BACKGROUND: Legionella pneumonia, a severe form of pneumonia, is caused by Legionella bacteria. The epidemiology of Legionnaires\' disease in Japan, including seasonal trends, risk factors for severe disease, and fatality rates, is unclear. This study examined the epidemiology of Legionella pneumonia in Japan.
METHODS: This retrospective cohort study included data of adult patients hospitalized for Legionella pneumonia (identified using the ICD-10 code, A481) in the Japanese Diagnosis Procedure Combination inpatient database, from April 2011 to March 2021. We performed multivariable logistic regression analysis to explore the prognostic factors of in-hospital mortality.
RESULTS: Of 7370 enrolled hospitalized patients from 1140 hospitals (male, 84.4%; aged >50 years, 87.9%), 469 (6.4%) died during hospitalization. The number of hospitalized patients increased yearly, from 658 in 2016 to 975 in 2020. Multivariable logistic regression analysis revealed that higher in-hospital mortality was associated with older age, male sex, lower body mass index, worsened level of consciousness, comorbidities (congestive heart failure, chronic renal diseases, and metastasis), hospitalization from November to May, and ambulance use. However, lower in-hospital mortality was associated with comorbidity (liver diseases), hospitalization after 2013, and hospitalization in hospitals with higher case volume.
CONCLUSIONS: The characterized epidemiology of Legionella pneumonia in Japan revealed a high mortality rate of 6.4%. To the best of our knowledge, this is the first study to demonstrate a higher mortality rate in winter and in patients with congestive heart failure and metastasis. Further research is needed to understand the complex interplay between the prognostic factors of Legionella pneumonia.

The guidelines for the requirement of Legionella urinary antigen tests on admission for patients hospitalized with community-acquired pneumonia differ in Japan, the United States, and Europe. We aimed to evaluate the association between the timing of Legionella urinary antigen testing and inhospital mortality in patients with atypical pneumonia.
We identified 654,708 patients with atypical pneumonia from July 2010 to March 2021 using the Japanese national inpatient database. The patients were divided into groups that underwent Legionella urinary antigen tests on the day of admission (test group, n = 229,649) and those that underwent testing after the day of admission or were untested (control group, n = 425,059). A propensity score-stabilized inverse probability of treatment weighting analysis was performed to compare inhospital mortality, length of hospital stay, and total hospitalization costs between the two groups. Odds ratios (ORs) or differences and their 95% confidence intervals (CIs) were calculated using generalized linear models.
The tested group had a significantly lower 30-day inhospital mortality than that of the control group (7.7% vs. 9.0%; OR: 0.83 [95% CIs, 0.81-0.86]). The tested group also had a significantly shorter length of stay (difference, -2.3 [-2.6 to - 2.0] days and total hospitalization costs (-396 [-508 to - 285] US dollars) than that of the control group.
Legionella urinary antigen testing upon admission is associated with better outcomes in patients with atypical pneumonia. Legionella urinary antigen testing performed on the day of admission is recommended for hospitalized patients with atypical pneumonia.

Objective Recommendations on the timing of Legionella urinary antigen tests for community-acquired pneumonia patients differ among guidelines in Japan, the United States, and European nations. We therefore evaluated the association between the timing of urinary antigen tests and in-hospital mortality in patients with Legionella pneumonia. Methods We conducted a retrospective cohort study using the Diagnosis Procedure Combination database, a nationwide database of acute care inpatients in Japan. Patients who underwent Legionella urinary antigen tests on the day of admission formed the tested group. Patients who were tested on day 2 of admission or later or were unexamined formed the control group. We performed a propensity score matching analysis to compare in-hospital mortality, length of hospital stay and duration of antibiotics use between the two groups. Results Of the 9,254 eligible patients, 6,933 were included in the tested group. One-to-one propensity score matching generated 1,945 pairs. The tested group had a significantly lower 30-day in-hospital mortality than the control group (5.7 vs. 7.7%; odds ratio, 0.72; 95% confidence intervals, 0.55-0.95; p=0.020). The tested group also showed a significantly shorter length of stay and duration of antibiotics use than the control group. Conclusion Urine antigen testing upon admission was associated with better outcomes in patients with Legionella pneumonia. Urine antigen tests upon admission may be recommended for all patients with severe community-acquired pneumonia.

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.

UNASSIGNED: In real-life practice, only 20% of hospitalised pneumonia cases have an identified etiology. The usage of Legionella urine antigen test (LUAT) in developed nations revolutionised case detection rates. Accordingly, our objectives were to study the microbiological etiology for hospitalised pneumonia patients and the diagnosis of Legionella pneumonia.
UNASSIGNED: A prospective, observational single-centre study was conducted where all 504 cases that were consecutively admitted for pneumonia were enrolled. Blood and sputum samples obtained were used to identify pathogens using standard microbiological culture methods. The urine samples collected were tested using the ImmunocatchTM Legionella immunochromatographic (ICT) urine antigen test.
UNASSIGNED: A microbiological diagnosis was only achieved in 104 cases (20.6%) and a Gram-negative infection predominance was observed. Culture-positive cases required longer hospitalisation (8.46 days versus 5.53 days; P < 0.001) and the higher usage of antipseudomonal antibiotics (23.1% versus 8.3%; P < 0.001). Only 3 cases (0.6%) were diagnosed with Legionella pneumonia.
UNASSIGNED: The local pathogen distribution is diverse compared to other regions. Culture-negative pneumonia is common and significantly differs from culture-positive pneumonia. Legionella pneumophila serotype 1 is not a common cause of pneumonia and LUAT did not help demystify the cause of culture-negative pneumonia.

Idiopathic spontaneous hemothorax has been rarely described in the literature.
A case of status asthmaticus and spontaneous hemothorax is described in a 29-year-old female of African descent who presented to the emergency room after 2 days of severe cough productive of yellow sputum, otalgia, sore throat, subjective fevers, chills, headache, progressive wheezing, chest tightness and dyspnea. She had a history of 7 years of asthma and was non-adherent with her controller asthma medications. Prophylactic subcutaneous administration of enoxaparin 40 milligrams was initiated upon hospitalization. The patient initially had a normal chest radiograph but subsequently developed a large, left hemothorax that required tube thoracostomy placement followed by video-assisted thoracoscopic surgery (VATS).
The patient was transferred to the Intensive Care Unit (ICU) and tube thoracostomy resulted in evacuation of 1,400 milliliters of blood-like fluid, which had a pleural fluid hematocrit greater than 50% of the serum hematocrit. A contrast-enhanced computed tomography (CT) scan of the chest did not reveal any source for the bleeding and a technetium bone scan of the chest was normal. The patient required transfusion of 5 units of packed red blood cells. She was then taken to the operating room for VATS because of continued chest tube drainage (3,200 milliliters of fluid over a 48-hour period).
The etiology of the hemothorax was unknown despite surgical exploration but was felt to be secondary to cough and bronchospasm associated with status asthmaticus.