, was similar for both assays. We determined a new Wako assay cutoff (3.616 pg/ml) to match the sensitivity of the Fungitell assay (0.88 at a cutoff of ≥60 pg/ml). Using this newly proposed cutoff, the specificity of the Wako assay was significantly better than that of the Fungitell assay (0.89 versus 0.82, P = 0.011). In conclusion, the Wako assay performed excellently compared to the Fungitell assay for the diagnosis of presumed PCP based on qPCR. In addition, contrary to the Fungitell assay, the Wako assay allows for single-sample testing with lower inter- and intrarun variability. Finally, we propose an optimized cutoff for the Wako assay to reliably exclude PCP.

Comparative Evaluation Between the RealStar Pneumocystis jirovecii PCR Kit and the AmpliSens Pneumocystis jirovecii (carinii)-FRT PCR Kit for Detecting P. jirovecii in Non-HIV Immunocompromised Patients

BACKGROUND

Real-time PCR is more sensitive than microscopic examination for detecting Pneumocystis jirovecii. We compared the performance of two assays for detecting P. jirovecii DNA: the RealStar Pneumocystis jirovecii PCR Kit 1.0 CE (Altona Diagnostics, Hamburg, Germany) and the AmpliSens Pneumocystis jirovecii (carinii)-FRT PCR kit (InterLabService Ltd., Moscow, Russia).

METHODS

We used 159 samples from the lower respiratory tract (112 bronchoalveolar lavage [BAL] fluid, 37 sputum, and 10 endotracheal aspirate [ETA] samples) of non-HIV immunocompromised patients. Nested PCR and sequencing were used to resolve discordant results. The performance of the two assays was evaluated according to clinical categories (clinical Pneumocystis pneumonia [PCP], possible PCP, or unlikely PCP) based on clinical and radiological observations.

RESULTS

The positive and negative percent agreement values were 100% (95% confidence interval [CI], 85.4-100%) and 96.6% (95% CI, 90.9-98.9%), respectively, and kappa was 0.92 (95% CI, 0.84-0.99). P. jirovecii DNA load was significantly higher in the clinical PCP group than in the other groups (P<0.05). When stratified by sample type, the positive rate for BAL fluids from the clinical PCP group was 100% using either assay, whereas the positive rate for sputum/ETA samples was only 20%.

CONCLUSIONS

The two assays showed similar diagnostic performance and detected low P. jirovecii burden in BAL fluids. Both assays may be useful as routine methods for detecting P. jirovecii DNA in a clinical laboratory setting, though their results should be interpreted considering sample type.

Risk factors and clinical characteristics of Pneumocystis jirovecii pneumonia in lung cancer

Solid malignancies are associated with the development of Pneumocystis jirovecii pneumonia (PJP). This study aimed to evaluate the risk factors for PJP among patients with lung cancer. This retrospective case-control study compared patients who had lung cancer with PJP (n = 112) or without PJP (n = 336) matched according to age, sex, histopathology, and stage. PJP definition was based on (i) positive PCR or direct immunofluorescence results for pneumocystis, (ii) clinical symptoms and radiological abnormalities that were consistent with a pneumonic process, and (iii) received targeted PJP treatment. The development of PJP was associated with radiotherapy (RTx), concurrent chemoradiotherapy (CCRTx), lymphopenia, and prolonged high-dose steroid therapy (20 mg of prednisolone equivalent per day for ≥3 weeks). Multivariate analysis revealed independent associations with prolonged high-dose steroid therapy (odds ratio [OR]: 1.96, 95% confidence interval [CI]: 1.06-3.63; p = 0.032) and CCRTx (OR: 2.09, 95% CI: 1.27-3.43; p = 0.004). Steroid use was frequently related to RTx pneumonitis or esophagitis (29 patients, 43.3%). Prolonged high-dose steroid therapy and CCRTx were risk factors for PJP development among patients with lung cancer. As these patients had a poor prognosis, clinicians should consider PJP prophylaxis for high-risk patients with lung cancer.

Development of a fully automated PCR assay for the detection of Pneumocystis jirovecii using the GENECUBE system

We developed a fully automated polymerase chain reaction (PCR) assay for the detection of Pneumocystis jirovecii using the GENECUBE system. This assay was evaluated against an in-house real-time PCR assay using 82 bronchoalveolar lavage and 139 sputum samples from 221 immunocompromised patients who were suspected of having Pneumocystis pneumonia (PCP). After loading the maximum of eight samples into the GENECUBE system, the results were obtained within approximately 60 minutes. The overall positivity rate of both assays was 35%, and the concordance rate was 89% (kappa, 0.76). Based on the clinical diagnosis of 39 PCP and 105 non-PCP patients, the GENECUBE and real-time assays had sensitivities of 92.3% and 94.9% and specificities of 85.7% and 85.7%, respectively. This automated and rapid assay is a promising tool for the detection of P. jirovecii in routine clinical laboratory practice.

Therapy and Management of Pneumocystis jirovecii Infection

The rates of Pneumocystis pneumonia (PcP) are increasing in the HIV-negative susceptible population. Guidance for the prophylaxis and treatment of PcP in HIV, haematology, and solid-organ transplant (SOT) recipients is available, although for many other populations (e.g., auto-immune disorders) there remains an urgent need for recommendations. The main drug for both prophylaxis and treatment of PcP is trimethoprim/sulfamethoxazole, but resistance to this therapy is emerging, placing further emphasis on the need to make a mycological diagnosis using molecular based methods. Outbreaks in SOT recipients, particularly renal transplants, are increasingly described, and likely caused by human-to-human spread, highlighting the need for efficient infection control policies and sensitive diagnostic assays. Widespread prophylaxis is the best measure to gain control of outbreak situations. This review will summarize diagnostic options, cover prophylactic and therapeutic management in the main at risk populations, while also covering aspects of managing resistant disease, outbreak situations, and paediatric PcP.

Role of Pneumocystis jirovecii in patients with different pulmonary underlying condition using a nested-PCR

OBJECTIVE

The prevalence of Pneumocystis jirovecii colonization and its role in pulmonary disease remains unclear. PCR methods have shown an improved sensitivity in the detection of this fungus. It has been suggested that the PCR results be combined with another test such as IFA to create a diagnostic algorithm.

METHODS

A multiplex nested-PCR procedure with a 16S rRNA gene as the internal amplification control was evaluated to determine the role of P. jirovecii in pulmonary disease.

RESULTS

A 20% of the 199 bronchoalveolar lavage samples were PCR-positive, 13.5% samples were PCR-inhibited, and the rate of Pneumocystis-colonisation was 6.4%. The sensitivity, specificity, positive predictive value and negative predictive value of the nested-PCR were 100%, 93%, 70% and 100%, respectively. The sensitivity of the nested-PCR was higher than the current "gold standard" immunofluorescence assay (IFA) (p< 0.0001). PCR-negative and PCR-positive patients did not show any clinical or radiological differences in the medical variables studied.

CONCLUSIONS

PCR could help the diagnosis of Pneumocystis pulmonary disease given the high negative predictive value of the technique. P. jirovecii DNA can frequently be detected in healthy population, so the analysis of the patient medical history is critical to make the correct clinical decision.

Clinical, Diagnostic, and Treatment Disparities between HIV-Infected and Non-HIV-Infected Immunocompromised Patients with Pneumocystis jirovecii Pneumonia

The substantial decline in the Pneumocystis jirovecii pneumonia (PCP) incidence in HIV-infected patients after the introduction of antiretroviral therapy (ART) in resource-rich settings and the growing number of non-HIV-infected immunocompromised patients at risk leads to considerable epidemiologic changes with clinical, diagnostic, and treatment consequences for physicians. HIV-infected patients usually develop a subacute course of disease, while non-HIV-infected immunocompromised patients are characterized by a rapid disease progression with higher risk of respiratory failure and higher mortality. The main symptoms usually include exertional dyspnea, dry cough, and subfebrile temperature or fever. Lactate dehydrogenase may be elevated. Typical findings on computed tomography scans of the chest are bilateral ground-glass opacities with or without cystic lesions, which are usually associated with the presence of AIDS. Empiric treatment should be initiated as soon as PCP is suspected. Bronchoalveolar lavage has a higher diagnostic yield compared to induced sputum. Immunofluorescence is superior to conventional staining. A combination of different diagnostic tests such as microscopy, polymerase chain reaction, and (1,3)-β-D-glucan is recommended. Trimeth-oprim/sulfamethoxazole for 21 days is the treatment of choice in adults and children. Alternative treatment regimens include dapsone with trimethoprim, clindamycin with primaquine, atovaquone, or pentamidine. Patients with moderate to severe disease should receive adjunctive corticosteroids. In newly diagnosed HIV-infected patients with PCP, ART should be initiated as soon as possible. In non-HIV-infected immunocompromised patients, improvement of the immune status should be discussed (e.g., temporary reduction of immunosuppressive agents). PCP prophylaxis is effective and depends on the immune status of the patient and the underlying immunocompromising disease.

Infectious complications after hematopoietic stem cell transplantation: current status and future perspectives in Korea

Hematopoietic stem cell transplantation (HSCT) is a treatment for hematologic malignancies, immune deficiencies, or genetic diseases, ect. Recently, the number of HSCTs performed in Korea has increased and the outcomes have improved. However, infectious complications account for most of the morbidity and mortality after HSCT. Post-HSCT infectious complications are usually classified according to the time after HSCT: pre-engraftment, immediate post-engraftment, and late post-engraftment period. In addition, the types and risk factors of infectious complications differ according to the stem cell source, donor type, conditioning intensity, region, prophylaxis strategy, and comorbidities, such as graft-versushost disease and invasive fungal infection. In this review, we summarize infectious complications after HSCT, focusing on the Korean perspectives.