The number of reported cases of Legionnaires\' disease (LD) has risen markedly in Switzerland (6.5/100,000 inhabitants in 2021) and abroad over the last decade. Legionella, the causative agent of LD, are ubiquitous in the environment. Therefore, environmental changes can affect the incidence of LD, for example by increasing bacterial concentrations in the environment or by facilitating transmission.
The aim of this study is to understand the environmental determinants, in particular weather conditions, for the regional and seasonal distribution of LD in Switzerland.
We conducted a series of analyses based on the Swiss LD notification data from 2017 to 2021. First, we used a descriptive and hotspot analysis to map LD cases and identify regional clusters. Second, we applied an ecological model to identify environmental determinants on case frequency at the district level. Third, we applied a case-crossover design using distributed lag non-linear models to identify short-term associations between seven weather variables and LD occurrence. Lastly, we performed a sensitivity analysis for the case-crossover design including NO2 levels available for the year 2019.
Canton Ticino in southern Switzerland was identified as a hotspot in the cluster analysis, with a standardised notification rate of 14.3 cases/100,000 inhabitants (CI: 12.6, 16.0). The strongest association with LD frequency in the ecological model was found for large-scale factors such as weather and air pollution. The case-crossover study confirmed the strong association of elevated daily mean temperature (OR 2.83; CI: 1.70, 4.70) and mean daily vapour pressure (OR: 1.52, CI: 1.15, 2.01) 6-14 days before LD occurrence.
Our analyses showed an influence of weather with a specific temporal pattern before the onset of LD, which may provide insights into the effect mechanism. The relationship between air pollution and LD and the interplay with weather should be further investigated.

Extrapulmonary manifestations of infection with Legionella species, of which 24 may cause disease in humans, are very rare. Here, we describe a case of a 61-year-old woman with no history of immunosuppression presenting with pain and swelling of her index finger after a prick by rose thorns during gardening. Clinical examination showed fusiform swelling of the finger with mild redness, warmth, and fever. The blood sample revealed a normal white blood cell count and a slight increase in C-reactive protein. Intraoperative observation showed extensive infectious destruction of the tendon sheath, while the flexor tendons were spared. Conventional cultures were negative, while 16S rRNA PCR analysis identified Legionella longbeachae that also could be isolated on buffered charcoal yeast extract media. The patient was treated with oral levofloxacin for 13 days, and the infection healed quickly. The present case report, with a review of the literature, indicates that Legionella species wound infections may be underdiagnosed due to the requirement for specific media and diagnostic methods. It emphasizes the need for heightened awareness of these infections during history taking and clinical examination of patients presenting with cutaneous infections.

A 69-year-old male with a history of prior admissions of heat exhaustion presented with non-specific symptoms including fatigue, diarrhea, and dehydration. The workup revealed a positive legionella urine antigen. He was treated with levofloxacin with symptom resolution within 48 hours.

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Cognitive biases, such as the availability heuristic or availability bias, can inadvertently affect patient outcomes. These biases may be magnified during times of heightened awareness of a particular disease. Failure to identify cognitive biases when managing patients during the coronavirus disease 2019 (COVID-19) pandemic can delay the institution of the right treatment option and result in poor health outcomes. We present a case of delayed diagnosis of Legionella pneumonia due to COVID-19-related availability bias. We discuss some methods to mitigate the effects of this bias and the importance of challenging trainees to recognize these pitfalls in medical training.

BACKGROUND: The goal of the study was to analyze the clinical characteristics of Legionella cases caused by Legionella micdadei and explore the diagnosis and treatment.
METHODS: The pathogen was identified by routine isolation and culture, biochemical identification, serum agglutination test, mass spectrometry identification, and routine PCR. Combined with the related literature review, the clinical diagnosis and treatment of Legionella micdadei were analyzed.
RESULTS: The patient suffered from pulmonary infection caused by Legionella micdadei. After treatment with moxi-floxacin for 2 weeks, the body temperature dropped and the shadow of the lung was completely absorbed after 2 months. Combined with literature analysis, 8 cases of Legionella micetidis, including 7 males and 1 female, aged from 27 to 57 years old, 6 cases with basic diseases, which were treated with azithromycin, erythromycin or levofloxacin, and all of them achieved good therapeutic effect.
CONCLUSIONS: The detection of Legionella should be strengthened in patients with pneumonia whose symptoms have no obvious improvement after antibiotic treatment. Azithromycin, erythromycin or levofloxacin are effective in the treatment of Legionella spp.
BACKGROUND:

As a type of Legionella bacteria, Legionella longbeachae bacteria can lead to very rare legionella disease case in China with clinical characteristics, such as no typical early clinical symptoms, strong toxicity, high mortality, and not easy to detect by conventional etiology. A case of severe pneumonia caused by Legionella longbeachae infection was confirmed by bronchoalveolar lavage fluid pathogen metagenomics, and the patient\'s condition was improved after targeted anti-infection treatment. At present, our understanding in Legionella longbeachae severe pneumonia is limited. The diagnosis and treatment process of the patient with severe pneumonia of Legionella longbeachaeis retrospectively analyzed and the relevant literature was reviewed to provide the experience for its future diagnosis and treatment.
长滩军团菌作为军团菌的一种，其导致的军团菌病在国内十分罕见，且患者早期临床症状不典型、毒力强、致死率高，常规病原学检测不易检出。通过支气管肺泡灌洗液病原宏基因组学确诊了1例长滩军团菌感染所致的重症肺炎患者，在针对性抗感染治疗后患者病情好转。目前对长滩军团菌性肺炎认识有限，本文通过回顾性分析1例收治的长滩军团菌性重症肺炎患者的诊断、治疗过程，并对相关文献进行复习，可对其以后的诊断、治疗提供经验。.

Legionella longbeachae pneumonia is much less common than Legionella pneumophila pneumonia in most of the world and may evade timely diagnosis in settings that rely primarily on urine antigen testing, which detects Legionella pnuemophila serogroup 1 only. It is, however, widely recognized in Australia and New Zealand, where it is endemic and associated with exposure to compost and potting soils, rather than contaminated water systems as seen with L. pneumophila. L. longbeachae can cause a similar spectrum and severity of illness as L. pneumophila. Here we present a case of a 47-year-old man with L. longbeacheae necrotizing pneumonia following exposure to possibly contaminated soil from a wastewater treatment facility. Initial presentation included cough, chest pain, and dyspnea, and progressed to hypoxic respiratory failure, tension pneumothorax, and cardiac arrest. L. pneumophila urine antigen was negative, but bronchioalveolar lavage samples grew L. longbeachae on buffered charcoal yeast extract agar. A review of cases reported in the literature in non-endemic regions over a 20-year period identified 38 cases in Europe, 33 in Asia, and 8 in North America. Average age was 65, 65 % were male, and 35 % had potentially relevant environmental exposures. L. longbeachae should be considered in cases of severe community acquired pneumonia, particularly following a consistent environmental exposure or if initial testing for other pathogens is unrevealing. A thorough exposure history including questions about contact with potting soil or compost, and utilization of specialized agar for culture can both be key in identifying this pathogen.

Herein, we report the case of a 74-year-old man diagnosed with Legionella pneumonia detected by Loop-Mediated Isothermal Amplification (LAMP) method, which was suspected to have been transmitted from the potting soil. Legionella longbeachae was identified in the sputum culture. The patient was intubated and maintained on mechanical ventilation. Antimicrobial therapy with azithromycin was also administered. His symptoms were resolved and he was discharged after 26 days of hospitalization. Legionella longbeachae pneumonia rarely occurs in Japan, and published literature of Legionella longbeachae pneumonia cases in Japan was reviewed. Patients with severe pneumonia exposed to potting soils, but with negative urinary antigen test results, should be examined by LAMP method.

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