Viral Pneumonia in Patients with Hematologic Malignancy or Hematopoietic Stem Cell Transplantation

Evaluation of pulmonary abnormalities in recipients of hematopoietic cell transplants and cellular therapies

Hematopoietic cell transplant (HCT) and chimeric antigen receptor T-cell (CAR-T) therapy recipients are susceptible to multiple pulmonary complications that are caused by infectious and noninfectious processes. Numerous variables can be associated with specific pulmonary diseases including time from transplantation, presence of graft versus host disease (GVHD), underlying disease, and prolonged neutropenia and lymphocytopenia. Most pulmonary complications are infectious in origin, with bacterial pneumonia remaining the most common pulmonary infection, particularly before neutrophil engraftment. Invasive fungal infections continue to affect this patient population even when antifungal prophylaxis is used. Noninfectious pulmonary complications include a wide differential of pathologies in this population, and as clinical presentations of these various pulmonary disorders often overlap, clinicians frequently will use a multidisciplinary approach in diagnosing these abnormalities. Radiography, particularly with chest computed tomography (CT) imaging, is an essential tool in identifying pulmonary pathology and potential sources. While standard microbiological cultures of respiratory specimens are still utilized, their role is limited by low sensitivity and diagnostic yield. The likelihood of obtaining a diagnosis can be improved by using other microbiological assays, including fungal antigen tests and molecular diagnostic methods, particularly if specimens are collected via bronchoscopy. This review will highlight the more common causes of pulmonary diseases encountered after HCT and CAR-T and will examine the different methods in their diagnosis.

Airway disease in hematologic malignancies

INTRODUCTION

Hematologic malignancies are cancers of the blood, bone marrow and lymph nodes and represent a heterogenous group of diseases that affect people of all ages. Treatment generally involves chemotherapeutic or targeted agents that aim to kill malignant cells. In some cases, hematopoietic stem cell transplantation (HCT) is required to replenish the killed blood and stem cells. Both disease and therapies are associated with pulmonary complications. As survivors live longer with the disease and are treated with novel agents that may result in secondary immunodeficiency, airway diseases and respiratory infections will increasingly be encountered. To prevent airways diseases from adding to the morbidity of survivors or leading to long-term mortality, improved understanding of the pathogenesis and treatment of viral bronchiolitis, BOS, and bronchiectasis is necessary.

AREAS COVERED

This review focuses on viral bronchitis, BOS and bronchiectasis in people with hematological malignancy. Literature was reviewed from Pubmed for the areas covered.

EXPERT OPINION

Airway disease impacts significantly on hematologic malignancies. Viral bronchiolitis, BOS and bronchiectasis are common respiratory manifestations in hematological malignancy. Strategies to identify patients early in their disease course may improve the efficacy of treatment and halt progression of lung function decline and improve quality of life.

Clinical Application of Metagenomic Next-Generation Sequencing in Patients with Hematologic Malignancies Suffering from Sepsis

Background: Sepsis remains a common but fatal complication among patients with immune suppression. We aimed to investigate the performance of metagenomic next-generation sequencing (mNGS) compared with standard microbiological diagnostics in patients with hematologic malignancies. Methods: We performed a prospective study from June 2019 to December 2019. Adult patients with hematologic malignancies and a clinical diagnosis of sepsis were enrolled. Conventional diagnostic methods included blood cultures, serum galactomannan for Aspergillus, cryptococcal antigen and cytomegalovirus (CMV) viral loads. Blood samples for mNGS were collected within 24 h after hypotension developed. Results: Of 24 patients enrolled, mNGS and conventional diagnostic methods (blood cultures, serology testing and virus RT-PCR) reached comparable positive results in 9 cases. Of ten patients, mNGS was able to identify additional pathogens compared with conventional methods; most of the pathogens were virus. Conclusion: Our results show that mNGS may serve as adjunctive diagnostic tool for the identification of pathogens of hematologic patients with clinically sepsis.

Pulmonary Complications After Pediatric Stem Cell Transplant

The number of disorders that benefit from hematopoietic stem cell transplantation (HSCT) has increased, causing the overall number of HSCT to increase accordingly. Disorders treated by HSCT include malignancy, benign hematologic disorders, bone marrow failure syndromes, and certain genetic diagnoses. Thus, understanding the complications, diagnostic workup of complications, and subsequent treatments has become increasingly important. One such category of complications includes the pulmonary system. While the overall incidence of pulmonary complications has decreased, the morbidity and mortality of these complications remain high. Therefore, having a clear differential diagnosis and diagnostic workup is imperative. Pulmonary complications can be subdivided by time of onset and whether the complication is infectious or non-infectious. While most infectious complications have clear diagnostic criteria and treatment courses, the non-infectious complications are more varied and not always well understood. This review article discusses pulmonary complications of HSCT recipients and outlines current knowledge, gaps in knowledge, and current treatment of each complication. This article includes some adult studies, as there is a significant paucity of pediatric data.

Radiological, epidemiological and clinical patterns of pulmonary viral infections

Respiratory viruses are the most common causes of acute respiratory infections. However, identification of the underlying viral pathogen may not always be easy. Clinical presentations of respiratory viral infections usually overlap and may mimic those of diseases caused by bacteria. However, certain imaging morphologic patterns may suggest a particular viral pathogen as the cause of the infection. Although definitive diagnosis cannot be made on the basis of clinical or imaging features alone, the use of a combination of clinical and radiographic findings can substantially improve the accuracy of diagnosis. The purpose of this review is to present the clinical, epidemiological and radiological patterns of lower respiratory tract viral pathogens providing a comprehensive approach for their diagnosis and identification in hospitals and community outbreaks.

Challenges of Hematopoietic Stem Cell Transplantation in the Era of COVID-19

The coronavirus disease 2019 (COVID-19) pandemic raised unprecedented concerns in the hematopoietic stem cell transplant community. The diagnosis of COVID-19 in these transplant recipients may require extensive laboratory testing and high clinical suspicion, as atypical clinical manifestations or other respiratory viral infections are common in this patient population. The underlying malignancies, immunosuppressed state, frequently observed coinfections, and advanced age in some patients may also predispose them to worse clinical outcomes. Similar outcomes have been previously described with other human coronaviruses, including the severe acute respiratory syndrome coronavirus and the Middle East respiratory syndrome coronavirus. Many hematopoietic stem cell transplant organizations have issued elaborative guidelines that aim to prevent transmission and hence adverse patient outcomes. All potential donors are thoroughly screened, and donated products are cryopreserved in advance. Potential hematopoietic stem cell transplant recipients are also screened, and most nonurgent transplant cases with low risk of progression and/or death are deferred. Current hematopoietic stem cell transplant recipients should adhere to precaution and isolation measures, while their transplant units should also follow strict safety protocols, similar to other infectious outbreaks. The prolonged susceptibility of hematopoietic stem cell transplant recipients to respiratory viral infections might necessitate extending these measures even after the peak of the outbreak until a gradually return to normality is possible.

Characteristics of respiratory virus infections in autologous hematopoietic stem cell transplantation patients, a prospective study, Bern, Switzerland, 2015-2017

BACKGROUND

The epidemiology of respiratory virus infections (RVI) in patients undergoing autologous haematopoietic stem cell transplantation (auto-SCT) is not well described.

METHODS

Our goal was to describe the epidemiology of respiratory virus infections (RVI) in patients undergoing autologous haematopoietic stem cell transplantation (auto-SCT) in a single tertiary centre observation study during two respiratory virus seasons (2015-2017). All symptomatic auto-SCT patients were tested for RVI by nasopharyngeal swab.

RESULTS

156 transplantation episodes were included, 69% were male and, the median age was 57 years. We detected 19 RVIs in 156 transplantation episodes (12%). The median time to RVI after hospitalization was 13 days [IQR 7-13] and 15/19 (79%) had a possible nosocomial origin (occurrence ≥ 5 days after admission). The nosocomial infections included 5/15 (33%) 'severe' RVIs (3 influenza viruses, 1 parainfluenza virus, and 1 adenovirus) as well as 10/15 (66%) non-severe virus infections (including human rhinovirus and human coronavirus).

CONCLUSION

In approximately 10% of auto-SCT transplantation episodes, an RVI with likely nosocomial origin was detected and included 'severe viruses' such as influenza. Our study suggests that infection prevention measures in auto-SCT patients can be improved.

ABBREVIATIONS

AdV: adenovirus; ALL: acute lymphatic leukaemia; AML: acute myeloid leukaemia; auto-SCT: autologous haematopoietic stem cell transplantation; hCoV: human coronavirus; HD: Hodgkin's disease; hMPV: human metapneumovirus; HRV: human rhinovirus; HSCT: allogeneic haematopoietic stem cell transplantation; IQR: interquartile range; GCT: germ cell tumour; MM: multiple myeloma; NHL: non-Hodgkin lymphoma; PIV: parainfluenza virus; RSV: respiratory syncytial virus.

Critical Care of Hematopoietic Stem Cell Transplant Patients

Life-threatening complications are frequent after hematopoietic stem cell transplant (HSCT), and optimum critical care is essential to ensuring good outcomes. The immunologic consequences of HSCT result in a markedly different host response to critical illness. Infection is the most common cause of critical illness but noninfectious complications are frequent. Respiratory failure or sepsis are the typical presentations but the sequelae of HSCT can affect nearly any organ system. Pattern recognition can facilitate anticipation and early intervention in post-HSCT critical illness. HSCT critical care is a multidisciplinary endeavor. Continued investigation and focus on process improvement will continue to improve outcomes.

ICU Complications of Hematopoietic Stem Cell Transplant, Including Graft vs Host Disease

Hematopoietic stem cell transplant (HSCT) is an essential treatment modality for many malignant and non-malignant hematologic diseases. Advances in HSCT techniques have dramatically decreased peri-transplant morbidity and mortality, but it remains a high-risk procedure, and a significant number of patients will require critical care during the transplant process. Complications of HSCT are both infectious and non-infectious, and the intensivist must be familiar with common infections, the management of neutropenic sepsis and septic shock, the management of respiratory failure in the immunocompromised host, and a plethora of HSCT-specific complications. Survival from critical illness after HSCT is improving, but the mortality rate remains unacceptably high. Continued research and optimization of critical care provision in this population should continue to improve outcomes.

Acute Respiratory Distress Syndrome in Cancer Patients

Acute respiratory distress syndrome (ARDS) is a heterogeneous form of acute, diffuse lung injury that is characterized by dysregulated inflammation, increased alveolar-capillary interface permeability, and non-cardiogenic pulmonary edema. In the general population, the incidence and mortality associated with ARDS over the last two decades have steadily declined in parallel with optimized approaches to pneumonia and other underlying causes of ARDS as well as increased utilization of multimodal treatment strategies that include lung-protective ventilation. In the cancer settings, significant declines in the incidence and mortality of ARDS over the past two decades have also been reported, although these rates remain significantly higher than those in the general population. Epidemiologic studies identify infection, including disseminated fungal pneumonias, as a major underlying cause of ARDS in the cancer setting. More than half of cancer patients who develop ARDS will not survive to hospital discharge. Those who do survive often face a protracted and often incomplete recovery, resulting in significant long-term physical, psychological, and cognitive sequelae. The residual organ dysfunction and poor functional status after ARDS may delay or preclude subsequent cancer treatments. As such, close collaboration between the critical care physicians and oncology team is essential in identifying and reversing the underlying causes and optimizing treatments for cancer patients with ARDS. This chapter reviews the diagnosis and common causes of ARDS in cancer and gives an update on the general management principles for cancer patients with ARDS in the ICU.

Future Research Directions in Pneumonia. NHLBI Working Group Report

Pneumonia is a complex pulmonary disease in need of new clinical approaches. Although triggered by a pathogen, pneumonia often results from dysregulations of host defense that likely precede infection. The coordinated activities of immune resistance and tissue resilience then dictate whether and how pneumonia progresses or resolves. Inadequate or inappropriate host responses lead to more severe outcomes such as acute respiratory distress syndrome and to organ dysfunction beyond the lungs and over extended time frames after pathogen clearance, some of which increase the risk for subsequent pneumonia. Improved understanding of such host responses will guide the development of novel approaches for preventing and curing pneumonia and for mitigating the subsequent pulmonary and extrapulmonary complications of pneumonia. The NHLBI assembled a working group of extramural investigators to prioritize avenues of host-directed pneumonia research that should yield novel approaches for interrupting the cycle of unhealthy decline caused by pneumonia. This report summarizes the working group's specific recommendations in the areas of pneumonia susceptibility, host response, and consequences. Overarching goals include the development of more host-focused clinical approaches for preventing and treating pneumonia, the generation of predictive tools (for pneumonia occurrence, severity, and outcome), and the elucidation of mechanisms mediating immune resistance and tissue resilience in the lung. Specific areas of research are highlighted as especially promising for making advances against pneumonia.

Epidemiology and clinical impact of viral, atypical, and fungal respiratory pathogens in symptomatic immunocompromised patients: a two-center study using a multi-parameter customized respiratory Taqman® array card

The prevalence of respiratory viruses in immunocompromised adult patients and the association with clinical outcomes is still underexplored. Our goal was to assess the epidemiology and the potential clinical impact of respiratory viral infections in a high-risk patient population. Two large hospitals performed a respiratory Taqman array card (TAC), targeting 24 viruses, 8 bacteria, and 2 fungi simultaneously, on 435 samples from 397 symptomatic immunocompromised patients. Clinical details were collected retrospectively using a structured case report form. An overall positivity rate of 68% was found (51% mono- and 17% co-infections). Pathogen distribution was as follows: influenza A (20.7%), rhinoviruses (15.2%), coronaviruses (7.8%), Pneumocystis jirovecii (7.4%), RSV (7.1%), and CMV (6.0%) were the most frequently encountered, followed by HSV (5.5%), hMPV (4.4%), parainfluenza viruses (3.9%), influenza B (3.7%), and Aspergillus species (3.7%). Other pathogens were not detected or detected only in ≤ 1% of samples. Hospital and ICU admission rates were 84% and 11%, respectively. The presence of a pathogen was strongly associated with higher need for supplemental oxygen (p = 0.001), but it had no impact on ICU admission, mechanical ventilation requirement, antibacterial therapy, or mortality. In conclusion, our study described the epidemiology of respiratory pathogens in a large group of symptomatic immunocompromised patients and provides evidence of a relationship between pathogen detection and the need for supplemental oxygen. This association was still found after the exclusion of the results positive for influenza viruses, suggesting that non-influenza viruses contribute to severe respiratory illness in patients with compromised immunity.

Bronchoalveolar lavage with pediatric flexible fibreoptic bronchoscope in pediatric haematopoietic stem cell transplant patients: Nursing considerations for operative complications

PURPOSE

Bronchoalveolar lavage (BAL) with pediatric flexible fibreoptic bronchoscopy (FB) is used for diagnostic and therapeutic purposes in pediatric haematopoietic stem cell transplant (HSCT) patients with pulmonary complications. The aim of our study was to evaluate complications in pediatric HSCT patients undergoing BAL/FB and to explore the nursing emphases on complications.

DESIGN AND METHODS

We performed a retrospective, case-controlled study to evaluate perioperative complications of HSCT children. BAL/FB was conducted for 42 children with HSCT who experienced pulmonary complications between January 2017 and January 2018 within a tertiary hospital. Forty patients diagnosed with general pneumonia were randomly selected during the same period and served as the control group. We analyzed the signs and symptoms of all patients and compared the operative complications between the two groups. Furthermore, we presented the methods used to manage complications.

RESULTS

The presence of cough, lung rales, and imaging findings in the HSCT patients was significantly different from that of the control group (p < 0.0001). The complication rate was 66.67% (28/42) in the HSCT group and 22.5% (9/40) in the control group, and the difference was significant (p < 0.0001). Twelve out of 42 HSCT patients experienced airway mucosal bleeding (28.57%), and six had transient fever (14.29%). The topical use of epinephrine diluted saline (1:10,000) was highly effective for controlling airway mucosal bleeding without causing fluctuations in blood pressure.

PRACTICE IMPLICATIONS

There were more perioperative complications in the HSCT patients than in the general pneumonia patients who underwent BAL/FB. Airway mucosal bleeding was a key focus of perioperative nursing in HSCT patients undergoing bronchoscopy as main complication. BAL with the use of epinephrine diluted saline (1:10,000) effectively decreased airway mucosal bleeding.

Respiratory Infections

Pneumonia is defined as the presence of a new pulmonary infiltrate on radiologic imaging in the patient with appropriate clinical symptoms such as fever, cough, production of purulent sputum, shortness of breath and/or hypoxia, in the absence of pulmonary edema [1, 2].

Managing pulmonary complications in allogeneic hematopoietic stem cell transplantation

Introduction: Progress in allogeneic hematopoietic stem cell transplantation (HSCT) procedures has been associated with improved survival in HSCT recipients. However, they have also brought to light organ-specific complications, especially pulmonary complications. In this setting, pulmonary complications are consistently associated with poor outcomes, and improved management of these complications is required. Areas covered: We review the multiple infectious and noninfectious lung complications that occur both early and late after allogeneic HSCT. This includes the description of these complications, risk factors, diagnostic approach and outcome. A literature search was performed using PubMed-indexed journals. Expert commentary: Multiple lung complications after allogeneic HSCT can be diagnosed concomitantly and require a multidisciplinary approach. A specific clinical evaluation including a precise analysis of a lung CT scan is necessary. Management of these lung complications, especially the noninfectious ones, is impaired by the lack of prospective, randomized control trials, suggesting preventive strategies should be developed.

Transmission and Control of Respiratory Viral Infections in the Healthcare Setting

Purpose of the review

Viral respiratory infections have been recognized as a cause of severe illness in immunocompromised and non-immunocompromised hosts. This acknowledgement is a consequence of improvement in diagnosis and better understanding of transmission. Available vaccines and antiviral drugs for prophylaxis and treatment have been developed accordingly. Viral respiratory pathogens are increasingly recognized as nosocomial pathogens as well. The purpose of this review is to describe the most frequent and relevant nosocomial viral respiratory infections, their mechanisms of transmission and the infection control measures to prevent their spread in the healthcare setting.

Recent findings

Although most mechanisms of transmission and control measures of nosocomial viral infections are already known, improved diagnostic tools allow better characterization of these infections and also lead to the discovery of new viruses such as the coronavirus, which is the cause of the Middle East Respiratory Syndrome, or the human bocavirus. Also, the ability to understand better the impact, dissemination and prevention of these viruses, allows us to improve the measures to prevent these infections.

Summary

Healthcare viral respiratory infections increase patient morbidity. Each virus has a different mechanism of transmission; therefore, early detection and prompt implementation of infection control measures are very important in order to avoid their transmission in the hospital setting.

RSV Infection in Human Macrophages Promotes CXCL10/IP-10 Expression during Bacterial Co-Infection

Respiratory syncytial virus (RSV), a major etiologic agent of acute lower respiratory infection constitutes the most important cause of death in young children worldwide. Viral/bacterial mixed infections are related to severity of respiratory inflammatory diseases, but the underlying mechanisms remain poorly understood. We have previously investigated the intracellular mechanisms that mediate the immune response in the context of influenza virus/Streptococcus pneumoniae (Sp) co-infection using a model of human monocyte-derived macrophages (MDMs). Here, we set up and characterized a similar model of MDMs to investigate different scenarios of RSV infection and co-infection with Sp. Our results suggest that Sp contributes to a faster and possibly higher level of CXCL10/IP-10 expression induced by RSV infection in human MDMs.