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. 2023 Feb 16;11(2):498.
doi: 10.3390/microorganisms11020498.

Legionella pneumophila Infections during a 7-Year Retrospective Analysis (2016-2022): Epidemiological, Clinical Features and Outcomes in Patients with Legionnaires' Disease

Tommaso Lupia  1 , Silvia Corcione  2   3 , Nour Shbaklo  2 , Barbara Rizzello  2 , Ilaria De Benedetto  2 , Erika Concialdi  4 , Anna Sara Navazio  4 , Maurizio Penna  4 , Maria Teresa Brusa  1 , Francesco Giuseppe De Rosa  1   2
Affiliations

Legionella pneumophila Infections during a 7-Year Retrospective Analysis (2016-2022): Epidemiological, Clinical Features and Outcomes in Patients with Legionnaires' Disease

Tommaso Lupia et al. Microorganisms. .

Abstract

Legionella pneumophila (LP) is one of the main causative agents of community-acquired pneumonia in Europe and its fifth bacterial cause in Italy (4.9%). We conducted a seven year retrospective analysis of LP infection serogroup 1 in Asti, Piedmont, between 2016 and 2022. Patients were included if they tested positive for the Legionella urinary antigen. Clinical, laboratory, and radiologic data were analyzed to describe the risk factors for mortality. Fifty patients with LD were collected, mainly male, with a median age of 69 years. The main comorbidities were cardiovascular diseases (50%), pulmonary diseases (26%), and neurological diseases (12%). The most common clinical presentations were fever, respiratory, gastrointestinal, and neurologic symptoms. Older age (p = 0.004), underlying cardiovascular diseases (p = 0.009), late diagnosis at admission (p = 0.035), and neurological symptoms at diagnosis (p = 0.046) were more common in the non-survivor group. Moreover, a septic-shock presentation or the need for non-invasive ventilation at admission were associated with a higher mortality. No considerable differences in the biochemical data were found between the two groups except for the median neutrophil count, lymphocyte count, neutrophil-to-lymphocyte ratio, and PCT value. We did not find any differences in mortality related to the choice of antibiotic regimen. Differences in outcome were associated with the median duration of treatment (p =< 0.001) but not to the choice of antibiotic regimen (mainly levofloxacin or azithromycin). In conclusion, early individuation of the wide spectrum of clinical characteristics of LP infection such as respiratory, cardiac, and neurological manifestations of the patient's comorbidities, and significant biochemical data should help clinicians flag high risk patients and potentially improve their outcome.

Keywords: Legionella; Legionnaires disease; lymphopenia; neutrophil-to-lymphocyte ratio; pneumonia; urinary antigen.

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Conflict of interest statement

The authors declare no conflict of interest for this manuscript.

Figures

Figure 1
Figure 1
The LD rates per 100,000 population in Italy per year, 2016–2020, modified from [6].
Figure 2
Figure 2
Trend of LD toward years of study.
Figure 3
Figure 3
Seasonality of LD.
See this image and copyright information in PMC

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