Patel, Robin

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.

Abstract Background Identification of the microorganisms causing infection in children with central nervous system infection is important. Conventional cerebrospinal fluid (CSF) tests may provide limited pathogen detection. CSF metagenomic next-generation sequencing (mNGS) may provide broader pathogen detection in a single assay. Methods Results of CSF mNGS testing performed at Mayo Clinic on patients and nonpatients between January 2024 and June 2025 were retrospectively analyzed. The subcohort of children treated at Mayo Clinic was analyzed to assess test performance as compared with conventional CSF diagnostics and potential clinical impact. Results In total 134 patients (138 CSF mNGS tests) from 22 US states and 2 international sites were included. Overall positivity was 16% with viruses representing most (59%) detections. In the Mayo Clinic subcohort (n = 15), test positivity was 27%: organisms included single detections of Streptococcus mitis group and HIV type 1, as well as 2 detections of Epstein-Barr virus, all confirmed by conventional tests. Positive results were associated with CSF pleocytosis (P = .026). Higher yield was observed in participants whose care was overseen by pediatric infectious diseases (PID) specialists (P = .026) and when a specimen hold strategy was applied (P = .033). Most results (87%) did not alter antimicrobial therapy, with 2 negative results contributing to antimicrobial de-escalation. Conclusions CSF mNGS demonstrated higher diagnostic yield in patients whose specimens showed CSF pleocytosis and in those who had PID consultation. Diagnostic stewardship strategies were applied, including specimen hold approaches and PID consultation.

Abstract Background New insights into community-acquired pleural infection microbiology may enable development of more rapid and accessible diagnostics that can streamline treatment. This study systematically compared molecular approaches for pathogen detection in pleural fluid from patients with such infections. Considering the need for rapid results with minimum hands-on time and test complexity, off-label use of the cassette-based, random-access BIOFIRE Joint Infection Panel (BF-JIP, bioMérieux) with and without supplementary in-house polymerase chain reaction (PCR) assays was evaluated. Methods Pleural fluids from 162 subjects from the Mayo Clinic (Rochester, Minnesota) and Haukeland University Hospital (Bergen, Norway), where molecular tests are routinely used for analyzing pleural fluid, were studied. The performance of the BF-JIP was compared to 16S rRNA gene PCR followed by Sanger and/or next-generation sequencing (16S rRNA gene PCR/sequencing), an in-house PCR panel specifically designed for pleural space infections, and culture. Results The BF-JIP supplemented with 3 in-house PCR assays targeting Fusobacterium nucleatum group, Streptococcus intermedius/constellatus, and Aggregatibacter aphrophilus detected 96.8% of pleural infections, providing complete microbial profiles in 70.1%. In comparison, the detection rate of 16S rRNA gene PCR/sequencing was 92.2%, providing complete microbial profiles in 87.0%. Culture detected bacteria in only 31.9% of pleural fluids, providing complete microbial profiles in 15.3%. Conclusions These results underscore the importance of molecular approaches in diagnosing pleural space infections and demonstrate the feasibility of panel-based PCR-based diagnostics for these sometimes-complex infections. The BF-JIP, designed for testing synovial fluid, could be modified to provide a useful diagnostic for testing pleural fluid.

Abstract Background Streptococcus agalactiae (group B Streptococcus [GBS]) may cause pneumonia or may colonize the respiratory tract, making its clinical significance uncertain when detected in respiratory specimens. This study aimed to assess whether clinicians interpreted GBS detected by the BIOFIRE Pneumonia Panel (BF-PP) as a pathogen implicated in pneumonia. Methods This retrospective cohort study included adult patients hospitalized with suspected pneumonia at Mayo Clinic, Rochester, between September 2020 and February 2025. Cases were independently classified into pathogen and nonpathogen groups by 2 infectious diseases (ID) specialists, with a third reviewer resolving disagreements. Clinical characteristics and outcomes of both groups were recorded. A subgroup analysis of patients who had an ID consultation was performed. Results A total of 109 cases were included. GBS was considered a pneumonia pathogen in 47.7% of cases and a nonpathogen in 52.3%. ID consultation was performed in 33.0% of cases, with GBS considered a pathogen in 30.6% of those. Common comorbid conditions included pulmonary, gastrointestinal, neurologic, and cardiovascular disease and obesity. Rates of endotracheal intubation were similar in the pathogen and nonpathogen groups (51.9% vs 50.9%, respectively), with the in-hospital mortality rate being numerically but not significantly higher in the former versus the latter (21.2% vs 14.0%; P = .33); findings were similar in the ID-assessed subgroup. In 76.1% of GBS detections, other microorganisms—most commonly Staphylococcus aureus—were codetected. Only 10.2% of BF-PP GBS-positive specimens were culture positive for GBS. Conclusions While GBS is not an uncommon pneumonia pathogen, the clinical significance of its detection by BF-PP is uncertain in many cases.