Japanese journal of infectious diseases最新文献

Escherichia coli O157 and O26 are well-known Shiga toxin-producing E. coli (STEC) serotypes, but other serotypes such as O91, O103, O111, O121, O145, and O165 have also emerged as important public health concerns. PCR-based methods, such as multilocus variable-number tandem-repeat analysis (MLVA), are commonly used for rapid genotyping of STEC strains. However, MLVA requires analysis of numerous loci, some of which are serotype-specific, limiting its applicability across multiple STEC serotypes. In this study, we developed a PCR-based open reading frame typing (POT) method for genotyping diverse STEC serotypes. By detecting 22 ORFs using two multiplex PCR assays, STEC genotypes were determined based on the presence or absence of specific ORFs. Most STEC serotypes, except for O121, were classified with high discriminatory power (Simpson's index: 0.95-0.98). STEC-POT represents a rapid, cost-effective, and broadly applicable molecular typing tool. It facilitates timely outbreak detection and enhances public health surveillance by enabling rapid molecular epidemiological investigations.

We investigated the association between frequenting 3Cs (closed spaces, crowded places, and close-contact settings) and trust in information on COVID-19, to elucidate information sources affecting public preventive measures. Nonprobability quota sampling was used to recruit 2000 residents of Tokyo and 2000 from Osaka. The retrospective survey was conducted in April 2024. These participants responded to an online survey about two periods, with and without an emergency declaration. Multiple regression analyses were performed and standardized partial regression coefficients for the independent variables calculated. Without an emergency declaration, a negative association between frequenting 3Cs and trust in family/relatives and a positive association with daily conversation were observed. 3Cs anxiety was positively associated with trust in three sources: medical professionals, family/relatives, or television (TV). During the emergency declaration period, a negative association between frequenting 3Cs and trust and a positive association between 3Cs anxiety and trust in the three sources above were observed, while there was a positive association between frequenting 3Cs and trust in celebrities, weekly magazines, or social networking services. A mediation analysis showed that trust in medical professionals, family/relatives, or TV increased 3Cs anxiety, and frequenting 3Cs decreased in state of emergency situations.

Urban wastewater is increasingly recognized as a major reservoir of antimicrobial resistance and horizontal gene transfer. From urban wastewater in Hanoi, Vietnam, we isolated a multidrug-resistant Pseudomonas guariconensis strain, KNHN1, resistant to most antimicrobials, including carbapenems and cephalosporins, but susceptible to cefiderocol; and intermediate to colistin. Whole-genome sequencing revealed two chromosomally integrated integrative and conjugative elements (ICEs): ICE_{PgKNHN1_KPC} (131 kb) carrying bla_KPC-2 and ICE_{PgKNHN1_NDM} (108 kb), carrying bla_NDM-1, both flanked by conserved 18-bp att sites in the tRNA^Gly loci and encoding MOB_H-type relaxases. Polymerase chain reaction and subsequent sequencing confirmed ICE excision from the chromosome and formation of circular intermediates. Conjugation to Pseudomonas putida KT2440 occurred at ~10⁻² frequency, producing transconjugants with ICE_{PgKNHN1_NDM} (~85%), ICE_{PgKNHN1_KPC} (~10%), or both, all showing broad range β-lactam resistance. Comparative analysis indicated that ICE_{PgKNHN1_NDM} has a highly conserved backbone across multiple species and often co-carries bla_PME-1 and other resistance genes. To our knowledge, this is the first report of chromosomally integrated bla_NDM‑1 and bla_KPC‑2 in P. guariconensis mediated by functional ICEs. These findings underscore the pivotal role of environmental bacteria as reservoirs of clinically significant resistance genes, and highlight ICEs as key drivers in the dissemination of carbapenem resistance.

Early detection of leprosy is crucial since delayed treatment can result in deformities and impairments. Recombinase Polymerase Amplification (RPA) is an isothermal DNA amplification technique that amplifies DNA fragments at a single, moderate temperature using a mixture of recombinase enzymes. In this work, PCR-confirmed cases of leprosy (positive for Mycobacterium leprae DNA) were subjected to RPA targeting an in-house designed RLEP amplicon of 175 bp. Following amplification, the RPA amplicons were analysed using agarose gel electrophoresis and SYBR Green I. The RPA-based detection of M. leprae DNA can be achieved within 20 min at 39 °C. The analytical sensitivity of the test was 0.5 cells/µl when tested using purified M. leprae genomic DNA standards. The clinical performance of the RPA was evaluated using 28 DNA samples extracted from skin biopsies. This assay has greater potential for developing a quick, accessible and field-friendly method for the visual detection of M. leprae DNA.

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.

The aim of this study was to determine the prevalence and persistence of extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) carriage among hospital food handlers. A prospective, single-center study was conducted in Sagamihara, Japan, from July to December 2021. Residual fecal specimens from routine examinations of 119 hospital food handlers were analyzed for ESBL-E and carbapenem-resistant Enterobacteriaceae (CRE). ESBL-E were detected in 32 isolates from 11 participants (9.2%), with Escherichia coli as the predominant species and a mean monthly positivity rate of 4.48%. The frequency of ESBL-E carriage was higher in individuals younger than 40 years of age (17.5%) than in those aged 40 years or above (5.1%). Highly homologous strains were detected within and between participants; the most common resistance genes were bla_CTX-M-1 group and bla_CTX-M-9 group. Six participants showed persistent ESBL-E carriage but CRE was not detected. These findings suggest that ESBL-E carriage is common among hospital food handlers, particularly among younger individuals, highlighting the need for enhanced surveillance and targeted hygiene interventions to limit ESBL-E transmission in healthcare food services.

This large-scale post-marketing surveillance study (163 sites; February 2022-May 2023) evaluated the real-world safety and effectiveness of a newly initiated nirmatrelvir plus ritonavir combination for patients with COVID-19 in Japan. The current study reports the safety evaluation. The observation period was 28 days after the last day of administration. The safety analysis set comprised 2829 patients (mean [standard deviation] age, 63.1 [18.0] years; mild COVID-19, 80.8%; ≥1 risk factor for progression to severe COVID-19, 97.3%). The most common reason for discontinuing follow-up was symptom improvement (17.1%). Adverse drug reactions (ADRs) were observed in 423 (15.0%) patients (incidence [%]): dysgeusia (6.7%), diarrhea (2.6%), taste disturbance (1.5%), nausea (1.2%), vomiting (0.5%), decreased appetite (0.5%), and rash (0.5%). The median times to onset and recovery of these ADRs were 1-2 days and 2-6 days, respectively. Serious ADRs were observed in 6 patients (0.2%). No new safety signals were observed. The study showed that nirmatrelvir plus ritonavir was well tolerated in Japanese patients with COVID-19 in a real-world clinical setting. ClinicalTrials.gov number: NCT05263908.

Cefiderocol (CFDC) is a novel siderophore cephalosporin with a unique cell entry feature and a high stability against a wide range of β-lactamases. We conducted antimicrobial susceptibility testing on 89 clinical isolates of carbapenem-non-susceptible gram-negative bacilli (CNS-GNB) strains detected at our hospital, evaluating the efficacy of novel antibiotics including CFDC, ceftolozane/tazobactam, ceftazidime/avibactam, and imipenem/cilastatin/relebactam. The strains included were as follows, 21 carbapenemase-producing Enterobacterales (CPE), 40 carbapenem-resistant Pseudomonas aeruginosa (CRPA), and 28 Stenotrophomonas maltophilia. Carbapenemase production were detected using NG-Test^® CARBA 5. Carbapenemase genes were analyzed by PCR-sequencing and extended-spectrum β-lactamase (ESBL) genes were detected by PCR. CPE isolates produced 17 IMP-, 3 NDM-, and one KPC-type carbapenemases, and 12 out of 21 CPE isolates produced ESBLs. All 40 CRPA did not produce carbapenemases. All 21 CPE isolates and 95% of CRPA were susceptible to CFDC. Colistin were intermediate against all CPE and 92.5% of CRPA isolates. In S. maltophilia isolates, susceptibility to CFDC and trimethoprim-sulfamethoxazole were 100% and 89.3 %. Although non-susceptibility to CFDC appeared in 2 CRPA isolates, MIC₉₀ of CFDC was within susceptible range against all three groups of clinical isolates. CFDC showed significant promise as a treatment option for infections caused by CNS-GNB.

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 recognised 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 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% CI: 0.88-1.0) indicated very good agreement, supporting NeoDX Dengue Virus Screening Real-Time PCR as a reliable assay for early DENV detection.

The potencies of domestic influenza virus reference antigens were initially calibrated with a single radial immunodiffusion (SRID) assay using primarily prepared international reference antigens. The SRID potency should not be affected when using another reference antigen calibrated with the same international antigen. However, the SRID potency of test antigens can vary, although the causes of these discrepancies remain unclear. Here, we calibrated two candidate reference antigens (Lot A and Lot B) in the A(H3N2) subtype with various pairs of reference reagent sets (antigen and antiserum). The potencies of Lot A and Lot B varied depending on the reagent pair used, with a more pronounced effect in Lot A (CV = 5.4% vs. 3.8%). To explore the cause of these divergences, we analyzed the dissociation constant of each reagent pair and scored them based on the hypothesis that pairs exhibiting stronger antigen-antibody binding would have smaller precipitin rings. Comparing these scores with the respective potency scores, we observed a strong correlation between the Binding score (relative BLI-K_D) and potency score in Lot A (r = 0.8464, p = 0.0001) but not in Lot B (r = 0.4000, p = 0.1408). These data suggest that antigen-antibody binding strength is an influencing factor of SRID potency.