Human metapneumovirus as cause of severe community-acquired pneumonia in adults: insights from a ten-year molecular and epidemiological analysis

Lobar pneumonia due to human metapneumovirus: a case report

Human metapneumovirus (hMPV) is a respiratory pathogen that can cause lower respiratory tract infections and pneumonia in immunocompetent adults. Pneumonia caused by hMPV is reportedly more likely to cause bronchial wall thickening and ground-glass opacity (GGO). A 44-year-old woman with no significant medical history developed fever, cough, and nausea. Computed tomography of the chest showed scattered GGOs in the right upper lobe and infiltrating shadows with air bronchograms in the left lingual and bilateral lower lobes. The patient was admitted to our hospital for further evaluation. Atypical pneumonia was suspected and lascufloxacin (LSFX) was started. Multiplex polymerase chain reaction (PCR) detected hMPV on hospital day 2 using the FilmArray Respiratory Panel 2.1. Pneumonia due to hMPV was suspected and LSFX was discontinued. The patient subsequently showed spontaneous improvement and was discharged on hospital day 6 after admission. After discharge, pneumonia continued to improve. Early detection of respiratory pathogens using multiplex PCR can help determine the appropriate treatment strategy. As hMPV can also cause lobar pneumonia, we should consider pneumonia due to hMPV in the differential diagnosis of lobar pneumonia.

Human monoclonal antibodies protect against viral-mediated pneumococcal superinfection

Introduction

Community-acquired pneumonia (CAP) is a global health concern, with 25% of cases attributed to Streptococcus pneumoniae (Spn). Viral infections like influenza A virus (IAV), respiratory syncytial virus (RSV), and human metapneumovirus (hMPV) increase the risk of Spn, leading to severe complications due to compromised host immunity.

Methods

We evaluated the efficacy of an anti-PhtD monoclonal antibody (mAb) cocktail therapy (PhtD3 + 7) in improving survival rates in three viral/bacterial coinfection models: IAV/Spn, hMPV/Spn, and RSV/Spn.

Results

The PhtD3 + 7 mAb cocktail outperformed antiviral mAbs, resulting in prolonged survival. In the IAV/Spn model, it reduced bacterial titers in blood and lungs by 2-4 logs. In the hMPV/Spn model, PhtD3 + 7 provided greater protection than the hMPV-neutralizing mAb MPV467, significantly reducing bacterial titers. In the RSV/Spn model, PhtD3 + 7 offered slightly better protection than the antiviral mAb D25, uniquely decreasing bacterial titers in blood and lungs.

Discussion

Given the threat of antibiotic resistance, our findings highlight the potential of anti-PhtD mAb therapy as an effective option for treating viral and secondary pneumococcal coinfections.

Determinants of radiological patterns and severity in immunocompromised adults with Metapneumovirus infection

BACKGROUND

Human Metapneumovirus (HMPV) belongs to the Pneumoviridae family and is responsible for respiratory infections. Mild infections are well-recognized in children, while its precise impact in various categories of immunocompromised adults has not been well addressed.

RESEARCH QUESTION

We retrospectively studied HMPV infections in immunocompromised adults followed in two large French university medical centers.

STUDY DESIGN AND METHODS

We identified immunocompromised adults with positive HMPV Polymerase Chain Reaction (PCR) for 36 months and reviewed their medical charts. For lung transplant recipients (LTR), FEV1 was collected at baseline, during and after infection. Imaging was centralized and chest involvement was categorized by dominant CT patterns. We compared severe patients (requiring oxygen or ventilation) and non hypoxemic patients.

RESULTS

Seventy-two patients were included, 27 were LTR, 25 had a hematological malignancy or were hematopoietic stem cell recipients, 20 had another immunocompromised status. Twenty patients (28%) presented a hypoxemic infection, requiring hospitalization and intensive care units transfers in 50/72 (69.4%) and 9/72 (12.5%) respectively, with only one death. Hypoxemia was less pronounced in LTRs (p = 0.014). Finally, age and dyspnea remained independent factors associated with hypoxemia (p < 0.005). The most frequent radiological patterns were bronchopneumonia (34.2%) and bronchiolitis (39.5% and 64.3% in the overall population and in LTRs respectively, p = 0.045). FEV1 improved in LTRs at one month and 85% had recovered their baseline FEV1 within 6 months.

INTERPRETATIONS

In immunocompromised adults, HMPV infections required frequent hospitalizations and ICU transfers, while mortality is low. In LTRs, bronchiolitis pattern was predominant with short and long-term favorable outcome.

The relationship between lactate dehydrogenase and Apolipoprotein A1 levels in patients with severe pneumonia

Background

To investigate the relationship between lactate dehydrogenase and apolipoprotein A1 levels and the condition and prognosis of patients with severe pneumonia.

Methods

Data was collected from 204 patients with severe pneumonia who were hospitalized from January 1, 2019 to December 1, 2021 in Zhaotong First People's Hospital (respiratory intensive care unit (RICU)), and divided into survival group (160 patients) and death group (44 patients) according to their hospitalization outcome. The relationship between lactate dehydrogenase and apolipoprotein A1 levels and general information, disease, and treatment needs of patients with severe pneumonia was analyzed, and lactate dehydrogenase, apolipoprotein A1, neutrophil-to-lymphocyte ratio, hematocrit, C-reactive protein, calcitoninogen, D-dimer, Acute Physiology and Chronic Health Status Rating System II, and Pneumonia Severity Index scores were compared between the survival and death groups. The value of these indicators in determining the prognosis of patients was analyzed using subject operating characteristic (ROC) curves. Logistic regression was used to analyze the risk factors for death from severe pneumonia.

Viral Pneumonia: From Influenza to COVID-19

Respiratory viruses are increasingly recognized as a cause of community-acquired pneumonia (CAP). The implementation of new diagnostic technologies has facilitated their identification, especially in vulnerable population such as immunocompromised and elderly patients and those with severe cases of pneumonia. In terms of severity and outcomes, viral pneumonia caused by influenza viruses appears similar to that caused by non-influenza viruses. Although several respiratory viruses may cause CAP, antiviral therapy is available only in cases of CAP caused by influenza virus or respiratory syncytial virus. Currently, evidence-based supportive care is key to managing severe viral pneumonia. We discuss the evidence surrounding epidemiology, diagnosis, management, treatment, and prevention of viral pneumonia.

Severe community-acquired pneumonia in the post COVID-19 era

PURPOSE OF REVIEW

The aim was to examine and summarize the most recent published literature in the last years stating the advances for treatment options and adjunctive therapies in patients hospitalized with severe community-acquired pneumonia (sCAP). Search was performed in PubMed, including observational studies, randomized controlled trials, systematic reviews and meta-analyses, and international guidelines.

RECENT FINDINGS

Regardless of a large number of published CAP guidelines, most of their recommendations are based on low-level evidence.Viruses have an increasing role as sCAP etiology with an impact on mortality. Accordingly, it is imperative to strengthen the demand for vaccines and newer antivirals. Considering an early monitoring of the immune response in patients with severe Influenza, may help to evaluate a personalized immunomodulatory strategy. Despite growing evidence, the use of corticosteroids as an adjunctive therapy in bacterial sCAP continues to be controversial.

SUMMARY

Mortality due to sCAP still remains undesirably high. This fact strengthens the need for more high-quality research to increase evidence. It also highlights the need for clinicians to be aware of the level of evidence of the stated recommendations, taking this into consideration before decision making.

Clinical significance of human metapneumovirus detection in critically ill adults with lower respiratory tract infections

BACKGROUND

Unlike other viruses, the pathogenicity of human metapneumovirus (hMPV) in adults remains uncertain. To address this question, a retrospective monocentric cohort including all patients admitted to ICU with hMPV infection between January 1, 2010, and June 30, 2018 was performed. The characteristics of hMPV infected patients were studied and compared to matched influenza infected patients. Consecutively, a systematic review and meta-analyses investigating PUBMED, EMBASE and COCHRANE databases was conducted to explore the hMPV infections in adult patients (PROSPERO number: CRD42018106617). Trials, case series, and cohorts published between January 1, 2008 and August 31, 2019 compiling adults presenting hMPV infections were included. Pediatric studies were excluded. Data were extracted from published reports. Primary endpoint was the rate of low respiratory tract infections (LRTIs) among all hMPV infected patients.

RESULTS

During the study period, 402 patients were tested positive for hMPV. Among them 26 (6.5%) patients were admitted to the ICU, 19 (4.7%) for acute respiratory failure. Twenty-four (92%) were immunocompromised. Bacterial coinfections were frequent 53.8%. Hospital mortality rate was 30.8%. In the case-control analysis, the clinical and imaging characteristics were not different between hMPV and influenza infected patients. The systematic review identified 156 studies and 69 of them (1849 patients) were eligible for analysis. Although there was heterogeneity between the studies, the rate of hMPV LRTIs was 45% (95% CI 31-60%; I² = 98%). Intensive care unit (ICU) admission was required for 33% (95% CI 21-45%; I² = 99%). Hospital mortality rate was 10% (95% CI 7-13%; I² = 83%) and ICU mortality rate was 23% (95% CI 12-34%; I² = 65%). Underlying malignancy was independently associated with increased mortality rate.

CONCLUSIONS

This preliminary work suggested that hMPV may be associated with severe infection and high mortality in patients with underlying malignancies. However, regarding the small size of the cohort and the heterogeneity of the review, more cohort studies are warranted.

Respiratory illness virus infections with special emphasis on COVID-19

Viruses that emerge pose challenges for treatment options as their uniqueness would not know completely. Hence, many viruses are causing high morbidity and mortality for a long time. Despite large diversity, viruses share common characteristics for infection. At least 12 different respiratory-borne viruses are reported belonging to various virus taxonomic families. Many of these viruses multiply and cause damage to the upper and lower respiratory tracts. The description of these viruses in comparison with each other concerning their epidemiology, molecular characteristics, disease manifestations, diagnosis and treatment is lacking. Such information helps diagnose, differentiate, and formulate the control measures faster. The leading cause of acute illness worldwide is acute respiratory infections (ARIs) and are responsible for nearly 4 million deaths every year, mostly in young children and infants. Lower respiratory tract infections are the fourth most common cause of death globally, after non-infectious chronic conditions. This review aims to present the characteristics of different viruses causing respiratory infections, highlighting the uniqueness of SARS-CoV-2. We expect this review to help understand the similarities and differences among the closely related viruses causing respiratory infections and formulate specific preventive or control measures.

Epidemiology of respiratory virus before and during COVID-19 pandemic

The COVID pandemic has forcefully turned the spotlight on the importance of the diagnosis of respiratory virus infections. Viruses have always been a frequent and common cause of respiratory tract infections. Rapid molecular diagnostics applied to the diagnostics of respiratory virus infections has revolutionized microbiology laboratories only a few years ago. Few studies illustrate the epidemiology of respiratory viruses, and fewer still those that have compared the pre-pandemic to the pandemic period. During the first year of the pandemic (2020-2021) it was clear to everyone to witness a sudden disappearance of the circulation of all the other respiratory viruses, especially those typically isolated during the winter time, such as RSV and Influenza virus. In our study we wanted to verify this phenomenon and to study the epidemiology of our local reality, analyzing three consecutive flu seasons (2018-2019, 2019-2020, 2020-2021). The results lead us to note that the prevalence of positivity to respiratory virus infections went from 49.8% (2018-2019) and 39% (2019-2020) to 13.4% (2020-2021). This decrease is at least partly attributable to the security measures adopted (social distancing and mask), but it certainly opens up new scenarios when the restriction measures will be terminated. We believe such studies can provide real-world evidence of the effectiveness of public health interventions implemented during current and future pandemics.

Respiratory viral infections in pragmatically selected adults in intensive care units

Respiratory viruses can be detected in 18.3 to 48.9% of critically ill adults with severe respiratory tract infections (RTIs). The present study aims to assess the clinical significance of respiratory viruses in pragmatically selected adults in medical intensive care unit patients and to identify factors associated with viral respiratory viral tract infections (VRTIs). We conducted a prospective study on critically ill adults with suspected RTIs without recognized respiratory pathogens. Viral cultures with monoclonal antibody identification, in-house real-time polymerase chain reaction (PCR) for influenza virus, and FilmArray respiratory panel were used to detect viral pathogens. Multivariable logistic regression was applied to identify factors associated with VRTIs. Sixty-four (40.5%) of the included 158 critically ill adults had respiratory viruses detected in their respiratory specimens. The commonly detected viruses included influenza virus (20), followed by human rhinovirus/enterovirus (11), respiratory syncitial virus (9), human metapneumovirus (9), human parainfluenza viruses (8), human adenovirus (7), and human coronaviruses (2). The FilmArray respiratory panel detected respiratory viruses in 54 (34.6%) patients, but showed negative results for seven of 13 patients with influenza A/H3 infection. In the multivariable logistic regression model, patient characters associated with VRTIs included those aged < 65 years, household contact with individuals with upper RTI, the presence of fever, cough with sputum production, and sore throat. Respiratory viruses were not uncommonly detected in the pragmatically selected adults with critical illness. The application of multiplex PCR testing for respiratory viruses in selected patient population is a practical strategy, and the viral detection rate could be further improved by the patient characters recognized in this study.

Human Metapneumovirus Pneumonia Precipitating Acute Respiratory Distress Syndrome in an Adult Patient

Acute respiratory distress syndrome (ARDS) is often due to direct lung injury, trauma, surgery, or infection. Making a definitive diagnosis may be difficult initially, as clinical manifestations are nonspecific until the disease progresses. We present a case of human metapneumovirus (hMPV) pulmonary infection precipitating ARDS.

A 51-year-old woman presented with one week of pleuritic chest pain, dyspnea, wheezing, subjective fever, and productive cough prior to presentation. Her medical history was significant for human immunodeficiency virus (HIV) with an unknown CD4 count and viral load, pulmonary sarcoidosis, asthma, and being an active smoker. On admission, the patient was dyspneic and using accessory muscles to breathe. She was afebrile and hypotensive. Physical examination revealed bilateral diffuse crackles. Her white blood cell (WBC) count was 7.7 K/mcL. A chest radiograph demonstrated bilateral lung opacifications suggestive of pneumonia, possibly Pneumocystis jiroveci pneumonia (PJP). Broad-spectrum antibiotics, including PJP treatment, corticosteroids, and fluids, were started. The patient received approximately 4 liters of intravenous fluids; yet, she remained hypotensive and required norepinephrine. Chest computed tomography (CT) demonstrated bilateral consolidations. Arterial blood gas (ABG) showed a partial pressure of oxygen (PaO₂) of 55 mmHg. The patient was intubated for acute hypoxemic respiratory failure and had a PaO₂/fraction of inspired oxygen (FiO₂) < 100. Repeat ABG within 12 hours showed a potential of hydrogen (pH) of 7.34, partial pressure of carbon dioxide (pCO₂) of 42 mmHg, and a PaO₂ of 130 mmHg. Bronchoalveolar lavage revealed only hMPV. The patient was managed supportively and extubated three days later. She was discharged home without oxygen requirement.

hMPV causes respiratory infections, most commonly in the extremes of age and immunocompromised patients. The treatment is supportive. Our patient developed acute hypoxemic respiratory failure secondary to an hMPV infection. hMPV pneumonia should be considered as a differential diagnosis in patients with severe respiratory illness and ARDS in order to promote antibiotic stewardship.

Update in Viral Infections in the Intensive Care Unit

The advent of highly sensitive molecular diagnostic techniques has improved our ability to detect viral pathogens leading to severe and often fatal infections that require admission to the Intensive Care Unit (ICU). Viral infections in the ICU have pleomorphic clinical presentations including pneumonia, acute respiratory distress syndrome, respiratory failure, central or peripheral nervous system manifestations, and viral-induced shock. Besides de novo infections, certain viruses fall into latency and can be reactivated in both immunosuppressed and immunocompetent critically ill patients. Depending on the viral strain, transmission occurs either directly through contact with infectious materials and large droplets, or indirectly through suspended air particles (airborne transmission of droplet nuclei). Many viruses can efficiently spread within hospital environment leading to in-hospital outbreaks, sometimes with high rates of mortality and morbidity, thus infection control measures are of paramount importance. Despite the advances in detecting viral pathogens, limited progress has been made in antiviral treatments, contributing to unexpectedly high rates of unfavorable outcomes. Herein, we review the most updated data on epidemiology, common clinical features, diagnosis, pathogenesis, treatment and prevention of severe community- and hospital-acquired viral infections in the ICU settings.

Clinical impact of human metapneumovirus infections before and during the COVID-19 pandemic

BACKGROUND

The first outbreak of coronavirus disease 2019 (COVID-19) occurred in March 2020 in Europe, which is normally the peak incidence period of human metapneumovirus (HMPV) infections, implying cocirculation and potentially causing competition between them.

METHODS

We investigated differences in clinical characteristics and outcomes of HMPV infections in hospitalized patients before (January 2016-28 February, 2020) and HMPV and COVID-19 during part of the COVID-19 pandemic (28 February, 2020-1 April, 2020).

RESULTS

A total of 239 HMPV patients and 303 COVID-19 patients were included. Incidence of HMPV peaked in March. Despite a 324% increase in HMPV testing during the COVID-19 outbreak, incidence of HMPV remained stable. Clinical characteristics showed 25 (11%) ICU admissions and 14 (6%) deaths. History of myocardial infarction, higher age and lower BMI were independently associated with increased 30-day mortality. Clinical characteristics of HMPV-infected patients did not differ between the non-COVID-19 period and the examined COVID-19 period except for length of hospital stay (7 vs. 5 days). HMPV infection and COVID-19 shared many clinical features but HMPV was associated with female gender, elderly patients and chronic conditions (COPD and chronic heart failure). Clinical outcomes did not differ between the viruses during the COVID-19 period.

CONCLUSIONS

The clinical impact of HMPV infection did not change during the COVID-19 outbreak in terms of incidence and/or disease severity; hence, HMPV and SARS-CoV-2 are probably co-circulating independently. Despite the current clinical focus on the COVID-19 pandemic, clinicians should keep in mind that HMPV-infection may mimic COVID-19 and is also associated with serious adverse outcomes.

Clinical, Bronchoscopic, and Imaging Findings of e-Cigarette, or Vaping, Product Use-Associated Lung Injury Among Patients Treated at an Academic Medical Center

IMPORTANCE

e-Cigarette, or vaping, product use-associated lung injury (EVALI) has caused more than 2800 illnesses and 68 deaths in the United States. Better characterization of this novel illness is needed to inform diagnosis and management.

OBJECTIVE

To describe the clinical features, bronchoscopic findings, imaging patterns, and outcomes of EVALI.

DESIGN, SETTING, AND PARTICIPANTS

This case series of 31 adult patients diagnosed with EVALI between June 24 and December 10, 2019, took place at an academic medical center in Salt Lake City, Utah.

EXPOSURES

e-Cigarette use, also known as vaping.

MAIN OUTCOMES AND MEASURES

Symptoms, laboratory findings, bronchoscopic results, imaging patterns, and clinical outcomes.

RESULTS

Data from 31 patients (median [interquartile range] age, 24 [21-31] years) were included in the study. Patients were primarily men (24 [77%]) and White individuals (27 [87%]) who used e-cigarette products containing tetrahydrocannabinol (THC) (29 [94%]). Patients presented with respiratory (30 [97%]), constitutional (28 [90%]), and gastrointestinal (28 [90%]) symptoms. Serum inflammatory markers were elevated in all patients. Bronchoscopy was performed in 23 of 28 inpatients (82%) and bronchoalveolar lavage (BAL) revealed the presence of lipid-laden macrophages (LLMs) in 22 of 24 cases (91%). BAL samples tested positive for Pneumocystis jirovecii (3 patients [13%]), rhinovirus (2 patients [8%]), human metapneumovirus and Aspergillus (1 patient each [4%]); all except human metapneumovirus were determined to be false-positives or clinically inconsequential. The exclusive or dominant computed tomography (CT) pattern was organizing pneumonia in 23 of 26 cases (89%). Patients received antibiotics (26 [84%]) and corticosteroids (24 [77%]), and all survived; 20 patients (65%) seen in follow-up showed marked improvement, but residual symptoms (13 [65%]), radiographic opacities (8 [40%]), and abnormal pulmonary function tests (8 of 18 [44%]) were common.

CONCLUSIONS AND RELEVANCE

In this case series, patients with EVALI characteristically presented with a flu-like illness with elevated inflammatory markers, LLMs on BAL samples, and an organizing pneumonia pattern on CT imaging. Bronchoscopic testing for infection had a high incidence of false-positive results. Patients had substantial residual abnormal results at early follow-up. These data suggest a limited role for bronchoscopy in typical presentations of EVALI without risk factors for alternative diagnoses and the need for careful longitudinal follow-up.

Characteristics of human metapneumovirus infection in adults hospitalized for community-acquired influenza-like illness in France, 2012-2018: a retrospective observational study

Objectives

To describe the prevalence, clinical features and complications of human metapneumovirus (hMPV) infections in a population of adults hospitalized with influenza-like illness (ILI).

Methods

This was a retrospective, observational, multicenter cohort study using prospectively collected data from adult patients hospitalized during influenza virus circulation, for at least 24 h, for community-acquired ILI (with symptom onset <7 days). Data were collected from five French teaching hospitals over six consecutive winters (2012–2018). Respiratory viruses were identified by multiplex reverse transcription polymerase chain reaction (RT-PCR) on nasopharyngeal specimens. hMPV + patients were compared with hMPV– patients, influenza+ and respiratory syncytial virus (RSV)+ patients using multivariate logistic regressions. Primary outcome was the prevalence of hMPV in patients hospitalized for ILI.

Results

Among the 3148 patients included (1449 (46%) women, 1988 (63%) aged 65 and over; 2508 (80%) with chronic disease), at least one respiratory virus was detected in 1604 (51%, 95% confidence interval (CI) 49–53), including 100 cases of hMPV (100/3148, 3% 95% CI 3–4), of which 10 (10%) were viral co-infection. In the hMPV + patients, mean length of stay was 7 days, 62% (56/90) developed a complication, 21% (14/68) were admitted to intensive care unit and 4% (4/90) died during hospitalization. In comparison with influenza + patients, hMPV + patients were more frequently >65 years old (adjusted odds ratio (aOR) = 3.3, 95% CI 1.9–6.3) and presented more acute heart failure during hospitalization (aOR = 1.8, 95% CI 1.0–2.9). Compared with RSV + patients, hMPV + patients had less cancer (aOR = 0.4, 95% CI 0.2–0.9) and were less likely to smoke (aOR = 0.5, 95% CI 0.2–0.9) but had similar outcomes, especially high rates of respiratory and cardiovascular complications.

Conclusions

Adult hMPV infections mainly affect the elderly and patients with chronic conditions and are responsible for frequent cardiac and pulmonary complications similar to those of RSV infections. At-risk populations would benefit from the development of antivirals and vaccines targeting hMPV.

Burden of Community-Acquired Pneumonia and Unmet Clinical Needs

Community-acquired pneumonia (CAP) is the leading cause of death among infectious diseases and an important health problem, having considerable implications for healthcare systems worldwide. Despite important advances in prevention through vaccines, new rapid diagnostic tests and antibiotics, CAP management still has significant drawbacks. Mortality remains very high in severely ill patients presenting with respiratory failure or shock but is also high in the elderly. Even after a CAP episode, higher risk of death remains during a long period, a risk mainly driven by inflammation and patient-related co-morbidities. CAP microbiology has been altered by new molecular diagnostic tests that have turned viruses into the most identified pathogens, notwithstanding uncertainties about the specific role of each virus in CAP pathogenesis. Pneumococcal vaccines also impacted CAP etiology and thus had changed Streptococcus pneumoniae circulating serotypes. Pathogens from specific regions should also be kept in mind when treating CAP. New antibiotics for CAP treatment were not tested in severely ill patients and focused on multidrug-resistant pathogens that are unrelated to CAP, limiting their general use and indications for intensive care unit (ICU) patients. Similarly, CAP management could be personalized through the use of adjunctive therapies that showed outcome improvements in particular patient groups. Although pneumococcal vaccination was only convincingly shown to reduce invasive pneumococcal disease, with a less significant effect in pneumococcal CAP, it remains the best therapeutic intervention to prevent bacterial CAP. Further research in CAP is needed to reduce its population impact and improve individual outcomes.

Comparison of the Panther Fusion respiratory panels to routine methods for detection of viruses in upper and lower respiratory tract specimens

Viral respiratory infections remain a significant cause of morbidity and mortality in pediatric, elderly, and immunocompromised patients. The Panther Fusion respiratory panels consist of 3 separate multiplex assays that test for 1) influenza A, influenza B, and RSV; 2) parainfluenza virus types 1-4; or 3) adenovirus, human metapneumovirus, and rhinovirus. This study evaluated the performance of the Fusion assays for both upper and lower respiratory tract specimens in comparison to routine methods, including viral culture and targeted real-time polymerase chain reaction assays. Following discordant resolution, the Fusion assays demonstrated high overall correlation (98.6% [648/657]) with routine methods. In addition, prospective testing of respiratory specimens (n = 146) submitted for viral culture showed a ~10-fold increase in detection by the Fusion panels compared to viral culture (28.1% versus 2.7% positivity). The Fusion respiratory panels offer a flexible, more targeted approach to respiratory virus testing with a turnaround time comparable to other molecular assays.

Diagnosis of severe respiratory infections in immunocompromised patients

An increasing number of critically ill patients are immunocompromised. Acute hypoxemic respiratory failure (ARF), chiefly due to pulmonary infection, is the leading reason for ICU admission. Identifying the cause of ARF increases the chances of survival, but may be extremely challenging, as the underlying disease, treatments, and infection combine to create complex clinical pictures. In addition, there may be more than one infectious agent, and the pulmonary manifestations may be related to both infectious and non-infectious insults. Clinically or microbiologically documented bacterial pneumonia accounts for one-third of cases of ARF in immunocompromised patients. Early antibiotic therapy is recommended but decreases the chances of identifying the causative organism(s) to about 50%. Viruses are the second most common cause of severe respiratory infections. Positive tests for a virus in respiratory samples do not necessarily indicate a role for the virus in the current acute illness. Invasive fungal infections (Aspergillus, Mucorales, and Pneumocystis jirovecii) account for about 15% of severe respiratory infections, whereas parasites rarely cause severe acute infections in immunocompromised patients. This review focuses on the diagnosis of severe respiratory infections in immunocompromised patients. Special attention is given to newly validated diagnostic tests designed to be used on non-invasive samples or bronchoalveolar lavage fluid and capable of increasing the likelihood of an early etiological diagnosis.