Pneumonia is the leading cause of death from infection in the United States,¹ and timely empirical antibiotic therapy against the most likely pathogens is a cornerstone of care. However, causative pathogens are rarely identified,² leaving uncertainty in the choice of empirical antibiotic therapy. For patients hospitalized for community-onset pneumonia, this uncertainty has been magnified by the emergence of resistant organisms, chiefly methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa. The concept of health care–associated pneumonia, intended to assist clinicians in risk assessment,³ likely contributed to the overuse of broad-spectrum antibiotics.^4,5 Consequently, although fewer than 5% of hospitalized patients have resistant organisms detected, more than one-third receive broad-spectrum antibiotics.⁶

Background: Understanding of the diagnosis and treatment of adults with community-acquired pneumonia (CAP) has evolved thanks to new evidence, experience, and emerging technologies. This document updates evidence-based clinical practice guidelines on four key questions for the diagnosis and management of adult patients with CAP. Methods: A multidisciplinary panel integrated systematic reviews of comparative evidence with other relevant research and clinical experience, then applied Grading of Recommendations, Assessment, Development and Evaluation (GRADE) methodology to produce recommendations using the Evidence to Decision Framework. Results: The panel formulated clinical recommendations that address questions related to CAP, including lung ultrasound for diagnosis, empiric antibacterial therapy if a test for a respiratory virus is positive, antibiotic duration, and the use of systemic corticosteroids. Conclusions: The panel formulated and provided the rationale for recommendations on selected diagnostic and treatment strategies for adult patients with CAP.

Rationale: The relationship between air pollution and pneumonia is poorly understood. Objectives: To examine relationships between short-term air pollution exposure and number and severity of pneumonia cases along the Wasatch Front in Utah, a region with periodic high levels of outdoor air pollution. Methods: We applied time-stratified case–crossover analyses with distributed lag to patients presenting to seven emergency departments with pneumonia over a 2-year period. We compared levels of particulate matter less than or equal to 2.5 μm in aerodynamic diameter, nitrogen dioxide, and ozone at patient residences with emergency department cases, hospitalizations, objectively defined severe pneumonia, and mortality. We calculated direct cost impacts of particulate matter less than or equal to 2.5 μm in aerodynamic diameter reduction. Results: We evaluated 4,336 pneumonia cases in seven hospitals. Among adults aged 65 years and older, we found consistently positive associations between particulate matter less than or equal to 2.5 μm in aerodynamic diameter within 6 days of presentation and instances of pneumonia (Lag Day 1 adjusted odds ratio, 1.35 per 10 μg/m3 over 12 μg/m3; 95% confidence interval, 1.16–1.57), severe pneumonia (Lag Day 1 adjusted odds ratio, 1.38; 95% confidence interval, 1.06–1.80), and inpatient mortality (Lag Day 5 adjusted odds ratio, 1.50; 95% confidence interval, 1.03–2.16). Smaller associations were found between nitrogen dioxide exposure and pneumonia occurrence, severity, and inpatient and 30-day mortality. Ozone exposure was modestly associated with increased instance and severity of pneumonia in younger adults. Particulate matter less than or equal to 2.5 μm in aerodynamic diameter and nitrogen dioxide effects were greatest in colder months, and ozone effects were greatest in warmer months. Reduction of particulate matter less than or equal to 2.5 μm in aerodynamic diameter levels to less than 12.0 mg/m3 could prevent 76–112 cases of pneumonia per year in these hospitals serving approximately half of the Wasatch Front’s population, reducing direct medical facility costs by $807,000 annually. Conclusions: Among older adults, short-term ambient particulate matter less than or equal to 2.5 μm in aerodynamic diameter exposure is associated with more emergency department visits and hospitalizations for pneumonia, severe pneumonia, increased mortality, and increased healthcare costs. Nitrogen dioxide and ozone modestly increase pneumonia risk and illness severity.

Pneumonia imposes a significant clinical burden on people with immunocompromising conditions. Millions of individuals live with compromised immunity because of cytotoxic cancer treatments, biological therapies, organ transplants, inherited and acquired immunodeficiencies, and other immune disorders. Despite broad awareness among clinicians that these patients are at increased risk for developing infectious pneumonia, immunocompromised people are often excluded from pneumonia clinical guidelines and treatment trials. The absence of a widely accepted definition for immunocompromised host pneumonia is a significant knowledge gap that hampers consistent clinical care and research for infectious pneumonia in these vulnerable populations. To address this gap, the American Thoracic Society convened a workshop whose participants had expertise in pulmonary disease, infectious diseases, immunology, genetics, and laboratory medicine, with the goal of defining the entity of immunocompromised host pneumonia and its diagnostic criteria.

Despite efforts to reduce antibiotic prescribing for acute respiratory infections (ARIs), information on factors that drive prescribing is limited. To examine trends in antibiotic prescribing in the Veterans Affairs population over an 8-year period and to identify patient, provider, and setting sources of variation. Retrospective, cross-sectional study. All emergency departments and primary and urgent care clinics in the Veterans Affairs health system. All patient visits between 2005 and 2012 with primary diagnoses of ARIs that typically had low proportions of bacterial infection. Patients with infections or comorbid conditions that indicated antibiotic use were excluded. Overall antibiotic prescription; macrolide prescription; and patient, provider, and setting characteristics extracted from the electronic health record. The proportion of 1 million visits with ARI diagnoses that resulted in antibiotic prescriptions increased from 67.5% in 2005 to 69.2% in 2012 (P < 0.001). The proportion of macrolide antibiotics prescribed increased from 36.8% to 47.0% (P < 0.001). Antibiotic prescribing was highest for sinusitis (adjusted proportion, 86%) and bronchitis (85%) and varied little according to fever, age, setting, or comorbid conditions. Substantial variation was identified in prescribing at the provider level: The 10% of providers who prescribed the most antibiotics did so during at least 95% of their ARI visits, and the 10% who prescribed the least did so during 40% or fewer of their ARI visits. Some clinical data that may have influenced the prescribing decision were missing. Veterans with ARIs commonly receive antibiotics, regardless of patient, provider, or setting characteristics. Macrolide use has increased, and substantial variation was identified in antibiotic prescribing at the provider level. U.S. Department of Veterans Affairs, Centers for Disease Control and Prevention.