Japanese journal of infectious diseases最新文献

Recently, Staphylococcus argenteus, previously indistinguishable from Staphylococcus aureus, has been recognized as a clinically relevant microorganism because of mass spectrometry. However, despite its clinical significance, limited information is available on S. argenteus. This study evaluated the antimicrobial susceptibility and clinical phenotypes of S. argenteus isolated from clinical specimens. This single-center, retrospective study analyzed cases wherein S. argenteus was detected in clinical specimens obtained at Nagoya City University East Medical Center between April 2023 and April 2024. The organism was identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. Patient data, including clinical outcomes, were collected and reviewed to classify cases as infections or colonization. S. argenteus was isolated from 23 specimens of 21 patients, with sputum being the most common source (78.3%). Sixty-seven percent of isolates were susceptible to penicillin; 95.2% to erythromycin; and 100% to oxacillin, clindamycin, sulfamethoxazole-trimethoprim, vancomycin, and teicoplanin. Thirteen cases of infection were recorded; pneumonia was the predominant diagnosis (11 cases) in these cases, followed by otitis externa and vertebral osteomyelitis. Most patients were successfully treated with antibiotics, and only one died of S. argenteus pneumonia.

Epidemics of respiratory syncytial virus (RSV) infection used to follow predictable and seasonal pattern. However, the emergence of COVID-19 and the accompanying public health measures disrupted the RSV seasonality worldwide. To investigate the long-term epidemiological impact, we analyzed weekly RSV-related hospitalizations in children under 15 years of age from 2018 to 2024 in Saitama Prefecture, Japan. During the COVID-19 pandemic, RSV admissions notably declined in 2020, but the number of hospitalizations returned to pre-pandemic levels. The peaks of admission rates occurred in March, in both 2023 and 2024, which were earlier than the August peaks seen in 2018 and 2019. We also found the proportion of hospitalized patients aged ≥2 years increased notably to 30% in 2021 and 2022, and declined to 21.2% in 2024. Although an upward trend in intubation rates was observed, no statistically significant differences were found. These findings suggest that the COVID-19 pandemic led to earlier RSV outbreaks and temporary shifts in age distribution. It remains unclear whether RSV seasonality and age patterns will return to their pre-pandemic status. Ongoing surveillance is essential to better predict future outbreaks and inform optimal timing for preventive interventions such as vaccination or monoclonal antibody administration.

Cyclospora cayetanensis, a food and waterborne pathogen, is responsible for prolonged diarrheal illness. This study aimed to investigate the prevalence, risk factors and seasonal patterns of C. cayetanensis infection among diarrheic patients in eastern India. A hospital-based cross-sectional study was conducted. The overall prevalence of C. cayetanensis in the study region was determined to be 2.11%. The highest incidence (7%) was observed during the monsoon months, particularly in July and August. Children aged >5-12years were the most susceptible group (17.8%,OR=47.45,P<0.0001). Individuals from households lacking proper sanitation or from rural areas showed higher burden of infection. Statistically significant association between infection and contact with animals was also found (3.45%; OR=2.81; P<0.0001). Symptomatic individuals predominantly experienced profuse diarrhea with abdominal cramps. Coinfections with Soil Transmitted Helminths (STHs) was found to be most common in Cyclospora positive cases. Limited genetic diversity of Cyclospora was found within the population, with 6 haplotypes circulating in the region. Overall, this study highlights the public health risk posed by C. cayetanensis in eastern India. We recommend including Cyclospora detection in routine laboratory diagnoses to prevent its spread. Raising awareness regarding hygiene and implementing rigorous control measures will prove effective in eradication of Cyclospora from this endemic country.

Staphylococcus argenteus is a novel bacterial species distinct from Staphylococcus aureus. Nevertheless, S. argenteus is often misidentified as S. aureus because they cannot be differentiated easily using routine diagnostic microbiology methods. An 81-year-old man was admitted because of persistent lumbar pain and fever. Strains from his blood cultures were initially identified as methicillin-susceptible S. aureus. Enhanced computed tomography revealed an erector spinae abscess connected with the L5 transverse process, and magnetic resonance imaging of the lumbar region showed a high intensity of L1 and L5 on short tau inversion recovery. The abovementioned pathogen was also cultured from the aspiration fluid of the abscess. Therefore, the patient was diagnosed with vertebral osteomyelitis with an erector spinae abscess. We analyzed the detected strain using matrix-assisted laser desorption ionization time-of-flight mass spectrometry and whole-genome sequencing, re-identifying the strain as S. argenteus sequence type (ST)1223. Although S. argenteus ST1223 has mainly enteric pathogenicity, our case suggests its potential to invade the musculoskeletal system. Its pathogenicity was similar to or greater than that of S. aureus in both previous studies and our case. Thus, the clinical differentiation of S. argenteus and S. aureus warrants further investigation.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has repeatedly undergone mutations since its emergence, based on which, it has been assumed that there have been changes in its characteristics, including virulence and antigenicity. In this study, the viral loads in nasopharyngeal samples of patients with SARS-CoV-2 in Gunma Prefecture, Japan, from April 2, 2020, to April 1, 2023, were determined. The number of virus in samples in the Omicron-variant-prevalent period was higher than that in strains detected in samples before Week 50 of 2020; the B.1.1.284-prevalent period, the Alpha-variant-prevalent period, and the Delta-variant-prevalent period. Moreover, among the Omicron variants, the sub-lineage BA.5-prevalent period had more viral copies in the samples than in the BA.1-prevalent and BA.2-prevalent periods. Hence, the new variant may have released more viruses into the nasopharynx during the process of repeated mutations, resulting in widespread infection. The number of viruses detected in the nasopharyngeal samples showed an increasing trend with the evolution of the virus. Therefore, considering that the number of viruses in samples is also a vital factor contributing to the spread of the infection, it is important to determine the viral load in samples.

MinION sequencing is widely used to sequence influenza A virus (IAV) genomes. However, the accuracy and utility of this approach, which uses the latest chemistry to obtain whole viral genome sequences directly from clinical samples, remain insufficiently investigated. We evaluated the sequencing accuracy of combining simultaneous multi-segment one-step RT-PCR and MinION sequencing using various subtypes of 13 IAV isolates. The latest R10.4.1 chemistry significantly improved sequencing accuracy, achieving ≥99.993% identity with the results of Illumina MiSeq and reducing single nucleotide deletion in homopolymer regions. Applying this method to 11 clinical samples enabled rapid subtype identification and acquisition of eight full-length IAV genomes. In four of these samples, subtype identification of hemagglutinin and neuraminidase was achieved within 20 min of starting the sequencing, and a full-length IAV genome was obtained within 7 h of RNA extraction. However, cross-barcode misassignment during demultiplexing might have affected data interpretation, particularly for samples with low viral genome copy numbers. Although careful data analysis is required for multiplex sequencing of clinical samples with low viral genome copy numbers, this approach can be used for the rapid identification of IAV subtypes and accurate acquisition of full IAV genome sequences from clinical samples.

A measles outbreak occurred in Japan in February 2024 due to a measles virus variant imported from central Asian countries with three mismatches at the PCR reverse primer (MVN1213R) annealing site. To examine and improve the effectiveness of real-time PCR for detecting this variant, we compared the sensitivity of real-time PCR for MVN1213R and a modified primer using control RNAs, clinical isolates, and clinical specimens. The median difference in the cycle threshold value using the modified primer was 2.92 cycles lower (interquartile range, 1.99-3.38) than when using MVN1213R. Thus, PCR primer sets should be modified to effectively detect measles virus mutations.

Early and accurate diagnosis of leprosy is important but remains a significant challenge. Loop-mediated isothermal amplification (LAMP) is a process for the amplification of nucleic acids at a constant temperature and has been used to develop field-friendly tests for many diseases. In the present study, we describe the development of a colorimetric LAMP assay targeting Mycobacterium leprae-specific 450 bp conserved region of the repeat sequences known as RLEP. In addition, the amplicons of LAMP were subjected to restriction analysis using the enzyme EcoRV for specificity. This method has the potential to become an accurate and efficient alternative to Sanger sequencing, which is currently used to validate RLEP-amplified products.

We describe six independent cases of Mesocestoides infection in dogs presenting with diarrhea. Between November 2022 and August 2024, we were contacted by veterinarians regarding the identification of a species of small tapeworm excreted in dog feces. The veterinarians suspected the organism was Echinococcus multilocularis and believed it should be reported to health centers as a notifiable disease. Segmented and unsegmented worms, approximately 600 to 1,400 µm in length, were recovered from fecal samples. Microscopically, the worms had four suckers on the scolex but no rostellum. Subsequent molecular analysis of the mitochondrial cox1 and 12S rDNA genes revealed that all cases involved Mesocestoides vogae. The affected dogs were treated with an anthelmintic, and the diarrhea disappeared immediately. Possibly owing to the heavy infection load, the host animals had developed diarrhea, with the parasite likely expelled before reaching maturity. These small tapeworms with few proglottids could, therefore, confuse veterinarians.

This study aimed to characterize cardiac injury in individuals diagnosed with severe fever with thrombocytopenia syndrome (SFTS) and to ascertain its relationship with prognosis. A retrospective analysis of data from 324 patients, diagnosed with SFTS between January 2021 and December 2023, was performed. Patients were categorized into survival and non-survival groups. Univariate and multivariate analyses were performed to identify significant indicators and predictive risk factors for mortality. Statistically significant differences in various parameters were found between the 2 groups, including age, history of hypertension, presence of diarrhea, petechiae, neurological abnormalities, and numerous laboratory measurements. These included lymphocyte, monocyte, and platelet counts, as well as liver enzyme levels, kidney function markers, cardiac biomarkers, clotting factors, inflammatory markers, Dabie Banda virus RNA, heart rate, PR interval, QT interval, and incidence of ST depression. Age, history of hypertension, neurological abnormalities, and creatinine, prothrombin time, and QT intervals were independent risk factors for mortality. The incidence of viral myocarditis in patients with SFTS was 64.12%, and the non-survival group demonstrated a higher incidence of cardiac injury, both earlier and more severe. The incidence of viral myocarditis in patients with SFTS was closely associated with prognosis.