This study estimated the incidence of extraintestinal pathogenic Escherichia coli (E. coli; ExPEC) infections at Kyushu University Hospital from 2013 to 2018, analyzing 63,041 inpatients and 178,690 outpatients aged ≥20 years. ExPEC infections were defined as E. coli detection in sterile specimens or urine specimens (≥10³ CFU/mL) with increased Sequential Organ Failure Assessment (SOFA) scores or urological infection diagnosis codes. The incidence rate was substantially higher in hospitalized patients (1,209.3 per 100,000 person-years) compared to outpatients (94.5 per 100,000 person-years), with females showing slightly higher rates in both groups. Age was a significant risk factor, with incidence rates increasing markedly in patients aged ≥60 years (inpatients: 1,431.6; outpatients: 125.3 per 100,000 person-years). Importantly, the study revealed that relying solely on diagnostic names underestimated the true number of ExPEC infection cases. The precision rate, defined as the proportion of cases (n = 61) with both E. coli isolated and clinical inflammatory symptoms who received an infectious disease diagnosis (n = 46), was at most 75% for female outpatients. These findings suggest that comprehensive microbiological data combined with clinical criteria provide more accurate surveillance. These findings establish baseline incidence rates for ExPEC infections in a Japanese hospital setting and highlight the clinical significance of these infections, particularly in elderly hospitalized patients.

Group A Streptococcus (GAS) is a major pathogen of respiratory infections in children. This study investigated recent trends in antimicrobial susceptibility among GAS isolates in our hospital and compared them with past data. Between 2021 and 2023, 195 GAS isolates were obtained from 195 pediatric patients. Minimum inhibitory concentrations (MICs) of 22 antimicrobial agents were determined using the broth microdilution method. Susceptibility was categorized as susceptible (S), intermediate (I), or resistant (R) according to the Clinical and Laboratory Standards Institute criteria and compared with six previous surveys (1996–2018; total 1,871 isolates). The number of isolates was low in 2021–2022 but increased sharply in 2023 (n = 157). Most isolates were from throat swabs, and the median age was 5 years (range: 1–15 years). Resistance (I + R) rates were as follows: azithromycin (20%), erythromycin (19%), clarithromycin (19%), tetracycline (8%), and clindamycin (4%). Erythromycin resistance increased from 9% in 1996 to 58% in 2013 but declined to 19% in this study. No β-lactam resistance was previously observed; however, two isolates (1%) showed elevated MICs to cefalexin, suggesting reduced susceptibility. These findings underscore the importance of continued monitoring of GAS isolation trends and antimicrobial resistance, including emerging β-lactam reduced susceptibility.

The Coronavirus disease 2019 (COVID-19) pandemic has disproportionately affected vulnerable populations in long-term care hospitals (LTCHs). This study examines the interplay between patient and hospital factors in relation to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and COVID-19 mortality in Korean LTCHs. This retrospective cohort study included 262,221 patients (aged ≥60) who were hospitalized for >30 days in 2021. Multilevel logistic regression models were used to assess the association of hospital and patient factors with SARS-CoV-2 infection and COVID-19 mortality. At the hospital level, a higher number of doctors was associated with a decreased risk of SARS-CoV-2 infection (odds ratio [OR] = 0.84, 95% confidence interval [CI]: 0.73–0.98) and COVID-19 mortality (OR = 0.85, 95% CI: 0.78–0.93), whereas nurses and nurse aides were associated with an increased risk of SARS-CoV-2 infection (OR = 1.02, 95% CI: 1.00–1.03) and COVID-19 mortality (OR = 1.01, 95% CI: 1.00–1.02). Among patient-level factors, female sex (infection OR = 0.89, 95% CI: 0.83–0.96; mortality OR = 0.65, 95% CI: 0.55–0.77) was associated with decreased risks of both infection and mortality. These findings highlight the importance of staffing and infection control measures to mitigate COVID-19 risk in LTCH settings.

The human bocavirus (HBoV) in children has been identified with an acute lower respiratory tract disease (LRTD). Its prevalence, clinical characteristics, and function as an RTD causal agent are unclear. This study sought to evaluate the laboratory and clinical data of HBoV patients, pinpoint the clinical characteristics linked to HBoV, and examine the distinctions between detecting HBoV alone and in combination with other agents. We used molecular testing to confirm the presence of HBoV DNA and 20 other respiratory pathogens in 1,739 nasopharyngeal samples from hospitalized children at the Pediatric Infectious Diseases Service. 73 children, whose median age was 15 months, had HBoV. Concomitant infection of Bocavirus with another virus was observed in 41 (56.1%) of the patients. Co-infections were observed most frequently with rhinovirus (n = 17) and respiratory syncytial virus (n = 10). There was no difference between the isolated bocavirus and co-infection groups in terms of age, clinical presentations, chest X-ray findings, or laboratory results. The role of HBoV in RTD is supported by the fact that the majority of patients were admitted to the hospital with a diagnosis of pneumonia or bronchopneumonia. HBoV mainly affects the respiratory tract, but it can also cause different clinical manifestations.

This study investigated the etiology of hand, foot, and mouth disease (HFMD) in Yunnan Province, China, in 2023 by sequencing the complete VP1 region of enteroviruses. A total of 185 enteroviruses were identified from 429 stool samples collected from nine prefectures/cities in Yunnan Province in 2023. These findings revealed that CVA16 was the most prevalent serotype, followed by CVA4, CVA6, CVA10, and EV-A71. Phylogenetic analysis revealed that among the 76 CVA16 strains, 73 strains belonged to subgenotype B1a and 3 strains belonged to B1b. Among the 32 CVA4 strains, 31 strains belonged to subgenotype C2, and only 1 strain was C5. All 25 CVA6 strains belonged to subgenotype D3a, all 22 CVA10 strains belonged to genotype C, and all 11 EV-A71 strains belonged to the C4a subgenotype. HFMD genotypes and subgenotype distributions are crucial for public surveillance and outbreak response, and can inform vaccine development.

Dengue virus (DENV), a mosquito-borne flavivirus, has emerged as a major global public health concern, with outbreaks occurring with increasing frequency worldwide, including in India. Laboratory confirmation is essential for accurate diagnosis, effective clinical management, and timely public health response. Real-time PCR (RT-PCR) is recognized as a sensitive and specific method for early diagnosis. This study evaluated the performance of the NeoDX Dengue Virus Screening Real-Time PCR Kit (NeoDX, Bengaluru, India), a pan-DENV assay, against the Centers for Disease Control and Prevention (CDC) DENV-1-4 RT-PCR assay. RNA extracted from 51 sera, obtained from suspected dengue cases, was tested by both assays. Of the 51 samples, 23 were positive by the CDC assay (DENV-1: 6, DENV-2: 4, DENV-3: 10, DEN-4: 3). The NeoDX Dengue Virus Screening Real-Time PCR detected 24 positive samples, including all 23 positive samples by CDC assay, yielding a sensitivity of 100% and specificity of 96.4%. The kappa value (0.961; 95% confidence interval: 0.88–1.0) indicated very good agreement, supporting NeoDX Dengue Virus Screening Real-Time PCR as a reliable assay for early DENV detection.

During the COVID-19 pandemic, Mycoplasma pneumoniae infections were rarely observed in Japan, but a significant outbreak occurred in 2024. At Oita Children’s Hospital, a rapid quenching probe polymerase chain reaction (QP-PCR) method was employed to detect the pathogen and to determine the prevalence of macrolide resistance. Between April 1 and September 30, 2024, we tested 679 patients — 462 (68.0%) were positive and 399 (86.4%) were macrolide resistant. The resistance rate was among the highest reported in Japan and comparable to those in neighboring Asian countries. Inpatients were younger than outpatients, and their diagnoses required longer periods of time; corticosteroids were used in 86% of hospitalized cases. QP-PCR detects common A2063G and A2064G mutations and provides results within 40 minutes, which could promote timely therapy, and this is true particularly in the case of younger children, whose options could be limited. Early administration of effective antimicrobial agents is crucial for the control of macrolide-resistant M. pneumoniae. These findings indicate that QP-PCR-based diagnostics could significantly contribute to the management and control of M. pneumoniae outbreaks.

COVID-19 mortality seems to be higher in high-income, hygienic countries, but this is contrary to conventional communicable diseases, which usually occur in low-income countries. Another characteristic of COVID-19 is that a proportion of infected individuals had no symptoms but transmitted the virus to others. In this paper, the author proposes a hypothesis that infected but asymptomatic individuals produce two kinds of infectious respiratory particles by speaking: large droplets and small aerosols. The large droplets are produced from the saliva by pronouncing a plosive, /p/ or /t/, whereas the small aerosols are produced from the laryngeal secretion by the vibration of vocal cords during the voicing of vowels. The heavy droplets collide with other people’s faces in conversation, resulting in droplet infection. In contrast, the lighter aerosols float in the air, accumulate inside a non-ventilated room after prolonged conversation, and cause airborne infection in other people in the same room. Then, the author discusses the global epidemiology of COVID-19, which may have depended on 1) climate and housing structure, 2) cultural behaviors, and 3) languages among different countries.