Objectives: Carbapenem-resistant Enterobacterales (CRE) limit treatment options, and cefiderocol's efficacy can be compromised by regional carbapenemases. In this study, we aimed to characterize cefiderocol susceptibility distribution among Enterobacterales in Japan-specifically endemic strains producing IMP-type carbapenemases (IMP)-and explore the effect of IMP in mediating resistance. Methods: The susceptibility of 556 evaluable Enterobacterales isolates (from an initial 560 screened) to cefiderocol was assessed using disk diffusion and broth microdilution methods based on Clinical and Laboratory Standards Institute (CLSI) guidelines. Minimum inhibitory concentration (MIC) distributions across groups were compared using Kruskal-Wallis and Mann-Whitney U tests. Results: A total of 556 isolates yielded evaluable results. The cefiderocol susceptibility rate was 99.5 and 98.7% based on CLSI and European Committee on Antimicrobial Susceptibility Testing breakpoints, respectively. Notably, under both criteria, IMP-producing isolates exhibited a susceptibility rate of 99.6%, whereas non-CRE and non-extended-spectrum β-lactamase (ESBL) exhibited a susceptibility rate of 99.4%. Statistical analysis revealed that the ESBL-only group had higher MICs than the non-CRE/non-ESBL and IMP-only groups (both p < 0.001), whereas no significant difference was observed between the latter two (p = 0.083). Notably, the ESBL-only group exhibited higher MICs than those of isolates harboring both IMP and ESBL. Conclusions: These findings indicate a non-additive effect, in which the coexistence of multiple resistance enzymes does not necessarily increase cefiderocol resistance. The association between IMP and cefiderocol resistance may be limited. In specific enzyme combinations, its presence was even associated with lower MICs.

Objectives: This study aimed to characterize cefiderocol susceptibility distribution among Enterobacterales in Japan—specifically indigenous imipenemase (IMP)-producing strains—and explore the effect of IMP in mediating resistance. Methods: The susceptibility of 560 Enterobacterales isolates to cefiderocol was assessed using disk diffusion and broth microdilution methods based on Clinical and Laboratory Standards Institute (CLSI) guidelines. Minimum inhibitory concentration (MIC) distributions across groups were compared using Kruskal–Wallis and Mann–Whitney U tests. Results: A total of 556 isolates yielded evaluable results. The cefiderocol susceptibility rate was 99.5 and 98.7 % based on CLSI and European Committee on Antimicrobial Susceptibility Testing breakpoints, respectively. Notably, under both criteria, IMP-producing isolates exhibited a susceptibility rate of 99.6 %, whereas non-carbapenem-resistant Enterobacterales (CRE) and non-extended-spectrum β-lactamase (ESBL) exhibited 99.4 %. Statistical analysis revealed that the ESBL-only group had higher MICs than the non-CRE/non-ESBL and IMP-only groups (both p < 0.001), whereas no significant difference was observed between the latter two (p = 0.083). Notably, the ESBL-only group exhibited higher MICs than that of isolates harboring both IMP-type carbapenemase and ESBL. Conclusions: These findings indicate a non-additive effect, where the coexistence of multiple resistance enzymes does not necessarily increase cefiderocol resistance. The association between IMP and cefiderocol resistance may be limited. In specific enzyme combinations, its presence was even associated with lower MICs.

A novel vaccine modality is needed to generate both systemic and mucosal immunity in the respiratory tract, where pathogens are most likely to colonize and to initiate infection. Here, we demonstrated that intranasal immunization with probiotic Escherichia coli-derived membrane vesicles displaying serotype-14 pneumococcal capsule (CPS14+MVs) elicited potent IgG responses without adjuvant in mice, which were comparable and significantly superior to those of the injected CPS14+MVs and two licensed pneumococcal vaccines (conjugate and polysaccharide types), respectively. Notably, IgA class-switch recombination occurred only with intranasal CPS14+MVs immunization, resulting in robust secretory IgA (SIgA) production throughout a one-year-long-term study. Furthermore, the intranasal CPS14+MV vaccine induced both systemic and mucosal immunity regardless of mouse age at vaccination. Whereas opsonophagocytic activities were detected in sera of all immunization groups, only the intranasal CPS14+MV vaccine achieved dramatic pneumococcal clearance in the nasal cavity. Nevertheless, it failed to protect isogenic pIgR−/− mice, which are genetically impaired for SIgA translocation, from colonization of the respiratory tract. In conclusion, the present study could offer a novel vaccination strategy using chimeric probiotic E. coli MVs to provide antibody-mediated protection against pneumococcal colonization and infection.

BACKGROUND:Pneumococcal conjugated vaccine (PCV) has contributed to a dramatic reduction in invasive pneumococcal diseases. However, its impact upon nasopharyngeal carriage and upper respiratory tract infections is unclear. AIMS/OBJECTIVES:This study was aimed to evaluate the humoral immunity against Streptococcus pneumoniae in children with recurrent acute otitis media (rAOM) in the post PCV era. MATERIALS AND METHODS:We evaluated the humoral immunity against eight representative serotypes included in PCV13 (3, 6 A, 6B, 9 V, 14, 18 C, 19 F, and 23 F) among children with rAOM. RESULTS:Serum total immunoglobulin levels were typically within the normal range, but there was a decrease in IgG2 in >20% of cases. Serotype-specific antibody titers were not significantly different for any serotype in the rAOM group compared with the healthy controls, except for serotype 3. Conversely, the ability of serotype-specific antibodies to induce opsonophagocytic killing was increased in the rAOM group for three serotypes (6 A, 6B, and 14). There was a positive correlation between the titer of antibodies and the opsonophagocytic killing activity in five serotypes (6 A, 6B, 9 V, 19 F, and 23 F). CONCLUSION AND SIGNIFICANCE:Quantitative and qualitative evaluation of serotype-specific antibodies would be an important method for evaluating humoral immunity in children with rAOM.

Streptococcus pneumoniae (S. pneumoniae) causes otitis media, pneumonia, and invasive pneumococcal diseases (IPDs) such as meningitis and septicemia in humans. IPDs are fatal in children and can cause irreversible sequelae such as brain damage and impaired hearing. The introduction of 7- and 13-valent pneumococcal, conjugate, polysaccharide-based vaccines (PCV7, Prevnar 7®; and PCV13, Prevnar 13®) has decreased pediatric IPD infections. However, PCV13 provides limited protection against S. pneumoniae serotype 3. A new candidate pneumococcal vaccine antigen, pneumococcal surface protein A (PspA), which is found in almost all S. pneumoniae serotypes, addresses the drawbacks of CPS-based vaccines. In a previous study, the PspA3 + 2 protein was developed as a broad-spectrum vaccine candidate that combines PspA clades 2 and 3. We assessed whether vaccinating pregnant mice with PspA3 + 2 would transfer anti-PspA3 + 2 antibodies to pups, and if so, whether the transferred antibodies would protect against bacteremia caused by S. pneumoniae serotype 3. A PspA3 + 2 vaccine containing aluminum hydroxide gel (alum) and cytosine-phosphate-guanosine oligodeoxynucleotide K3 adjuvants induced anti-PspA antibodies in adult female mice, and an enzyme-linked immunosorbent assay revealed anti-PspA antibodies in serum samples from their offspring. Survival rates after lethal infection with S. pneumoniae serotype 3 were significantly higher among these neonates than in negative controls. These findings suggest that anti-PspA3 + 2 antibodies transferred from maternal mice vaccinated with PspA3 + 2 protect against bacteremia caused by S. pneumoniae serotype 3 in newborn pups.

Background:Natto consumption has been associated with improved cardiovascular and survival outcomes. Bacillus subtilis variant natto (B. subtilis var. natto) is essential for soybean fermentation in natto production. Recently, several cases of B. subtilis var. natto bacteremia have been reported, although the contribution of B. subtilis var. natto remains unclear. This study assessed the prevalence and clinical impact of B. subtilis var. natto in B. subtilis bacteremia. Methods:This retrospective cohort study analyzed medical records of patients with positive B. subtilis blood cultures at Tenri Hospital from 1 April 2016 to 31 March 2023. True bacteremia required portal-of-entry or, for intra-abdominal/abscess, 2-physician adjudication; if no portal, 2 or more same-day blood culture-positive sets. Genetic testing confirmed B. subtilis var. natto through specific mutations in the bioF and bioW genes. Results:Of 4634 positive blood cultures, 70 (1.5%) were identified as B. subtilis, with 69 (99%) classified as B. subtilis var. natto. Of these, 25 cases (36%) were confirmed as true bacteremia. The primary diagnoses included intra-abdominal infections, pneumonia, and urinary tract infection. The median patient age was 79 years, with 9 being women. The median Pitt bacteremia score was 0 (interquartile range: 0-1). Seven patients (28%) required urgent surgery or endoscopic procedures, while 4 (16%) died within 30 days. Conclusions:Most B. subtilis blood strains isolates were B. subtilis var. natto. This bacteremia carried significant severity, with a 16% 30-day mortality rate and 28% requiring urgent interventions. Clinicians should not dismiss B. subtilis var. natto, a probiotic strain, as harmless.

Clostridium butyricum, a probiotic commonly prescribed in Asia, most notably as MIYA-BM (Miyarisan Pharmaceutical Co., Ltd.; https://www.miyarisan.com), occasionally leads to bacteremia. The prevalence and characteristics of C. butyricum bacteremia and its bacteriologic and genetic underpinnings remain unknown. We retrospectively investigated patients admitted to Osaka University Hospital during September 2011-February 2023. Whole-genome sequencing revealed 5 (0.08%) cases of C. butyricum bacteremia among 6,576 case-patients who had blood cultures positive for any bacteria. Four patients consumed MIYA-BM, and 1 patient consumed a different C. butyricum-containing probiotic. Most patients had compromised immune systems, and common symptoms included fever and abdominal distress. One patient died of nonocclusive mesenteric ischemia. Sequencing results confirmed that all identified C. butyricum bacteremia strains were probiotic derivatives. Our findings underscore the risk for bacteremia resulting from probiotic use, especially in hospitalized patients, necessitating judicious prescription practices.

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.

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.

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.

Introduction Elucidating the characteristic odors of microbes can facilitate microorganism identification. This study aimed to evaluate the accuracy of microbial identification based on odor and its association with years of experience among microbiological technologists. Methods A cross-sectional study was conducted on February 19, 2023, in Osaka, Japan, in a laboratory capable of handling microorganisms that were rated at or below biosafety level 2. This study included 70 microbiological technologists (including 45 women) with a mean experience of 7.1 years (standard deviation, 5.7). Ten bacterial strains with distinct odors were selected. Participants were blindfolded and asked to identify the bacterial strains based on odor of cultured microbes alone. Linear and logistic regression analyses were used for data analysis. The primary outcome was the number of accurately identified bacterial strains per year of experience. Results The number of years of experience was not significantly associated with the accuracy of odor identification (regression coefficient = 0.037 [95% confidence interval: -0.038 to 0.113]). Additionally, generally low accuracy was noted in the identification of individual microbial species. Conclusions Our findings indicate that microorganism identification based solely on odor is challenging. Incorporating additional information, such as visual cues, may enhance the identification accuracy.

Background Ruthenibacterium lactatiformans, a Gram-stain-negative, rod-shaped, obligate anaerobic bacterium of the Oscillospiraceae family, has not been previously reported in human infections. This study reports the first case of bacteraemia and potential vertebral osteomyelitis caused by Ruthenibacterium lactatiformans. Case presentation An 82-year-old man with a history of diabetes, chronic renal failure, and prior spinal surgery for spondylolisthesis and spinal stenosis presented with fever and lower back pain. Magnetic resonance imaging revealed multiple vertebral osteomyelitis lesions. Initial blood cultures identified methicillin-resistant Staphylococcus aureus (MRSA), which prompted vancomycin treatment. However, repeated blood cultures not only confirmed persistent MRSA, but also detected Gram-negative bacilli (GNB). Despite surgical removal of the spinal hardware and antimicrobial therapy, the patient's osteomyelitis worsened, necessitating transfer for further management. Subsequent analysis using 16S rRNA gene sequencing identified the GNB as Ruthenibacterium lactatiformans. Conclusions This is the first documented instance of human infection with Ruthenibacterium lactatiformans, signifying its pathogenic potential in vertebral osteomyelitis. The involvement of anaerobic bacteria and the possibility of polymicrobial infections complicate the diagnosis and treatment of vertebral osteomyelitis. This report underscores the need for caution when identifying the causative organism and selecting an appropriate treatment.

Background Recent randomized clinical trials suggest that the effect of using cetylpyridinium chloride (CPC) mouthwashes on the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral load in COVID-19 patients has been inconsistent. Additionally, no clinical study has investigated the effectiveness of on-demand aqueous chlorine dioxide mouthwash against COVID-19.Methods We performed a randomized, placebo-controlled, open-label clinical trial to assess for any effects of using mouthwash on the salivary SARS-CoV-2 viral load among asymptomatic to mildly symptomatic adult COVID-19-positive patients. Patients were randomized to receive either 20 mL of 0.05% CPC, 10 mL of 0.01% on-demand aqueous chlorine dioxide, or 20 mL of placebo mouthwash (purified water) in a 1:1:1 ratio. The primary endpoint was the cycle threshold (Ct) values employed for SARS-CoV-2 salivary viral load estimation. We used linear mixed-effects models to assess for any effect of the mouthwashes on SARS-CoV-2 salivary viral load.Results Of a total of 96 eligible participants enrolled from November 7, 2022, to January 19, 2023, 90 were accepted for the primary analysis. The use of 0.05% CPC mouthwash was not shown to be superior to placebo in change from baseline salivary Ct value at 30 min (difference vs. placebo, 0.640; 95% confidence interval [CI], -1.425 to 2.706; P = 0.543); 2 h (difference vs. placebo, 1.158; 95% CI, -0.797 to 3.112; P = 0.246); 4 h (difference vs. placebo, 1.283; 95% CI, -0.719 to 3.285; P = 0.209); 10 h (difference vs. placebo, 0.304; 95% CI, -1.777 to 2.385; P = 0.775); or 24 h (difference vs. placebo, 0.782; 95% CI, -1.195 to 2.759; P = 0.438). The use of 0.01% on-demand aqueous chlorine dioxide mouthwash was also not shown to be superior to placebo in change from baseline salivary Ct value at 30 min (difference vs. placebo, 0.905; 95% CI, -1.079 to 2.888; P = 0.371); 2 h (difference vs. placebo, 0.709; 95% CI, -1.275 to 2.693; P = 0.483); 4 h (difference vs. placebo, 0.220; 95% CI, -1.787 to 2.226; P = 0.830); 10 h (difference vs. placebo, 0.198; 95% CI, -1.901 to 2.296; P = 0.854); or 24 h (difference vs. placebo, 0.784; 95% CI, -1.236 to 2.804; P = 0.447).Conclusions In asymptomatic to mildly symptomatic adults with COVID-19, compared to placebo, the use of 0.05% CPC and 0.01% on-demand aqueous chlorine dioxide mouthwash did not lead to a significant reduction in SARS-CoV-2 salivary viral load. Future studies of the efficacy of CPC and on-demand aqueous chlorine dioxide mouthwash on the viral viability of SARS-CoV-2 should be conducted using different specimen types and in multiple populations and settings.

Objectives The established effect of cetylpyridinium chloride (CPC) mouthwash on SARS-CoV-2 viral titers is unclear. No clinical trial has examined the impact of on-demand aqueous chlorine dioxide mouthwash on SARS-CoV-2 viral titer. Methods In this multicenter, 3-armed, randomized, open-label, placebo-controlled clinical trial involving mildly symptomatic COVID-19 patients, we randomly assigned them to receive 20 mL of 0.05% CPC, 10 mL of 0.01% on-demand aqueous chlorine dioxide, or 20 mL of purified water as a placebo mouthwash in a 1:1:1 ratio. The primary measurement was the SARS-CoV-2 viral titer in saliva, evaluated by a mixed-effects linear regression model. Results 49 patients received CPC mouthwash (n = 16), on-demand aqueous chlorine dioxide mouthwash (n = 16), and placebo (n = 17) between January 14, 2024, and February 20, 2024. 0.05% CPC mouthwash significantly reduced salivary viral titer at 10 minutes postuse (-0.97 log10 PFU/mL; 95% CI,-1.64 to-0.30; P = .004), while no such effect was observed at 30 minutes (difference vs placebo,-0.26 log10 PFU/mL; 95% CI,-0.92 to 0.40; P = .435) or 60 minutes (difference vs. placebo,-0.05 log10 PFU/mL; 95% CI,-0.68 to 0.58; P = .877). 0.01% on-demand chlorine dioxide mouthwash did not reduce salivary viral titer at 10 minutes, 30 minutes, or 60 minutes compared to placebo. Conclusions 10 minutes after using a 0.05% CPC mouthwash, the salivary viral titer of SARSCoV-2 decreased compared to placebo. 0.01% on-demand aqueous chlorine dioxide mouthwash and placebo had no significant difference in SARS-CoV-2 viral titers.

Mouthwashes containing cetylpyridinium chloride (CPC) or on-demand aqueous chlorine dioxide (ACD) have potential to reduce the salivary severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) load in individuals with SARS-CoV-2 infection. This study will evaluate the effect of CPC and on-demand ACD mouthwashes on salivary SARS-CoV-2 levels in individuals with acute asymptomatic or mild SARS-CoV-2 infection (COVID-19) staying in a residential recuperation facility in Osaka, Japan. This randomized, open-label clinical trial will include three equal-sized groups (CPC mouthwash, on-demand ACD mouthwash, and placebo), with 30 participants per group. A stratified replacement block method will be used to ensure balanced allocation based on symptom presence and days since symptom onset. Participants will use mouthwash at set times for 7 days or until the end of recuperation. Saliva samples will be collected at multiple time points and tested for SARS-CoV-2 using quantitative reverse transcription polymerase chain reaction. The primary outcome will be changes in salivary SARS-CoV-2 viral load 2 h after the first mouthwash use compared with the pre-mouthwash level. Secondary outcomes will include changes in salivary viral load and clinical parameters at different time points. This study was registered with the Japan Registry of Clinical Trials on 18 October 2022 (jRCTs051220107).

Streptococcus pneumoniae (pneumococcus) is a pathogenic gram-positive bacterium that causes pneumonia, meningitis, and sepsis. Pneumococcal surface protein A (PspA) induces antibodies that protect against lethal infections by pneumococci. PspA is a choline-binding protein present on the cell surface of almost all pneumococcal strains and is a non-capsular polysaccharide vaccine candidate. For research and development of PspAbased vaccines, an in-vitro test system to measure the activity of functional antibodies capable of killing pneumococci is essential. The opsonophagocytic killing (OPK) assay is used to evaluate the opsonic activity of functional antibodies induced by capsular polysaccharide (CPS)-based vaccines (standard OPK assay). Despite the potential of anti-PspA antibodies to protect against lethal infections in mice, the standard OPK assay fails to evaluate anti-PspA antibodies. Using a pneumococcal surface protein C-deficient strain and extending the incubation time of opsonized bacteria, complement, and HL-60 cells reportedly results in enhanced bactericidal activity (modified OPK assay). We aimed to measure the bactericidal activity of anti-PspA antibodies in intact pneumococcal strains. We optimized the pneumococcal culture method used in the OPK assay to increase the efficiency of anti-PspA antibody-mediated phagocytosis of HL-60 cells. As thick capsules hinder phagocytosis, we attempted to obtain pneumococci with thin capsules through an improved culture method. As pneumococci attached to cells exhibit thin capsules, pneumococci cultured in Todd Hewitt yeast extract (THY) broth were spread on blood agar plates and incubated for 4 h. cpsA mRNA transcript levels in pneumococci cultured on blood agar were lower than those in pneumococci cultured in THY broth. OPK activity against pneumococci expressing PspA of clades 1-5 was reasonably well detected using pneumococci cultured on blood agar in the modified OPK assay. The modified OPK assay for anti-PspA antibody using pneumococci cultured on blood agar represents a useful assay to determine the killing activity of functional anti-PspA antibodies against pneumococci.

An 84-year-old man in Japan who had undergone endovascular aortic repair 9 years earlier had an infected aneurysm develop. We detected Desulfovibrio desulfuricans MB at the site. The patient recovered after surgical debridement, artificial vessel replacement, and appropriate antimicrobial therapy. Clinicians should suspect Desulfovibrio spp. infection in similar cases.

We fabricated Si nanopillars array mimicking the cicada wing surface. We evaluated its antibacterial and bactericidal properties against antimicrobial resistant (AMR) bacteria and its WT bacteria by comparison with flat Si substrates. The results show that Si nanopillars array has superior antibacterial property for AMR and WT E. coli.

Background Although vaccination is recommended for protection against invasive pneumococcal disease, the frequency of pneumococcal pneumonia is still high worldwide. In fact, no vaccines are effective for all pneumococcal serotypes. Fusion pneumococcal surface protein A (PspA) has been shown to induce a broad range of cross-reactivity with clinical isolates and afford cross-protection against pneumococcal challenge in mice. Furthermore, we developed prime-boost-type mucosal vaccines that induce both antigen-specific IgG in serum and antigen-specific IgA in targeted mucosal organs in previous studies. We investigated whether our prime-boost-type immunization with a fusion PspA was effective against pneumococcal infection in mice and cynomolgus macaques. Methods C57BL/6 mice were intramuscularly injected with fusion PspA combined with CpG oligodeoxynucleotides and/or curdlan. Six weeks later, PspA was administered intranasally. Blood and bronchoalveolar lavage fluid were collected and antigen-specific IgG and IgA titers were measured. Some mice were given intranasal Streptococcus pneumoniae and the severity of infection was analyzed. Macaques were intramuscularly injected with fusion PspA combined with CpG oligodeoxynucleotides and/or curdlan at week 0 and week 4. Then, 13 or 41 weeks later, PspA was administered intratracheally. Blood and bronchoalveolar lavage fluid were collected and antigen-specific IgG and IgA titers were measured. Some macaques were intranasally administered S. pneumoniae and analyzed for the severity of pneumonia. Results Serum samples from mice and macaques injected with antigens in combination with CpG oligodeoxynucleotides and/or curdlan contained antigen-specific IgG. Bronchial samples contained antigen-specific IgA after the fusion PspA boosting. This immunization regimen effectively prevented S. pneumoniae infection. Conclusions Prime-boost-type immunization with a fusion PspA prevented S. pneumoniae infection in mice and macaques.

Abstract Background Clostridium butyricum (C. butyricum) is a strictly anaerobic, Gram-positive, spore-forming bacillus named for its capacity to produce high amounts of butyric acid. Some strains of C. butyricum involved in infectious diseases are known to be currently used as probiotics in Asia. Especially in Japan, MIYA-BM® is one of the probiotics commonly used as prescription drugs and it contains C. butyricum MIYAIRI 588 strain (CBM588). On the other hand, other strains involved in infectious diseases are known to be pathogenic. Bacteremia due to C. butyricum is a rare condition, and the prevalence, clinical features, and bacteriological and genetic origins of the condition are unknown. Methods We conducted a retrospective cohort study of medical records of patients to detect cases of C. butyricum bacteremia in Osaka University Hospital from September 19, 2011, to February 5, 2023. We analyzed the whole-genome sequencing of C. butyricum strains from positive blood culture samples, as well as strains from the probiotic MIYA-BM®. We also analyzed to determine the homology between these strains. Results Out of a total of 6576 positive blood culture samples, we detected five cases (0.08%) of bacteremia due to C. butyricum. Whole-genome analysis showed that the genes of each strain had only 1-33 mutations compared to the genes of the CBM588 strain, identifying them as the same clone derived from MIYA-BM®. The detail of case characteristics is shown in Table 1. All patients had bacteremia during hospitalization, with two male and three female patients. Four patients had concurrent use of MIYA-BM®. Four patients had immunocompromised conditions, and two patients had end-stage kidney disease on dialysis. All patients had a fever and abdominal symptoms such as diarrhea and pain. A patient with non-occlusive mesenteric ischemia died within 90 days.Table.Detailed clinical and microbiological information on five cases. Conclusion All C. butyricum strains detected from blood cultures in our hospital were derived from probiotics. Although C. butyricum bacteremia is rare condition, the use of MIYA-BM® use in hospitalized patients with multiple medical interventions is considered to cause C. butyricum bacteremia. Disclosures All Authors: No reported disclosures