Symptoms of post COVID-19 condition and diseases/conditions diagnosed after COVID-19 in Japanese patients: A real-world study using a claims database.

BACKGROUND: More than 200 symptoms of post coronavirus disease (COVID-19) condition (PCC) impacting patients' quality of life have been reported. This study describes the symptoms of well-known PCC and diseases/conditions diagnosed after COVID-19 and analyzes the trends in well-known PCC according to the epidemic waves in the Japanese population. METHODS: Patients with a COVID-19 diagnosis in the JMDC claims database were matched 1:1 with individuals without COVID-19 diagnosis (controls) based on sex, year and month of birth, and risk factors for aggravation. The first month of COVID-19 diagnosis from January 2020-March 2022 was the index month, and the observation period was from July 2019 to 6 months from the index month (patients) and July 2019-September 2022 (controls). RESULTS: Of 263,456 each of patients and controls after matching, 51.8 % were aged 18-49 years, 56.3 % were male, and 24.5 % had risk factors for aggravation. One in 18 patients experienced well-known PCC 2-3 months after severe acute respiratory syndrome cornonavirus 2 infection, with the highest odds ratio (OR) being for pulmonary thromboembolism (29.37), followed by smell/taste disorder (13.34) and respiratory failure (8.28). Some of the common diseases/conditions diagnosed after COVID-19 comprised those of the genitourinary system, eye and adnexa, and ear and mastoid process and certain infectious and parasitic diseases. Overall, the risk difference decreased from the first to the sixth wave, but the OR was >1.00 for most symptoms even during the sixth wave. CONCLUSIONS: PCC symptoms showed a declining trend over time but persisted. Physicians and patients need to recognize PCC symptoms.

Successful treatment of Staphylococcus argenteus sequence type 2198 uncomplicated bacteremia with a 2-week antibiotic course.

There is a paucity of data on the clinical course and treatment of Staphylococcus argenteus. Herein, we describe a successfully treated case of S. argenteus bacteremia. A 76-year-old man with lung adenocarcinoma developed bacteremia caused by penicillin-resistant, oxacillin-susceptible S. argenteus, which was identified through mass spectrometry and nuc gene sequencing. He was diagnosed with a peripheral line-associated bloodstream infection and successfully treated with a 2-week course of cefepime, followed by cefazolin, concurrent with intravenous catheter removal. The isolate was positive for blaZ and negative for mecA. It was assigned to sequence type 2198 using multilocus sequence typing. Formerly classified as Staphylococcus aureus clonal complex 75, S. argenteus became a distinct species in 2015. Its identification has increased owing to widespread mass spectrometer use. Most East and Southeast Asian S. argenteus isolates reported to date are methicillin-susceptible, consistent with the susceptibility pattern of the isolate in our study. Given the potential equivalence in virulence between S. argenteus and S. aureus, we recommend treating S. argenteus with the same rigor as S. aureus until further clinical data becomes available.

COVID-19 severity and corticosteroid treatment have minimal effect on specific antibody production.

BACKGROUND: Dexamethasone is currently administered for Coronavirus disease 2019(COVID-19); however, there are concerns about its effect on specific antibodies' production. The aim of this study was to evaluate whether specific antibodies were affected by COVID-19 severity and corticosteroid treatment. METHODS: Of 251 confirmed COVID-19 patients admitted to our hospital between January 26 and August 10, 2020, the early period of the pandemic, 75 patients with sera within 1 month of onset and 1 month or longer were included in the research. A total of 253 serum samples from these patients were collected. The levels of specific antibodies for severe acute respiratory syndrome coronavirus 2(SARS-CoV-2), immunoglobulin G (IgG) and M (IgM), were measured retrospectively. The results were compared separately of each COVID-19 severity, and with or without corticosteroid treatment. RESULTS: Among the 75 patients, 47, 18, and 10 had mild, moderate, and severe disease, respectively. The median age was 53.0 years and 22 (29%) were women. The most common comorbidities were hypertension and dyslipidemia. Corticosteroids were administered to 20 (27%) and 10 (53%), patients with moderate and severe disease, respectively. The positivity rates IgM increased first, and IgG was almost always positive after day 16, regardless of the severity of COVID-19. On days 6-10, both IgG and IgM positivity rates were higher in patients with moderate disease than in those with mild or severe disease. In patients with moderate disease, IgG positivity was similar over time, regardless of corticosteroid treatment. CONCLUSIONS: In COVID-19 patients, specific IgG is positive and maintained for a long period of time, even after corticosteroid treatment. The effect of corticosteroid treatment in a COVID-19 epidemiological study using specific IgG antibodies was considered minor. COVID-19 patients were more likely to receive oxygen if IgM was positive 1 week after onset, but not mechanical ventilation. IgM measurement 1 week after onset may predict COVID-19 severity.

Travel-associated sexually transmitted infections in Japan: An observational study using imported infectious disease registry data.

International travel is a risk factor for acquiring sexually transmitted infections (STIs) owing to factors such as increased sexual opportunities, a sense of freedom, and the allure of the sex industry. We investigated the incidence of travel-associated STIs in Japan using data from the Japan Registry for Infectious Diseases from Abroad (J-RIDA) reported by 17 participating medical institutions between October 2017 and December 2022. Data were collected on the patients' age, sex, nationality, chief complaint, whether they had visited a travel clinic before travel, travel history, and final diagnosis. Of 4545 cases of travel-associated illness reported, 52 (1.1%) were STIs. Most patients with STIs were male (81%) with a median age of 31 years. HIV (17%), genital herpes (13%), syphilis (13%), and gonorrhea (12%) were the most frequently reported STIs. Only one patient had visited a travel clinic before travel. Promoting awareness and vaccination is crucial for preventing travel-associated STIs.

Accuracy of odor-based microorganism identification by microbiological technologists with different years of experience: A cross-sectional study.

Introduction: Elucidating the characteristic odors of microbes can facilitate microorganism identification. This study aimed to evaluate the accuracy of microbial identification based on odor and its association with years of experience among microbiological technologists. Methods: A cross-sectional study was conducted on February 19, 2023, in Osaka, Japan, in a laboratory capable of handling microorganisms that were rated at or below biosafety level 2. This study included 70 microbiological technologists (including 45 women) with a mean experience of 7.1 years (standard deviation, 5.7). Ten bacterial strains with distinct odors were selected. Participants were blindfolded and asked to identify the bacterial strains based on odor of cultured microbes alone. Linear and logistic regression analyses were used for data analysis. The primary outcome was the number of accurately identified bacterial strains per year of experience. Results: The number of years of experience was not significantly associated with the accuracy of odor identification (regression coefficient = 0.037 [95 % confidence interval: 0.038 to 0.113]). Additionally, generally low accuracy was noted in the identification of individual microbial species. Conclusions: Our findings indicate that microorganism identification based solely on odor is challenging. Incorporating additional information, such as visual cues, may enhance the identification accuracy.

First case report of cefmetazole-induced disulfiram-like reaction.

Disulfiram-like reactions occur when alcohol is consumed concurrently with certain drugs and can sometimes be fatal. Some cephalosporins such as cefoperazone could cause disulfiram-like reaction, known as cephalosporin-induced disulfiram-like reactions (CIDLRs). We describe a case of cefmetazole (CMZ)-treated CIDLR triggered by alcohol consumption. A 72-year-old Japanese man, treated with CMZ for perforated appendicitis and subsequent paralytic ileus, presented with skin flushing and chest discomfort, developing 30 min after consuming usual meals and alcohol. CIDLR was diagnosed due to recent use of CMZ and the symptoms alleviated without any medication. This is the first case report of a CMZ-induced disulfiram-like reaction.

Long-acting antiretroviral therapy effectiveness and patient satisfaction using patient questionnaires: data from a real-world setting.

BACKGROUND: Antiretroviral therapy (ART) for HIV infection has evolved substantially. The development of long-acting drugs, such as cabotegravir (CAB) and rilpivirine (RPV) might improve treatment satisfaction among people living with HIV (PLWH). The real-world effectiveness of long-acting ART and its effect on patient satisfaction needs to be assessed. This study investigated antiviral effectiveness and treatment satisfaction in PLWH who switched from conventional to long-acting ART (CAB + RPV). METHODS: This prospective cohort study included PLWH aged 18 years and older who switched to CAB + RPV and received the injections every 8 weeks between June 2022 and May 2023, after a 4-week oral lead-in phase. The eligibility criteria included viral suppression, absence of hepatitis B virus (HBV) DNA, and no prior RPV resistance mutations. Clinical data, including renal, lipid, and glucose biomarker levels, were monitored from the baseline to 44 weeks after switching. Treatment satisfaction was assessed using the HIV Treatment Satisfaction Questionnaire. A linear mixed-effects model was used to estimate changes in clinical data from baseline. RESULTS: Thirty-eight male participants were enrolled. Some participants had detectable levels of viral replication; however, all participants maintained viral suppression (HIV-RNA < 50 copies/mL) at 44 weeks and no cases of virological failure were detected. The creatinine level decreased by - 0.04 mg/dL (95% confidence interval [CI]: - 0.07 to - 0.01), lipid and glucose profiles remained stable, and treatment satisfaction increased by 6.6 points (95% CI: 2.4 to 10.8) after switching to CAB + RPV. CONCLUSIONS: Long-acting ART provides effective viral suppression and enhances treatment satisfaction in PLWH switching from conventional ART. Long-acting ART can improve patient well-being; however, patient selection and monitoring to prevent HBV-related complications are important.

Unexpected Sudden Deaths Following the Co-administration of Ceftriaxone and Lansoprazole: A Case Series.

Ceftriaxone and lansoprazole are commonly used in clinical settings, but recent analyses indicate a potential risk for QTc prolongation and cardiac events when used together. This case series examines three patients from a cohort of sudden death cases at a single institution over a decade, who received both medications within 24 hours before death. Three cases were identified, each with contributing factors for cardiac arrhythmias. The results underscore the importance of monitoring and possibly avoiding this drug combination in patients at risk of QT prolongation, pending further investigation into the underlying mechanisms.

Ruthenibacterium lactatiformans isolated from a human blood culture: a first report.

BACKGROUND: Ruthenibacterium lactatiformans, a Gram-stain-negative, rod-shaped, obligate anaerobic bacterium of the Oscillospiraceae family, has not been previously reported in human infections. This study reports the first case of bacteraemia and potential vertebral osteomyelitis caused by Ruthenibacterium lactatiformans. CASE PRESENTATION: An 82-year-old man with a history of diabetes, chronic renal failure, and prior spinal surgery for spondylolisthesis and spinal stenosis presented with fever and lower back pain. Magnetic resonance imaging revealed multiple vertebral osteomyelitis lesions. Initial blood cultures identified methicillin-resistant Staphylococcus aureus (MRSA), which prompted vancomycin treatment. However, repeated blood cultures not only confirmed persistent MRSA, but also detected Gram-negative bacilli (GNB). Despite surgical removal of the spinal hardware and antimicrobial therapy, the patient's osteomyelitis worsened, necessitating transfer for further management. Subsequent analysis using 16S rRNA gene sequencing identified the GNB as Ruthenibacterium lactatiformans. CONCLUSIONS: This is the first documented instance of human infection with Ruthenibacterium lactatiformans, signifying its pathogenic potential in vertebral osteomyelitis. The involvement of anaerobic bacteria and the possibility of polymicrobial infections complicate the diagnosis and treatment of vertebral osteomyelitis. This report underscores the need for caution when identifying the causative organism and selecting an appropriate treatment.

Exploring the efficacy of routine antimicrobial therapy in severe fever with thrombocytopenia syndrome: Overlap weighting analysis using a nationwide inpatient database.

BACKGROUND: Severe fever with thrombocytopenia syndrome (SFTS) is an infectious disease that presents a formidable challenge due to the absence of established therapeutic strategies that are explicitly tailored to its management. This study aimed to assess the impact of routine antimicrobial therapy on patients diagnosed with SFTS in Japan. We conducted a comprehensive retrospective cohort analysis using extensive data from a national inpatient database. METHODS: This study scrutinized data from adult patients with SFTS and categorized them based on whether they received antimicrobial treatment within the initial 2 days of hospital admission. A meticulous evaluation was carried out on a range of outcomes, such as in-hospital mortality rates, overall costs associated with hospitalization, and length of hospital stay. Overlap weighting was applied along with multivariate regression models to enhance the reliability of the findings through confounder adjustment. The outcomes showed no significant improvement in the prognosis of patients with SFTS who received routine antimicrobial therapy. The use of antimicrobials did not yield statistically significant improvements in in-hospital mortality rates or other secondary outcomes, suggesting that such therapeutic interventions may not be necessary during the early stages of hospital admission. CONCLUSION: In our study, administration of antimicrobials within 2 days of admission for SFTS did not affect prognosis. The standard use of antimicrobial treatments may be an issue that should be reconsidered.

Association between post-COVID-19 conditions and male semen quality in Japan: A descriptive investigation.

Some reports suggest that coronavirus disease 2019 (COVID-19) may affect male reproductive function. There is also concern in Japan that COVID-19 may contribute to the pre-existing decline in male fertility; however, no studies have investigated the effects of COVID-19 on male reproductive function. In this study, we aimed to analyze the semen quality of men who had recovered from COVID-19. Male patients who had recovered from COVID-19 between February 2020 and September 2021 were recruited for this study. Participants were sent a semen collection kit; they were asked to collect semen at home and deliver it to a laboratory at Osaka University. We used these samples to analyze sperm concentration, total sperm count, and semen volume. In total, 125 participants were included in this study. The median age of all patients was 46 years (interquartile range (IQR): 38-52 years). The severity of COVID-19 was mild in 80 patients; 19 were moderate I, 22 were moderate II, and four were severe. The median semen volume was 2.5 mL (IQR: 1.8-3.1), the median sperm concentration was 98.9 million/mL (IQR: 43.8-162.2), and the median total sperm count was 212.1 million (IQR: 89.7-368.2). In a previous study in Japan, the median sperm count in adult men was reported to be 201 million. Participants in our study did not have lower sperm counts than this, despite their older age. Our results suggest that the long-term effects of COVID-19 on spermatogenesis are minimal.

Peritonsillar abscess associated with Helicobacter cinaedi bacteremia: A case report.

Helicobacter cinaedi, a gram-negative spiral bacterium, has historically been associated with infections primarily in immunocompromised patients. Recently, however, its potential to cause infections in immunocompetent individuals has been recognized. We report a unique case of a man in his 20 s who reported having sex with men. He presented with symptoms of fever and throat discomfort and was diagnosed with a peritonsillar abscess. While the rapid antigen test for Group A Streptococcus was positive and antibiotics were administered, a puncture fluid from the peritonsillar abscess taken the day after antibiotic treatment revealed the presence of Group C Streptococcus. By the fifth day, the blood culture taken on the first day detected a gram-negative spirochete, which was subsequently identified H. cinaedi. The patient had engaged in oral sex with his male partner, suggesting a potential transmission route. This is significant as H. cinaedi was initially identified from rectal cultures in men who have sex with men (MSM), raising the possibility of pharyngeal transmission through oral sex. In our patient, although H. cinaedi was not isolated from the aspirate of the peritonsillar abscess, its presence in the blood culture and lack of other potential sources of bacteremia make the abscess a likely primary site of infection. This case highlights the importance of considering H. cinaedi as a potential pathogen in immunocompetent patients, particularly in cases of MSM. The potential for H. cinaedi transmission through oral sex and its role in the development of peritonsillar abscesses, a previously unreported association, requires further investigation.

Oral mouthwashes for asymptomatic to mildly symptomatic adults with COVID-19 and salivary viral load: a randomized, placebo-controlled, open-label clinical trial.

BACKGROUND: Recent randomized clinical trials suggest that the effect of using cetylpyridinium chloride (CPC) mouthwashes on the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral load in COVID-19 patients has been inconsistent. Additionally, no clinical study has investigated the effectiveness of on-demand aqueous chlorine dioxide mouthwash against COVID-19. METHODS: We performed a randomized, placebo-controlled, open-label clinical trial to assess for any effects of using mouthwash on the salivary SARS-CoV-2 viral load among asymptomatic to mildly symptomatic adult COVID-19-positive patients. Patients were randomized to receive either 20 mL of 0.05% CPC, 10 mL of 0.01% on-demand aqueous chlorine dioxide, or 20 mL of placebo mouthwash (purified water) in a 1:1:1 ratio. The primary endpoint was the cycle threshold (Ct) values employed for SARS-CoV-2 salivary viral load estimation. We used linear mixed-effects models to assess for any effect of the mouthwashes on SARS-CoV-2 salivary viral load. RESULTS: Of a total of 96 eligible participants enrolled from November 7, 2022, to January 19, 2023, 90 were accepted for the primary analysis. The use of 0.05% CPC mouthwash was not shown to be superior to placebo in change from baseline salivary Ct value at 30 min (difference vs. placebo, 0.640; 95% confidence interval [CI], -1.425 to 2.706; P = 0.543); 2 h (difference vs. placebo, 1.158; 95% CI, -0.797 to 3.112; P = 0.246); 4 h (difference vs. placebo, 1.283; 95% CI, -0.719 to 3.285; P = 0.209); 10 h (difference vs. placebo, 0.304; 95% CI, -1.777 to 2.385; P = 0.775); or 24 h (difference vs. placebo, 0.782; 95% CI, -1.195 to 2.759; P = 0.438). The use of 0.01% on-demand aqueous chlorine dioxide mouthwash was also not shown to be superior to placebo in change from baseline salivary Ct value at 30 min (difference vs. placebo, 0.905; 95% CI, -1.079 to 2.888; P = 0.371); 2 h (difference vs. placebo, 0.709; 95% CI, -1.275 to 2.693; P = 0.483); 4 h (difference vs. placebo, 0.220; 95% CI, -1.787 to 2.226; P = 0.830); 10 h (difference vs. placebo, 0.198; 95% CI, -1.901 to 2.296; P = 0.854); or 24 h (difference vs. placebo, 0.784; 95% CI, -1.236 to 2.804; P = 0.447). CONCLUSIONS: In asymptomatic to mildly symptomatic adults with COVID-19, compared to placebo, the use of 0.05% CPC and 0.01% on-demand aqueous chlorine dioxide mouthwash did not lead to a significant reduction in SARS-CoV-2 salivary viral load. Future studies of the efficacy of CPC and on-demand aqueous chlorine dioxide mouthwash on the viral viability of SARS-CoV-2 should be conducted using different specimen types and in multiple populations and settings.

Using novel micropore technology combined with artificial intelligence to differentiate Staphylococcus aureus and Staphylococcus epidermidis.

Methods for identifying bacterial pathogens are broadly categorised into conventional culture-based microbiology, nucleic acid-based tests, and mass spectrometry. The conventional method requires several days to isolate and identify bacteria. Nucleic acid-based tests and mass spectrometry are relatively rapid and reliable, but they require trained technicians. Moreover, mass spectrometry requires expensive equipment. The development of a novel, inexpensive, and simple technique for identifying bacterial pathogens is needed. Through combining micropore technology and assembly machine learning, we developed a novel classifier whose receiver operating characteristic (ROC) curve showed an area under the ROC curve of 0.94, which rapidly differentiated between Staphylococcus aureus and Staphylococcus epidermidis in this proof-of-concept study. Morphologically similar bacteria belonging to an identical genus can be distinguished using our method, which requires no specific training, and may facilitate the diagnosis and treatment of patients with bacterial infections in remote areas and in developing countries.

Epidemiology of post-COVID conditions beyond 3 years and factors associated with their persistence longer than 2 years: A cross-sectional study.

OBJECTIVE: This study aimed to investigate the epidemiology of post-coronavirus disease 2019 (COVID-19) conditions (PCCs) beyond 3 years and identify factors associated with their persistence longer than 2 years. STUDY DESIGN: Cross-sectional questionnaire-based survey. METHODS: We surveyed patients who had recovered from COVID-19 and visited our institution from February 2020 to November 2021. Demographic and clinical data and information on the presence and duration of PCCs were obtained. We identified factors associated with the persistence of PCCs longer than 2 years using multivariate linear regression analyses. RESULTS: Among 935 patients surveyed, 407 completed the survey. Among them, 360 patients had mild disease in the acute phase. The proportions of participants with at least one symptom at 1, 2, and 3 years after symptom onset or COVID-19 diagnosis were 33.2%, 29.8%, and 5.7%, respectively. The numbers of participants with and without any residual symptoms 2 years after the onset of COVID-19 were 87 and 193, respectively. After multivariate adjustment, persistence of PCCs longer than 2 years was associated with lower body mass index, presence of any underlying medical conditions, and number of symptoms lasting for more than 1 month ≥ 5. CONCLUSIONS: The prevalence of PCCs decreased 2 years after symptom onset or COVID-19 diagnosis. We also identified factors associated with PCC persistence longer than 2 years, which could help primary care physicians and patients with PCCs predict the duration of PCCs and better understand their natural history, thus reducing patients' anxiety about their duration.

Clostridium butyricum Bacteremia Associated with Probiotic Use, Japan.

Clostridium butyricum, a probiotic commonly prescribed in Asia, most notably as MIYA-BM (Miyarisan Pharmaceutical Co., Ltd.; https://www.miyarisan.com), occasionally leads to bacteremia. The prevalence and characteristics of C. butyricum bacteremia and its bacteriologic and genetic underpinnings remain unknown. We retrospectively investigated patients admitted to Osaka University Hospital during September 2011-February 2023. Whole-genome sequencing revealed 5 (0.08%) cases of C. butyricum bacteremia among 6,576 case-patients who had blood cultures positive for any bacteria. Four patients consumed MIYA-BM, and 1 patient consumed a different C. butyricum-containing probiotic. Most patients had compromised immune systems, and common symptoms included fever and abdominal distress. One patient died of nonocclusive mesenteric ischemia. Sequencing results confirmed that all identified C. butyricum bacteremia strains were probiotic derivatives. Our findings underscore the risk for bacteremia resulting from probiotic use, especially in hospitalized patients, necessitating judicious prescription practices.

Analysis of Differences in Characteristics of High-Risk Endemic Areas for Contracting Japanese Spotted Fever, Tsutsugamushi Disease, and Severe Fever With Thrombocytopenia Syndrome.

Background: Tick-borne infections, including tsutsugamushi disease, Japanese spotted fever, and severe fever with thrombocytopenia syndrome (SFTS), are prevalent in East Asia with varying geographic distribution and seasonality. This study aimed to investigate the differences in the characteristics among endemic areas for contracting each infection. Methods: We conducted an ecologic study in Japan, using data from a nationwide inpatient database and publicly available geospatial data. We identified 4493 patients who were hospitalized for tick-borne infections between July 2010 and March 2021. Mixed-effects modified Poisson regression analysis was used to identify factors associated with a higher risk of contracting each tick-borne disease (Tsutsugamushi, Japanese spotted fever, and SFTS). Results: Mixed-effects modified Poisson regression analysis revealed that environmental factors, such as temperature, sunlight duration, elevation, precipitation, and vegetation, were associated with the risk of contracting these diseases. Tsutsugamushi disease was positively associated with higher temperatures, farms, and forests, whereas Japanese spotted fever and SFTS were positively associated with higher solar radiation and forests. Conclusions: Our findings from this ecologic study indicate that different environmental factors play a significant role in the risk of transmission of tick-borne infections. Understanding the differences can aid in identifying high-risk areas and developing public health strategies for infection prevention. Further research is needed to address causal relationships.

Analysis of the effectiveness of combination antimicrobial therapy for Legionnaires' disease: A nationwide inpatient database study.

OBJECTIVES: The effectiveness of monotherapy and combination therapy with quinolones and macrolides for treating Legionnaires' disease remains uncertain; this study aimed to assess the comparative effectiveness of three treatment approaches. METHODS: Using a nationwide inpatient database, we analyzed 3560 eligible patients hospitalized for Legionnaires' disease between April 1, 2014, and March 31, 2021; patients were divided into combination therapy, quinolone monotherapy, and macrolide monotherapy groups according to the antibiotics administered within 2 days of admission. We compared in-hospital mortality, total hospitalization costs, and length of stay across these groups using multiple propensity score analysis with inverse probability of treatment weighting. RESULTS: Of the 3560 patients, there were 564 (15.8%), 2221 (62.4%), and 775 (21.8%) patients in the combination therapy, quinolone monotherapy, and macrolide monotherapy groups, respectively. No significant differences were observed in in-hospital mortality between combination therapy and quinolone monotherapy groups, and between combination therapy and macrolide monotherapy groups. There were no significant differences in total hospitalization costs or length of stay among the three groups. CONCLUSION: The study suggests that there may not be a significant advantage in using a combination of quinolones and macrolides over monotherapy for the treatment of Legionnaires' disease. Given the potential for increased side effects, careful consideration is advised when choosing this combination therapy.

Epidemiological Analysis of Legionella Pneumonia in Japan: A National Inpatient Database Study.

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 International Classification of Diseases, 10th revision 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 7,370 enrolled hospitalized patients from 1,140 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. CONCLUSION: 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.

Cross-sectional surveillance study of long COVID in Toyonaka city, Osaka prefecture, Japan.

BACKGROUND: As the COVID-19 epidemic continues, concerns about long-term health impacts, specifically long COVID, persist. While the prevalence and symptomatology of long COVID have been explored in various global contexts, large-scale cohort studies in Japan remain limited, especially after the advent of the Omicron variant. METHODS: In this observational study, 4,047 residents with a history of COVID-19 living in Toyonaka City, Osaka Prefecture, were assessed for long COVID symptoms using the VOICE mobile application and a paper survey. Respondents provided demographic and health information, as well as information regarding COVID-19 infection and subsequent symptoms. A Cox proportional hazard regression model was used to estimate the multivariable-adjusted hazard ratios and 95 % confidence intervals for overall morbidity of long COVID symptoms. RESULTS: The survey found that 5.2 % of participants reported the persistence of one or more symptoms at 30 days post-onset. Fatigue was the most commonly reported symptom (1.75 %), followed by hair loss (1.41 %), and cough (1.28 %). Factors associated with an increased risk of experiencing long COVID symptoms included BMI, severe illness during the acute phase, and infection with certain COVID-19 variant strains, including Alpha, Delta, and Omicron. However, the incidence rate of long COVID appears to be decreasing with the dominance of the Omicron variant. CONCLUSIONS: This large-scale study from Toyonaka City suggests a 5.2 % prevalence rate for persistent COVID-19 symptoms 4 weeks post-infection, potentially indicating a lower prevalence of long COVID in Japanese populations after the rise of the Omicron variant.