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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.

Pseudomonas aeruginosa is a Gram-negative bacterial pathogen that is a common cause of nosocomial infections, particularly pneumonia, infection in immunocompromised hosts, and in those with structural lung disease such as cystic fibrosis. Epidemiological studies have identified increasing trends of antimicrobial resistance, including multi-drug resistant (MDR) isolates in recent years. P. aeruginosa has several virulence mechanisms that increase its ability to cause severe infections, such as secreted toxins, quorum sensing and biofilm formation. Management of P. aeruginosa infections focuses on prevention when possible, obtaining cultures, and prompt initiation of antimicrobial therapy, occasionally with combination therapy depending on the clinical scenario to ensure activity against P. aeruginosa . Newer anti-pseudomonal antibiotics are available and are increasingly being used in the management of MDR P. aeruginosa .

SARS-CoV-2 remdesivir resistance mutations have been generated in vitro but have not been reported in patients receiving treatment with the antiviral agent. We present a case of an immunocompromised patient with acquired B-cell deficiency who developed an indolent, protracted course of SARS-CoV-2 infection. Remdesivir therapy alleviated symptoms and produced a transient virologic response, but her course was complicated by recrudescence of high-grade viral shedding. Whole genome sequencing identified a mutation, E802D, in the nsp12 RNA-dependent RNA polymerase, which was not present in pre-treatment specimens. In vitro experiments demonstrated that the mutation conferred a ~6-fold increase in remdesivir IC 50 but resulted in a fitness cost in the absence of remdesivir. Sustained clinical and virologic response was achieved after treatment with casirivimab-imdevimab. Although the fitness cost observed in vitro may limit the risk posed by E802D, this case illustrates the importance of monitoring for remdesivir resistance and the potential benefit of combinatorial therapies in immunocompromised patients with SARS-CoV-2 infection. Here, the authors identify and validate the emergence of a SARS-CoV-2 resistance mutation to Remdesivir, associated with virological recrudesce in an immunocompromised patient with persistent COVID-19.

ABSTRACTHuman respiratory syncytial virus (RSV) belongs to the recently defined Pneumoviridae family, Orthopneumovirus genus. It is a negative sense, single stranded RNA virus that results in epidemics of respiratory infections that typically peak in the winter in temperate climates and during the rainy season in tropical climates. Generally, one of the two genotypes (A and B) predominates in a single season, alternating annually, although regional variation occurs. RSV is a cause of disease and death in children, older people, and immunocompromised patients, and its clinical effect on adults admitted to hospital is clarified with expanded use of multiplex molecular assays. Among adults, RSV produces a wide range of clinical symptoms including upper respiratory tract infections, severe lower respiratory tract infections, and exacerbations of underlying disease. Here we discuss the latest evidence on the burden of RSV related disease in adults, especially in those with immunocompromise or other comorbidities. We review current therapeutic and prevention options, as well as those in development.

ObjectiveTo evaluate tofacitinib's effect upon pneumococcal and influenza vaccine immunogenicity.MethodsWe conducted two studies in patients with rheumatoid arthritis using the 23-valent pneumococcal polysaccharide vaccine (PPSV-23) and the 2011–2012 trivalent influenza vaccine. In study A, tofacitinib-naive patients were randomised to tofacitinib 10 mg twice daily or placebo, stratified by background methotrexate and vaccinated 4 weeks later. In study B, patients already receiving tofacitinib 10 mg twice daily (with or without methotrexate) were randomised into two groups: those continuing (‘continuous’) or interrupting (‘withdrawn’) tofacitinib for 2 weeks, and then vaccinated 1 week after randomisation. In both studies, titres were measured 35 days after vaccination. Primary endpoints were the proportion of patients achieving a satisfactory response to pneumococcus (twofold or more titre increase against six or more of 12 pneumococcal serotypes) and influenza (fourfold or more titre increase against two or more of three influenza antigens).ResultsIn study A (N=200), fewer tofacitinib patients (45.1%) developed satisfactory pneumococcal responses versus placebo (68.4%), and pneumococcal titres were lower with tofacitinib (particularly with methotrexate). Similar proportions of tofacitinib-treated and placebo-treated patients developed satisfactory influenza responses (56.9% and 62.2%, respectively), although fewer tofacitinib patients (76.5%) developed protective influenza titres (≥1:40 in two or more of three antigens) versus placebo (91.8%). In study B (N=183), similar proportions of continuous and withdrawn patients had satisfactory responses to PPSV-23 (75.0% and 84.6%, respectively) and influenza (66.3% and 63.7%, respectively).ConclusionsAmong patients starting tofacitinib, diminished responsiveness to PPSV-23, but not influenza, was observed, particularly in those taking concomitant methotrexate. Among existing tofacitinib users, temporary drug discontinuation had limited effect upon influenza or PPSV-23 vaccine responses.Trial registration numbersNCT01359150, NCT00413699.

The immune response to viral infection is a delicate balance. By perturbing this balance, immunodeficiencies are expected to influence within-host viral evolution. Indeed, the presence of immunocompromised hosts has been argued to be a source of novel viral variants in some infectious diseases, including SARS-CoV-2. However, these arguments rest upon between-host models and so the role of immunodeficiencies on within-host evolution in primary infections is poorly understood. Using a mechanistic immunological model, here we consider how different immunodeficiencies shape the orchestration of the immune response during primary infection. We study how this alters the viral fitness landscape, thus speeding and slowing viral evolution. We show that during acute infections, while immunodeficiencies in neutrophils and interferon initially speed viral evolution, by the time the infection is cleared, mutations are at lower frequencies than in immunocompetent hosts. In persistent infections, we show that while T cell deficiencies slow viral evolution, interleukin-6 and macrophage deficiencies speed viral evolution. Finally, we show that positive epistatic interactions arising due to the immunological response will accelerate the evolution of viral mutations affecting the ability of virions to evade different aspects of the immune response and to enter host cells.

Patients can be immunocompromised from a diverse range of disease and treatment factors, including malignancies, autoimmune disorders and their treatments, and organ and stem-cell transplantation. Infections are a leading cause of morbidity and mortality in immunocompromised patients, and the disease treatment landscape is continually evolving. Despite being a critical but preventable and curable adverse event, the reporting of infection events in randomised trials lacks sufficient detail while inconsistency of categorisation and definition of infections in observational and registry studies limits comparability and future pooling of data. A core reporting dataset consisting of category, site, severity, organism, and endpoints was developed as a minimum standard for reporting of infection events in immunocompromised patients across study types. Further additional information is recommended depending on study type. The standardised reporting of infectious events and attributable complications in immunocompromised patients will improve diagnostic, treatment, and prevention approaches and facilitate future research in this patient group.

The adjuvanted recombinant zoster vaccine (Shingrix) can prevent herpes zoster in older adults and autologous haemopoietic stem cell transplant recipients. We evaluated the safety and immunogenicity of this vaccine in adults with haematological malignancies receiving immunosuppressive cancer treatments. In this phase 3, randomised, observer-blind, placebo-controlled study, done at 77 centres worldwide, we randomly assigned (1:1) patients with haematological malignancies aged 18 years and older to receive two doses of the adjuvanted recombinant zoster vaccine or placebo 1–2 months apart during or after immunosuppressive cancer treatments, and stratified participants according to their underlying diseases. The co-primary objectives of the study were the evaluation of safety and reactogenicity of the adjuvanted recombinant zoster vaccine compared with placebo from the first vaccination up to 30 days after last vaccination in all participants; evaluation of the proportion of participants with a vaccine response in terms of anti-glycoprotein E humoral immune response to the adjuvanted recombinant zoster vaccine at month 2 in all participants, excluding those with non-Hodgkin B-cell lymphoma and chronic lymphocytic leukaemia; and evaluation of the anti-glycoprotein E humoral immune responses to the vaccine compared with placebo at month 2 in all participants, excluding those with non-Hodgkin B-cell lymphoma and chronic lymphocytic leukaemia. We assessed immunogenicity in the per-protocol cohort for immunogenicity and safety in the total vaccinated cohort. The study is registered with ClinicalTrials.gov, number NCT01767467, and with the EU Clinical Trials Register, number 2012-003438-18. Between March 1, 2013, and Sept 10, 2015, we randomly assigned 286 participants to adjuvanted recombinant zoster vaccine and 283 to placebo. 283 in the vaccine group and 279 in the placebo group were vaccinated. At month 2, 119 (80·4%, 95% CI 73·1–86·5) of 148 participants had a humoral vaccine response to adjuvanted recombinant zoster vaccine, compared with one (0·8%, 0·0–4·2) of 130 participants in the placebo group, and the adjusted geometric mean anti-glycoprotein E antibody concentration was 23 132·9 mIU/mL (95% CI 16 642·8–32 153·9) in the vaccine group and 777·6 mIU/mL (702·8–860·3) in the placebo group (adjusted geometric mean ratio 29·75, 21·09–41·96; p<0·0001) in all patients, excluding those with non-Hodgkin B-cell lymphoma and chronic lymphocytic leukaemia. Humoral and cell-mediated immune responses persisted above baseline until month 13 in all strata and, as expected, vaccine was more reactogenic than placebo (within 7 days after vaccination pain was reported by 221 [79·5%] of 278 vaccine group participants and 45 [16·4%] of 274 placebo group participants; fatigue was reported by 162 [58·3%] of 278 vaccine group participants and 102 [37·2%] of 274 placebo group participants). Incidences of unsolicited or serious adverse events, potential immune-mediated diseases, disease-related events, and fatal serious adverse events were similar between the groups. The immunocompromised adult population with haematological malignancies is at high risk for herpes zoster. The adjuvanted recombinant zoster vaccine, which is currently licensed in certain countries for adults aged 50 years and older, is likely to benefit this population. GlaxoSmithKline Biologicals SA.

Purpose Advances in therapeutic care are leading to an increase in the number of patients living with overt immunosuppression. These patients are at risk of cytomegalovirus (CMV) infection and disease that can lead to or develop during ICU admission. This manuscript aims to describe the clinical presentation, risk factors, and management of CMV infection and disease in this patient population. Methods We conducted a literature search in PubMed up to April 2024, focusing on CMV infection and disease in patients with overt immunosuppression (hematopoietic stem cell and solid organ transplantation, solid or hematologic malignancies, HIV infection, immunosuppressive drugs, including corticosteroids, and primary immunodeficiencies) admitted to the intensive care unit (ICU). As there is limited ICU-specific data on CMV in immunosuppressed patients, many of the findings were extrapolated from the general literature. Results CMV infection and disease in immunocompromised critically ill patients is associated with increased mortality and presents significant management challenges. Clinical manifestations are diverse, shaped by the underlying immune deficiency and primary disease. Pneumonia and encephalitis are among the most severe CMV end-organ diseases. CMV infection may also increase the risk of secondary infections and induce life-threatening conditions, such as thrombotic microangiopathy. Importantly, CMV reactivation is not synonymous with CMV disease, and qPCR testing of body fluids cannot reliably differentiate between viral shedding and tissue-invasive infection, which requires histopathological confirmation. Ganciclovir is commonly the first-line anti-viral, though maribavir shows potential for patients unresponsive to other antivirals. Identifying patients who require prophylactic or preemptive antiviral therapy is essential. Conclusions CMV infection and disease in critically ill immunocompromised patients pose a unique challenge for intensivists. The broad spectrum of clinical presentations and the difficulty in distinguishing CMV-related symptoms from other causes require a high level of clinical suspicion. Accurate interpretation of nucleic acid load levels and careful evaluation of CMV’s pathogenic role when it is found are critical. Further studies focusing specifically on CMV infection and disease in critically ill immunocompromised patients are needed to optimize management strategies.