Japanese journal of infectious diseases最新文献

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.

An ongoing pertussis epidemic in Okinawa has resulted in 227 reported cases since November 2024. Between December 2024 and February 2025, clinical specimens were collected from 31 cases. We isolated 18 macrolide-resistant Bordetella pertussis (MRBP) strains, all harboring the A2047G mutation in the 23S rRNA gene, confirmed by real-time PCR. Genomic analysis was performed on two MRBP isolated in November 2024 and the 18 MRBP from the current survey. All MRBP in Okinawa formed genetically related clusters with the ptxP3 allele in China (P745) and France (FR7302). However, MRBP strains from Okinawa were divided into three clusters, each with at least eight SNPs between them, and distinct from P745 and FR7302, suggesting the multi-source dissemination of ptxP3 MRBP in Okinawa.

This study investigated the diagnostic accuracy of the quantitative polymerase chain reaction (qPCR) DNA assay in urine and saliva samples, as well as its concordance with serum CMV IgM/IgG testing in infants suspected of congenital cytomegalovirus (cCMV) infection. Furthermore, the study sought to elucidate the correlation between various diagnostic parameters in suspected cases of congenital CMV. A cross-sectional analysis was conducted on newborns suspected of having cCMV infection at RSSA Malang. CMV serology, complete blood count, and qPCR of urine and saliva samples were collected. Statistical analysis was performed on these data with a p-value < 0.05. A significant difference in urine PCR CT value distinguished positive from negative CMV IgM serology groups. A strong correlation (r = 0.728, p < 0.001) and high agreement (κ = 0.693, p < 0.001) between urine and saliva PCR testing suggested saliva as a reliable and non-invasive alternative for newborn screening. The findings of this study underscore the necessity of a comprehensive screening protocol for cCMV, particularly considering the high seroprevalence of CMV in the Indonesian population.

The potency of diphtheria toxoid is determined by titrating neutralizing antibody levels in immunized mice using the Vero cell assay. The WHO manual recommends titration by determining the cytotoxic endpoint through measuring cell metabolism and observing cell morphology under a microscope, which has been conducted in our laboratory; however, the former is time-consuming and the latter subjective. To address these limitations, we have developed a novel endpoint determination method based on cell image analysis. We assessed the feasibility of this image analysis and compared it with microscopic observation and cell metabolism measurement. Consequently, image analysis proved effective for endpoint determination, yielding potency values comparable to existing methods in measuring potencies of commercial vaccines. These findings suggest that image analysis, being objective and convenient, can serve as a reliable alternative method for potency testing of diphtheria vaccines.