Genomic characterization of carbapenemase-producing Enterobacterales from Dhaka food markets unveils the spread of high-risk antimicrobial-resistant clones and plasmids co-carrying bla NDM and mcr-1.1.

Background: The transmission of carbapenemase-producing Enterobacterales (CPE) in the external environment, especially through food, presents a significant public health risk. Objectives: To investigate the prevalence and genetic characteristics of CPE in food markets of Dhaka, Bangladesh, using WGS. Methods: CPE isolates were obtained from different food and water samples collected from food markets in the southern part of Dhaka, Bangladesh. The isolates subsequently underwent molecular typing, WGS employing both short- and long-read sequencers, and plasmid analysis. Results: This study unveiled an extensive spread of CPE, with no significant difference in contamination rates observed in samples (N = 136), including meat (n = 8), fish (n = 5), vegetables (n = 36) or various food-washed water (n = 65) from markets near hospitals or residential areas. Thirty-eight Enterobacterales from 33 samples carried carbapenemase genes (bla NDM-1, -4, -7, bla KPC-2, bla OXA-181 or bla IMI-1). Among these, the high-risk Escherichia coli ST410 clone was the most prevalent and distributed across various locations. Furthermore, the identification of IncHI2 plasmids co-harbouring resistance genes like bla NDM-5 and mcr-1.1, without discernible epidemiological connections, is a unique finding, suggesting their widespread dissemination. Conclusions: The analysis unveils a dynamic landscape of CPE dissemination in food markets, underscored by the proliferation of novel IncHI2 hybrid plasmids carrying both colistin- and carbapenem-resistance genes. This illuminates the ever-evolving landscape of antimicrobial resistance in Dhaka, urging us to confront its emergent challenges.

Emerging Meningococcal B Meningitis in Japan: A Case Report of a 50-Year-Old Japanese Man with Diabetes.

BACKGROUND Meningococcal meningitis is rare in Japan; however, when outbreaks do occur, they predominantly involve domestically infected cases rather than those contracted overseas. CASE REPORT A Japanese man with diabetes in his 50s experienced fever and loss of consciousness, with no history of international travel. In our hospital, gram-negative diplococci were detected in the cerebrospinal fluid (CSF) of the patient by Gram staining, although the rapid agglutination test and cultures of blood and CSF were negative. Multiplex polymerase-chain reaction (PCR) testing returned positive results for meningococcus and parechovirus. Brain MRI revealed a finding of meningitis, but there were no indications of encephalitis. To determine the serotype and genotype, we sent the sample to the National Institute of Infectious Diseases, which identified the serogroup and sequence type (ST) as type B and 2057, respectively. Despite the unknown antimicrobial susceptibility, the patient responded well to empirical treatment with ceftriaxone at 2 g every 12 h, and was discharged with remaining symptoms of dizziness, headache, difficulty hearing in the left ear, and tinnitus in the left ear. CONCLUSIONS In Japan, vaccines covering serogroups A, C, and W/Y are available but not routinely administered. According to epidemiological surveillance reports, serogroup B is the second most common cause of meningococcal meningitis in Japan, yet there is no corresponding vaccine available in the country. This case has prompted a review of the epidemiology of meningococcus in Japan, encompassing strategies for vaccination and hospital infection control to prevent droplet transmission, which includes post-exposure prophylaxis when no prior measures have been implemented.

Genomic analysis of carbapenem- and colistin-resistant Klebsiella pneumoniae complex harbouring mcr-8 and mcr-9 from individuals in Thailand.

The surge in mobile colistin-resistant genes (mcr) has become an increasing public health concern, especially in carbapenem-resistant Enterobacterales (CRE). Prospective surveillance was conducted to explore the genomic characteristics of clinical CRE isolates harbouring mcr in 2015-2020. In this study, we aimed to examine the genomic characteristics and phonotypes of mcr-8 and mcr-9 harbouring carbapenem-resistant K. pneumoniae complex (CRKpnC). Polymerase chain reaction test and genome analysis identified CRKpnC strain AMR20201034 as K. pneumoniae (CRKP) ST147 and strain AMR20200784 as K. quasipneumoniae (CRKQ) ST476, harbouring mcr-8 and mcr-9, respectively. CRKQ exhibited substitutions in chromosomal-mediated colistin resistance genes (pmrB, pmrC, ramA, and lpxM), while CRKP showed two substitutions in crrB, pmrB, pmrC, lpxM and lapB. Both species showed resistance to colistin, with minimal inhibitory concentrations of 8 µg/ml for mcr-8-carrying CRKP isolate and 32 µg/ml for mcr-9-carrying CRKQ isolate. In addition, CRKP harbouring mcr-8 carried blaNDM, while CRKQ harbouring mcr-9 carried blaIMP, conferring carbapenem resistance. Analysis of plasmid replicon types carrying mcr-8 and mcr-9 showed FIA-FII (96,575 bp) and FIB-HI1B (287,118 bp), respectively. In contrast with the plasmid carrying the carbapenemase genes, the CRKQ carried blaIMP-14 on an IncC plasmid, while the CRKP harboured blaNDM-1 on an FIB plasmid. This finding provides a comprehensive insight into another mcr-carrying CRE from patients in Thailand. The other antimicrobial-resistant genes in the CRKP were blaCTX-M-15, blaSHV-11, blaOXA-1, aac(6')-Ib-cr, aph(3')-VI, ARR-3, qnrS1, oqxA, oqxB, sul1, catB3, fosA, and qacE, while those detected in CRKQ were blaOKP-B-15, qnrA1, oqxA, oqxB, sul1, fosA, and qacE. This observation highlights the importance of strengthening official active surveillance efforts to detect, control, and prevent mcr-harbouring CRE and the need for rational drug use in all sectors.

Individual Atg8 paralogs exhibit unique properties in streptococcus pneumoniae-induced hierarchical autophagy.

Individual Atg8 (autophagy related 8) paralogs, comprising MAP1LC3A/LC3A, LC3B, LC3C, GABARAP, GABARAPL1 and GABARAPL2/GATE16, play a crucial role in canonical macroautophagy/autophagy. However, their functions remain unclear owing to functional redundancy. In a previous study, we reported that intracellular Streptococcus pneumoniae triggers hierarchical autophagy in response to bacterial infection. This process commences with the induction of conjugation of Atg8 paralogs (Atg8s) to single membranes (CASM), followed by CASM shedding and subsequent induction of xenophagy. In our recent study, we performed functional analysis of Atg8s during pneumococci-induced hierarchical autophagy. Our findings suggest that LC3A and GABARAPL1 are crucial for CASM induction, whereas GABARAPL2 and GABARAP play sequential roles in CASM shedding and subsequent induction of xenophagy, respectively.Abbreviation: Atg8: autophagy related 8; Atg8s: Atg8 paralogs; CASM: conjugation of Atg8s to single membranes; mpi: minutes post-infection; mpi: minutes post-infection; PcAV: pneumococci-containing autophagic vesicles; PcLV: LC3-associated phagosome (LAPosome)-like vacuole; PcV: pneumococci-containing vesicles; Sp: S. pneumoniae.

Colistin Resistance Mediated by Mcr-3-Related Phosphoethanolamine Transferase Genes in Aeromonas Species Isolated from Aquatic Environments in Avaga and Pakro Communities in the Eastern Region of Ghana.

Purpose: Colistin is classified by the World Health Organization (WHO) as a critically important and last-resort antibiotic for the treatment of infections caused by carbapenem-resistant bacteria. However, colistin resistance mediated by chromosomal mutations or plasmid-linked mobilized colistin resistance (mcr) genes has emerged. Methods: Thirteen mcr-positive Aeromonas species isolated from water samples collected in Eastern Ghana were analyzed using whole-genome sequencing (WGS). Antimicrobial susceptibility was tested using the broth microdilution method. Resistome analysis was performed in silico using a web-based platform. Results: The minimum inhibitory concentration (MIC) of colistin for all except three isolates was >4 µg/mL. Nine new sequence types were identified and whole-genome analysis revealed that the isolates harbored genes (mcr-3-related genes) that code for Lipid A phosphoethanolamine transferases on their chromosomes. BLAST analysis indicated that the amino acid sequences of the mcr-3-related genes detected varied from those previously reported and shared 79.04-99.86% nucleotide sequence identity with publicly available mcr-3 variants and mcr-3-related phosphoethanolamine transferases. Analysis of the genetic context of mcr-3-related genes revealed that the genetic environment surrounding mcr-3-related genes was diverse among the different species of Aeromonas but conserved among isolates of the same species. Mcr-3-related-gene-IS-mcr-3-related-gene segment was identified in three Aeromonas caviae strains. Conclusion: The presence of mcr-3-related genes close to insertion elements is important for continuous monitoring to better understand how to control the mobilization and dissemination of antibiotic resistance genes.

An enterococcal phage-derived enzyme suppresses graft-versus-host disease.

Changes in the gut microbiome have pivotal roles in the pathogenesis of acute graft-versus-host disease (aGVHD) after allogenic haematopoietic cell transplantation (allo-HCT)1-6. However, effective methods for safely resolving gut dysbiosis have not yet been established. An expansion of the pathogen Enterococcus faecalis in the intestine, associated with dysbiosis, has been shown to be a risk factor for aGVHD7-10. Here we analyse the intestinal microbiome of patients with allo-HCT, and find that E. faecalis escapes elimination and proliferates in the intestine by forming biofilms, rather than by acquiring drug-resistance genes. We isolated cytolysin-positive highly pathogenic E. faecalis from faecal samples and identified an anti-E. faecalis enzyme derived from E. faecalis-specific bacteriophages by analysing bacterial whole-genome sequencing data. The antibacterial enzyme had lytic activity against the biofilm of E. faecalis in vitro and in vivo. Furthermore, in aGVHD-induced gnotobiotic mice that were colonized with E. faecalis or with patient faecal samples characterized by the domination of Enterococcus, levels of intestinal cytolysin-positive E. faecalis were decreased and survival was significantly increased in the group that was treated with the E. faecalis-specific enzyme, compared with controls. Thus, administration of a phage-derived antibacterial enzyme that is specific to biofilm-forming pathogenic E. faecalis-which is difficult to eliminate with existing antibiotics-might provide an approach to protect against aGVHD.

Identification and characterization of a novel α-haemolytic streptococci, Streptococcus parapneumoniae sp. nov., which caused bacteremia with pyelonephritis.

OBJECTIVES: We report a case of bacteremia with pyelonephritis in an adult male with an underlying disease caused by α-hemolytic streptococci. α-Hemolytic streptococci were isolated from blood, but it was challenging to identify its species. This study aimed to characterize the causative bacterium SP4011 and to elucidate its species. METHODS: The whole-genome sequence and biochemical characteristics of SP4011 were determined. Based on the genome sequence, phylogenetic analysis was performed with standard strains of each species of α-hemolytic streptococci. Digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values were calculated. RESULTS: SP4011 showed optochin susceptibility and bile solubility, but did not react with pneumococcal omni antiserum. Phylogenetic analysis of the whole-genome sequence showed that SP4011 clustered with S. pneumoniae and S. pseodopneumoniae and was most closely related to S. pseodopneumoniae. Genomic analysis revealed that ANI and dDDH values between SP4011 and S. pseodopneumoniae were 94.0 % and 56.0 %, respectively, and between SP4011 and S. pneumoniae were 93.3 % and 52.2 %, respectively. Biochemical characteristics also showed differences between SP4011 and S. pseodopneumoniae and between SP4011 and S. pneumoniae. These results indicate that SP4011 is a novel species. CONCLUSION: Our findings indicate that SP4011 is a novel species of the genus Streptococcus. SP4011 has biochemical characteristics similar to S. pneumoniae, making it challenging to differentiate and requiring careful clinical diagnosis. This isolate was proposed to be a novel species, Streptococcus parapneumoniae sp. nov. The strain type is SP4011T (= JCM 36068T = KCTC 21228T).

Bacteriological and Serological Investigation of Leptospirosis in Dogs and Pigs in Palau.

Leptospirosis is a zoonotic disease caused by the pathogenic spirochaetes of the genus Leptospira. It is a public health concern in the Pacific Islands and is considered endemic in Palau. However, information on the genotypes and serotypes of causative Leptospira spp. in the country is limited. In this study, we isolated leptospires and detected antileptospiral antibodies in dogs and pigs. The isolates were characterized using a serological method and whole-genome sequencing. Leptospira interrogans was isolated from five of the 20 symptomatic dogs and one of the 58 healthy pigs. Their serogroups were identified as Icterohaemorrhagiae and Pyrogenes; however, the serogroup of one isolate could not be determined. Anti-Leptospira antibodies were detected in 14.4% (26/181) of the dogs and 20% (10/50) of the pigs. The reactive serogroups in dogs and pigs were almost identical, except for the Panama serogroup. Core genome multilocus sequence typing revealed that five of the six core genome sequence types (cgSTs) were newly identified in this study. The cgSTs from the serogroup Icterohaemorrhagiae isolates belonged to the same group as the Copenhageni and Icterohaemorrhagiae serovars isolated in other countries, whereas no similar cgSTs were identified in the Pyrogenes or unidentified serogroup strains. We demonstrated a high incidence of canine and porcine leptospirosis and identified new L. interrogans genotypes (cgSTs) circulating in Palau. Further investigations are needed to determine whether dogs and pigs serve as maintenance hosts for newly identified L. interrogans genotypes and whether they pose a risk of leptospirosis transmission to humans.

Increased resistance against tellurite is conferred by a mutation in the promoter region of uncommon tellurite resistance gene tehB in the ter-negative Shiga toxin-producing Escherichia coli O157:H7.

Resistance to potassium tellurite (PT) is an important indicator in isolating Shiga toxin-producing Escherichia coli (STEC) O157:H7 and other major STEC serogroups. Common resistance determinant genes are encoded in the ter gene cluster. We found an O157:H7 isolate that does not harbor ter but is resistant to PT. One nonsynonymous mutation was found in another PT resistance gene, tehA, through whole-genome sequence analyses. To elucidate the contribution of this mutation to PT resistance, complementation of tehA and the related gene tehB in isogenic strains and quantitative RT‒PCR were performed. The results indicated that the point mutation not only changed an amino acid of tehA, but also was positioned on a putative internal promoter of tehB and increased PT resistance by elevating tehB mRNA expression. Meanwhile, the amino acid change in tehA had negligible impact on the PT resistance. Comprehensive screening revealed that 2.3% of O157:H7 isolates in Japan did not harbor the ter gene cluster, but the same mutation in tehA was not found. These results suggested that PT resistance in E. coli can be enhanced through one mutational event even in ter-negative strains. IMPORTANCE: Selective agents are important for isolating Shiga toxin-producing Escherichia coli (STEC) because the undesirable growth of microflora should be inhibited. Potassium tellurite (PT) is a common selective agent for major STEC serotypes. In this study, we found a novel variant of PT resistance genes, tehAB, in STEC O157:H7. Molecular experiments clearly showed that one point mutation in a predicted internal promoter region of tehB upregulated the expression of the gene and consequently led to increased resistance to PT. Because tehAB genes are ubiquitous across E. coli, these results provide universal insight into PT resistance in this species.

Synthetic phage-based approach for sensitive and specific detection of Escherichia coli O157.

Escherichia coli O157 can cause foodborne outbreaks, with infection leading to severe disease such as hemolytic-uremic syndrome. Although phage-based detection methods for E. coli O157 are being explored, research on their specificity with clinical isolates is lacking. Here, we describe an in vitro assembly-based synthesis of vB_Eco4M-7, an O157 antigen-specific phage with a 68-kb genome, and its use as a proof of concept for E. coli O157 detection. Linking the detection tag to the C-terminus of the tail fiber protein, gp27 produces the greatest detection sensitivity of the 20 insertions sites tested. The constructed phage detects all 53 diverse clinical isolates of E. coli O157, clearly distinguishing them from 35 clinical isolates of non-O157 Shiga toxin-producing E. coli. Our efficient phage synthesis methods can be applied to other pathogenic bacteria for a variety of applications, including phage-based detection and phage therapy.

Unveiling the role of preceding seasonal influenza in the development of bacteremic pneumococcal pneumonia in older adults before the COVID-19 pandemic in Japan.

OBJECTIVE: We aimed to investigate the impact of preceding seasonal influenza on the clinical characteristics of adult patients with invasive pneumococcal disease (IPD) in Japan. METHODS: Data for 1722 adult patients with IPD were analyzed before (2017-2019) and during the COVID-19 pandemic (2020-2022). RESULTS: The seasonal influenza epidemic disappeared soon after the emergence of the pandemic. Compared with that before the pandemic (66.7%), we observed a lower bacteremic pneumonia proportion in patients with IPD during the pandemic (55.6%). The clinical presentations of IPD cases significantly differed between those with and without preceding influenza. The proportion of bacteremic pneumonia was higher in IPD patients with preceding influenza than in those without in both younger (44.9% vs 84.2%) and older adults (65.5% vs 87.0%) before the pandemic. The case fatality rate was significantly higher in IPD patients with preceding influenza (28.3%) than in those without (15.3%) in older adults before the pandemic (P = 0.020). Male and aging are high risk factors for death in older patients with IPD who had preceding influenza. CONCLUSION: Our study reveals that preceding seasonal influenza plays a role in the development of bacteremic pneumococcal pneumonia, increasing the risk of death in older adults.

Comparative evaluation of analytical pipelines for illumina short- and nanopore long-read 16S rRNA gene amplicon sequencing with mock microbial communities.

Utility of a recently developed long-read pipeline, Emu, was assessed using an expectation-maximization algorithm for accurate read classification. We compared it to conventional short- and long-read pipelines, using well-characterized mock bacterial samples. Our findings highlight the necessity of appropriate data-processing for taxonomic descriptions, expanding our understanding of the precise microbiome.

Mucosal adjuvanticity and mucosal booster effect of colibactin-depleted probiotic Escherichia coli membrane vesicles.

There is a growing interest in development of novel vaccines against respiratory tract infections, due to COVID-19 pandemic. Here, we examined mucosal adjuvanticity and the mucosal booster effect of membrane vesicles (MVs) of a novel probiotic E. coli derivative lacking both flagella and potentially carcinogenic colibactin (ΔflhDΔclbP). ΔflhDΔclbP-derived MVs showed rather strong mucosal adjuvanticity as compared to those of a single flagellar mutant strain (ΔflhD-MVs). In addition, glycoengineered ΔflhDΔclbP-MVs displaying serotype-14 pneumococcal capsular polysaccharide (CPS14+MVs) were well-characterized based on biological and physicochemical parameters. Subcutaneous (SC) and intranasal (IN) booster effects of CPS14+MVs on systemic and mucosal immunity were evaluated in mice that have already been subcutaneously prime-immunized with the same MVs. With a two-dose regimen, an IN boost (SC-IN) elicited stronger IgA responses than homologous prime-boost immunization (SC-SC). With a three-dose regimen, serum IgG levels were comparable among all tested regimens. Homologous immunization (SC-SC-SC) elicited the highest IgM responses among all regimens tested, whereas SC-SC-SC failed to elicit IgA responses in blood and saliva. Furthermore, serum IgA and salivary SIgA levels were increased with an increased number of IN doses administrated. Notably, SC-IN-IN induced not only robust IgG response, but also the highest IgA response in both serum and saliva among the groups. The present findings suggest the potential of a heterologous three-dose administration for building both systemic and mucosal immunity, e.g. an SC-IN-IN vaccine regimen could be beneficial. Another important observation was abundant packaging of colibactin in MVs, suggesting increased applicability of ΔflhDΔclbP-MVs in the context of vaccine safety.

Individual Atg8 paralogs and a bacterial metabolite sequentially promote hierarchical CASM-xenophagy induction and transition.

Atg8 paralogs, consisting of LC3A/B/C and GBRP/GBRPL1/GATE16, function in canonical autophagy; however, their function is controversial because of functional redundancy. In innate immunity, xenophagy and non-canonical single membranous autophagy called "conjugation of Atg8s to single membranes" (CASM) eliminate bacteria in various cells. Previously, we reported that intracellular Streptococcus pneumoniae can induce unique hierarchical autophagy comprised of CASM induction, shedding, and subsequent xenophagy. However, the molecular mechanisms underlying these processes and the biological significance of transient CASM induction remain unknown. Herein, we profile the relationship between Atg8s, autophagy receptors, poly-ubiquitin, and Atg4 paralogs during pneumococcal infection to understand the driving principles of hierarchical autophagy and find that GATE16 and GBRP sequentially play a pivotal role in CASM shedding and subsequent xenophagy induction, respectively, and LC3A and GBRPL1 are involved in CASM/xenophagy induction. Moreover, we reveal ingenious bacterial tactics to gain intracellular survival niches by manipulating CASM-xenophagy progression by generating intracellular pneumococci-derived H2O2.

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.

Pneumococcal sialidase promotes bacterial survival by fine-tuning of pneumolysin-mediated membrane disruption.

Pneumolysin (Ply) is an indispensable cholesterol-dependent cytolysin for pneumococcal infection. Although Ply-induced disruption of pneumococci-containing endosomal vesicles is a prerequisite for the evasion of endolysosomal bacterial clearance, its potent activity can be a double-edged sword, having a detrimental effect on bacterial survivability by inducing severe endosomal disruption, bactericidal autophagy, and scaffold epithelial cell death. Thus, Ply activity must be maintained at optimal levels. We develop a highly sensitive assay to monitor endosomal disruption using NanoBiT-Nanobody, which shows that the pneumococcal sialidase NanA can fine-tune Ply activity by trimming sialic acid from cell-membrane-bound glycans. In addition, oseltamivir, an influenza A virus sialidase inhibitor, promotes Ply-induced endosomal disruption and cytotoxicity by inhibiting NanA activity in vitro and greater tissue damage and bacterial clearance in vivo. Our findings provide a foundation for innovative therapeutic strategies for severe pneumococcal infections by exploiting the duality of Ply activity.

Genetic characterization of multidrug-resistant Escherichia coli harboring colistin-resistant gene isolated from food animals in food supply chain.

Colistin is widely used for the prophylaxis and treatment of infectious disease in humans and livestock. However, the global food chain may actively promote the dissemination of colistin-resistant bacteria in the world. Mobile colistin-resistant (mcr) genes have spread globally, in both communities and hospitals. This study sought to genomically characterize mcr-mediated colistin resistance in 16 Escherichia coli strains isolated from retail meat samples using whole genome sequencing with short-read and long-read platforms. To assess colistin resistance and the transferability of mcr genes, antimicrobial susceptibility testing and conjugation experiments were conducted. Among the 16 isolates, 11 contained mcr-1, whereas three carried mcr-3 and two contained mcr-1 and mcr-3. All isolates had minimum inhibitory concentration (MIC) for colistin in the range 1-64 µg/mL. Notably, 15 out of the 16 isolates demonstrated successful transfer of mcr genes via conjugation, indicative of their presence on plasmids. In contrast, the KK3 strain did not exhibit such transferability. Replicon types of mcr-1-containing plasmids included IncI2 and IncX4, while IncFIB, IncFII, and IncP1 contained mcr-3. Another single strain carried mcr-1.1 on IncX4 and mcr-3.5 on IncP1. Notably, one isolate contained mcr-1.1 located on a chromosome and carrying mcr-3.1 on the IncFIB plasmid. The chromosomal location of the mcr gene may ensure a steady spread of resistance in the absence of selective pressure. Retail meat products may act as critical reservoirs of plasmid-mediated colistin resistance that has been transmitted to humans.

IL-27 regulates the differentiation of follicular helper NKT cells via metabolic adaptation of mitochondria.

Invariant natural killer T (iNKT) cells are innate-like T lymphocytes that express an invariant T cell receptor α chain and contribute to bridging innate and acquired immunity with rapid production of large amounts of cytokines after stimulation. Among effecter subsets of iNKT cells, follicular helper NKT (NKTFH) cells are specialized to help B cells. However, the mechanisms of NKTFH cell differentiation remain to be elucidated. In this report, we studied the mechanism of NKTFH cell differentiation induced by pneumococcal surface protein A and α-galactosylceramide (P/A) vaccination. We found that Gr-1+ cells helped iNKT cell proliferation and NKTFH cell differentiation in the spleen by producing interleukin-27 (IL-27) in the early phase after vaccination. The neutralization of IL-27 impaired NKTFH cell differentiation, which resulted in compromised antibody production and diminished protection against Streptococcus pneumoniae infection by the P/A vaccine. Our data indicated that Gr-1+ cell-derived IL-27 stimulated mitochondrial metabolism, meeting the energic demand required for iNKT cells to differentiate into NKTFH cells. Interestingly, Gr-1+ cell-derived IL-27 was induced by iNKT cells via interferon-γ production. Collectively, our findings suggest that optimizing the metabolism of iNKT cells was essential for acquiring specific effector functions, and they provide beneficial knowledge on iNKT cell-mediated vaccination-mediated therapeutic strategies.

Epidemiological shifts in and impact of COVID-19 on streptococcal toxic shock syndrome in Japan: A genotypic analysis of group A Streptococcus isolates.

OBJECTIVES: Streptococcal toxic shock syndrome (STSS) is caused by group A Streptococcus (GAS; Streptococcus pyogenes) strains. In Japan, the number of STSS cases has decreased; however, the underlying reason remains unclear. Moreover, information on distribution and prevalence of specific emm types in STSS cases is scarce. Hence, we investigated the reason for the decreased number of STSS cases in Japan. METHODS: We genotyped emm of 526 GAS isolates obtained from 526 patients with STSS between 2019 and 2022. The distributions of emm types in each year were compared. RESULTS: The emm1 type was predominant, with the highest proportion in 2019, which decreased after 2020 following the onset of the coronavirus disease 2019 (COVID-19) pandemic. Strains isolated during the pandemic correlated with strains associated with skin infection, whereas those isolated during the prepandemic period correlated with strains associated with both throat and skin infections. The decrease in the annual number of STSS cases during the COVID-19 pandemic could be due to a decreased proportion of strains associated with pharyngeal infections. CONCLUSIONS: Potential associations between pandemic and STSS numbers with respect to public health measures, such as wearing masks and changes in healthcare-seeking behavior, may have affected the number of GAS-induced infections.

Isolation and whole-genome sequencing analysis of Escherichia fergusonii harboring a heat-labile enterotoxin gene from retail chicken meat in Okinawa, Japan.

This study aimed to reveal the prevalence of heat-labile enterotoxin (LT) gene-positive Escherichia fergusonii in retail chicken meat and genetically characterize these strains. E. fergusonii harboring LT gene was isolated from 6 out of 60 (10%) retail chicken samples in Okinawa, Japan. Whole-genome sequencing analysis revealed that LT gene-positive E. fergusonii from chicken meat and feces contain an IncFII plasmid harboring elt1AB, and suggested to spread clonally to retail chicken through fecal contamination. Additionally, it was found that these strains harbor multidrug-resistant genes on their plasmids. Their pathogenicity and continuous monitoring are required for confirmation.