Community-Acquired Legionella pneumophila Pneumonia: A Case-Control Study in Adult Inpatients from 2019 to 2024
Bibliographic record
Abstract
Background: Legionella pneumophila is frequently acquired in the community and generally linked to contaminated domestic hot water systems, hotels, or other environmental sources or of unknown origin. L. pneumophila is a leading cause of pneumonia, especially in high-risk patients such as those over 50 who are immunocompromised or people with pre-existing illnesses. This study examines the factors linked to L. pneumophila acquired in the community in adult patients with hospitalization due to pneumonitis. Methods: This case-control study included 140 hospitalized adult patients admitted to the University Hospital Paolo Giaccone of Palermo between January 2019 and December 2024. Demographic, laboratory, clinical, and microbiological data were collected electronically. Urinary antigen testing and the BioFire FilmArray Pneumonia Panel were used to detect L. pneumophila and were performed within 48 h upon admission. Results: Of 140 pneumonia patients, 70 were positive (SG) and 70 were negative (CG) for L. pneumophila. Comorbidities were significantly associated with the presence of L. pneumophila (p = 0.0046). The most frequent comorbidity was only heart failure (p < 0.0015) and, similarly, for smoke (p = 0.0487). There was no difference in mortality between the two groups (SG). Levofloxacin was the most frequent therapy used in SG (p < 0.0001). Additionally, SG showed significantly lower blood sodium, phosphate, and platelet levels (all p < 0.0001) compared to the CG. In contrast, blood parameters such as LDH, CRP, AST, and ALT were significantly higher (all p < 0.0001). Conclusions: Our research highlights the critical need for early detection of L. pneumophila infections, especially in patients with high CRP levels, moderate hypophosphatemia, or heart failure. In these patients with L. pneumophila, early treatment with macrolide and fluoroquinolone is mandatory to reduce mortality.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".