Gotway, Michael B

An accurate differential diagnosis for diffuse lung disease can be confidently established by using a systematic approach to identify the predominant radiographic pattern, determine the distribution of disease, and assess for architectural or volume change.

Abstract Rationale Legionella species can cause severe community-acquired pneumonia requiring targeted antimicrobial therapy. The impact of time to effective Legionella-directed therapy on mortality is not well defined. Objectives To evaluate the association between time to effective Legionella-directed therapy and mortality in hospitalized patients with community-acquired Legionella pneumonia and to determine whether differences in treatment timing contribute to the excess mortality observed among immunocompromised patients. Methods A retrospective multicenter cohort study of adults hospitalized with laboratory-confirmed community-acquired Legionella pneumonia (2019–2025) was performed. Time from presentation to effective therapy (macrolide, fluoroquinolone, or doxycycline) was recorded. The primary outcome was 90-day mortality. Multivariable logistic regression analysis was performed, adjusting for age, SOFA-2 score (first 6 hours), and immunocompromised status. Secondary analyses included a 24-hour landmark Cox model for 90-day survival and multivariable logistic regression for 30-day mortality. Results Among 310 patients (median age 66.9 years, 44.8% immunocompromised), 90-day mortality was 17.4%. Every 6-hour delay in effective therapy was independently associated with increased 90-day mortality (adjusted OR per 6 hours: 1.11; 95% CI, 1.06–1.17; P < 0.001). Delays >24 hours were associated with worse 90-day survival (adjusted HR, 2.72; 95% CI, 1.65–4.77; P < 0.001). Time to effective therapy was also independently associated with increased odds of 30 day mortality (adjusted OR per 6 hours: 1.06; 95% CI: 1.01-1.11, p = 0.024). Immunocompromised patients experienced longer delays (median, 7.1 versus 3.3 hours; P < 0.001) and higher unadjusted 90-day mortality (22.3% versus 13.5%; P = 0.041), but immunocompromised status was not independently associated with mortality after adjusting for severity and treatment timing. Conclusion Longer time to effective Legionella-directed therapy was independently associated with increased mortality in a graded fashion. Delays were more common among immunocompromised patients, partially accounting for excess mortality in this group, suggesting that timely pathogen-directed therapy may represent a clinically important and potentially modifiable contributor to risk.

In a large, multicenter cohort of HIV and non–HIV immunocompromised patients with Pneumocystis jirovecii pneumonia, chest CT most commonly demonstrated diffusely distributed ground-glass opacity, with no imaging features distinguishing between immunocompromise etiology.

This article describes the typical and atypical chest imaging appearances of Pneumocystis jirovecii pneumonia.

Abstract Background Legionella pneumonia is an important cause of severe pneumonia, yet contemporary data describing its clinical phenotype, diagnostic patterns, and outcomes in the modern era are limited. Methods We conducted a retrospective multicenter cohort study of adults with laboratory-confirmed Legionella pneumonia across an integrated health system between January 2019 and September 2025. The primary outcome was 30-day mortality. Severe disease was defined as having a requirement for high-flow nasal cannula, noninvasive ventilation, mechanical ventilation, or extracorporeal membrane oxygenation (ECMO). Univariate and multivariable logistic regression were used to identify predictors of mortality and severe disease. Results There were 344 patients with laboratory-confirmed Legionella pneumonia during the study period. The median age was 66.6 years, and 45.1% were immunocompromised. Most patients required hospital admission (94.2%), with 36.1% admitted to the intensive care unit; 22.7% required mechanical ventilation and 1.5% ECMO. Thirty- and 90-day mortality were 11.9% and 16.6%, respectively. In multivariable analysis, cirrhosis (OR 10.2, 95% CI 2.15–48.3, P = .003), immunocompromised status (odds ratio [OR] 2.24, 95% CI 1.05–4.77, P = .036), age (OR 1.03, 95% CI 1.00–1.06, P = .031), and lymphopenia at presentation (OR 2.09, 95% CI 1.02–4.24, P = .043) were independently associated with increased 30-day mortality. Among patients who were polymerase chain reaction (PCR) or culture positive, urinary antigen testing was positive in only 25.6%. Conclusions Legionella pneumonia was associated with substantial short-term mortality. Cirrhosis, age, immunocompromised status, and lymphopenia at presentation emerged as independent predictors of 30-day mortality, underscoring the importance of host vulnerability in determining outcomes.

This essay describes diagnostic criteria for and thoracic imaging appearances of acute and chronic coccidioidal pneumonia, unusual disease manifestations, and disseminated disease appearances.

Pneumocystis pneumonia (PCP) is a serious fungal infection affecting immunocompromised hosts. Decompensated cirrhosis leads to cirrhosis-associated immune dysfunction (CAID), a form of impaired cellular immunity that may predispose patients to opportunistic infections such as PCP. We conducted a retrospective review of 727 patients with proven or probable PCP from 2017 to 2025. Of these, 33 had decompensated cirrhosis. These patients were stratified into two groups: Cirrhosis Only (n = 16) and Cirrhosis with Additional Immunocompromising Conditions (n = 17). Among the patients with cirrhosis, the overall mortality was 48%, with the 90-day mortality reaching 57.6% (95% CI: 39.2–74.5%). Compared with those without cirrhosis, the patients with cirrhosis had a higher risk of mortality (OR: 4.08, 95% CI: 2.01–8.30, p < 0.001), increased intensive care unit (ICU) admission (87% vs. 42%, p < 0.001), and greater need for renal replacement therapy (54.6% vs. 7.5%, p < 0.001). These findings suggest that decompensated cirrhosis alone may represent a sufficient and underrecognized risk factor for PCP, with a high associated mortality. Given the preventable nature of this infection, future studies are needed to assess the incidence, define the risk, and investigate the role of prophylaxis in this vulnerable population.

Abstract Background Pneumocystis jirovecii pneumonia (PCP) is increasingly seen in patients who are non-HIV immunocompromised hosts, yet modern risk factors and outcomes are poorly recognized and defined. Methods A retrospective review was conducted of adult patients who met criteria for proven or probable PCP from 2017 to 2024 across a large academic multicenter health system. The primary outcome was mortality among cohorts, defined by etiology of immunosuppression through univariate and age-adjusted logistic regression. Secondary analyses included trends in annual diagnoses and testing patterns. Results A total of 701 patients met criteria for inclusion, representing one of the largest clinically characterized cohorts of PCP to date. The median age was 65 years (IQR, 54–73) and 62% were male. The most common risk groups were hematologic malignancy (32.2%), solid tumor cancers receiving chemotherapy (22.4%), and autoimmune disease with immunosuppression (17.7%). Annual PCP diagnoses increased at a rate of 15.8% (95% CI, 8.9%–23.2%) in parallel with increased testing. Only 5.4% of patients were receiving prophylaxis at the time of diagnosis. Overall mortality was 20% (95% CI, 17%–23%) and highest in cirrhosis (adjusted odds ratio, 6.24; 95% CI, 2.84–13.69; P &lt; .001). Conclusions PCP in the current era affects a broad range of patients who are immunocompromised, with high associated mortality and low rates of prophylaxis. Patients with solid tumors and those with cirrhosis are at particularly high risk of mortality. These findings highlight the need to reassess and redefine PCP prophylaxis guidelines in specific populations and our understanding of who is at risk.