Clinical Characteristics of Corynebacterium ulcerans Infection, Japan.

Corynebacterium ulcerans is a closely related bacterium to the diphtheria bacterium C. diphtheriae, and some C. ulcerans strains produce toxins that are similar to diphtheria toxin. C. ulcerans is widely distributed in the environment and is considered one of the most harmful pathogens to livestock and wildlife. Infection with C. ulcerans can cause respiratory or nonrespiratory symptoms in patients. Recently, the microorganism has been increasingly recognized as an emerging zoonotic agent of diphtheria-like illness in Japan. To clarify the overall clinical characteristics, treatment-related factors, and outcomes of C. ulcerans infection, we analyzed 34 cases of C. ulcerans that occurred in Japan during 2001-2020. During 2010-2020, the incidence rate of C. ulcerans infection increased markedly, and the overall mortality rate was 5.9%. It is recommended that adults be vaccinated with diphtheria toxoid vaccine to prevent the spread of this infection.

Attitudes of Medical Students toward COVID-19 Vaccination: Who Is Willing to Receive a Third Dose of the Vaccine?

Medical students may come in contact with individuals infected with COVID-19 in their clinical rotations. A high level of acceptance of vaccination is needed for them to protect their health and the health of patients from this disease. The objectives of this study were to (1) obtain information on medical students' attitudes toward COVID-19 vaccination, (2) assess factors associated with students' attitudes, and (3) identify predictors of their willingness to receive a third dose of the COVID-19 vaccine. Using a cross-sectional design, we conducted a questionnaire survey of medical students in July 2021. For this survey, we employed a 15-item questionnaire specifically developed to assess the students' attitudes toward COVID-19 vaccination. Of the 742 distributed questionnaires, 496 (294 males and 202 females) were completed. Among all the participants, 89.1% (442/496) received the second dose of the vaccine, and 90.7% (450/496) indicated that they would hypothetically receive the COVID-19 vaccine in the future. Furthermore, 84.5% (419/496) of all the participants were willing to receive a third dose of the vaccine. Regarding willingness to receive a third dose of the COVID-19 vaccine, multiple logistic regression models showed that students' grade and their responses to Q1 (positive attitude toward vaccination), Q9 (belief in the protection offered by COVID-19 vaccination), Q10 (concern about the excessively rapid development of COVID-19 vaccines), Q12 (need for aspects of pre-pandemic life), and Q14 (concern about the sustainability of immunity) had significant associations with this outcome. Confidence in vaccines, relaxation of mobility restrictions, and concern about the sustainability of immunity motivate willingness to receive a third dose of the COVID-19 vaccine in medical students.

Transmission of toxigenic Corynebacterium ulcerans infection with airway obstruction from cats to a human.

BACKGROUND: Infections caused by Corynebacterium ulcerans, a zoonotic pathogen, have been reported worldwide. This microorganism is known to produce the diphtheria toxin and cause diphtheria-like illness. CASE PRESENTATION: A 63-year-old woman with a history of diabetes and hypertension developed cold and flu-like symptoms, which gradually progressed into respiratory distress. Therefore, the patient was intubated for dyspnea with pseudomembrane formation. A toxin-producing strain of C. ulcerans was identified, also detected in the patient's domestic cats. Multilocus sequence typing confirmed all strains, including the patient's isolate, as ST337. CONCLUSION: Multilocus sequence typing revealed zoonotic transmission of C. ulcerans from domestic cats to a human.

Case Report: Acute Amebic Colitis Triggered by Colonoscopy: Exacerbation of Asymptomatic Chronic Infection with Entamoeba histolytica Accompanied by Dysbiosis.

Recent data show that the gut microbiome plays a role in determining the clinical outcome of Entamoeba histolytica infection. We report the case of a patient who developed recurrent acute amebic colitis (second episode of acute colitis) after colonoscopy. Genotyping of E. histolytica revealed that she developed a second episode of acute amebic colitis with the same genotype as that of the first episode, indicating chronic infection had persisted asymptomatically for > 10 months between the first and second episodes. Analysis of the gut microbiome, in addition to the clinical findings, suggested that dysbiosis at colonoscopy induced the change in the clinical form of E. histolytica infection from asymptomatic chronic infection to symptomatic colitis.

Chlamydophilal antigens induce foam cell formation via c-Jun NH2-terminal kinase.

Chlamydophila pneumoniae is known to be associated with atherosclerosis. Recent studies have reported that components of Chlamydophila pneumoniae (chlamydophilal antigens) induce foam cell formation in macrophages. However, the mechanism of foam cell formation induced by chlamydophilal antigens has yet to be elucidated. In this paper, we first found that mitogen-activated protein kinases including extracellular signal-regulated kinase, p38 and c-Jun NH2 terminal kinase are phosphorylated after stimulation by chlamydophilal antigens. We then showed that chlamydophilal antigens induce foam cell formation mainly via c-Jun NH2 terminal kinase. Finally, we demonstrated that foam cell formation and phosphorylation of mitogen-activated protein kinases induced by chlamydophilal antigens are mainly recognized through Toll-like receptor 2. These results collectively indicated that chlamydophilal antigens induce foam cell formation mainly via Toll-like receptor 2 and c-Jun NH2 terminal kinase.

Relationship between the initial dose of micafungin and its efficacy in patients with candidemia.

Micafungin, the first licensed echinocandin in Japan, has shown excellent in vitro and in vivo activity against all Candida species. However, the appropriate dose for the initial treatment of candidemia remains to be determined. In this study, we retrospectively examined the relationship between the clinical outcome of candidemia and the initial dose of micafungin. Patients were divided into two groups according to the initial dose of micafungin administered: group I (<2.25 mg/kg/day) and group II (>or=2.25 mg/kg/day). Micafungin produced an excellent 30-day clinical response in patients with candidemia, including Candida parapsilosis; the overall 30-day clinical response was 86%. The administration of higher doses of micafungin accelerated the clinical response and duration until the clinical response in group II was significantly shorter than that in group I (P = 0.021). However, no significant differences were observed in the 30-day mortality attributable to the fungal infection between the two groups. Considering these results, we recommend the administration of 2.25 mg/kg/day or more of micafungin in the initial treatment of patients with candidemia.

Macrophage tolerance induced by stimulation with Toll-like receptor 7/8 ligands.

The engagement of Toll-like receptors (TLRs) results in resistance to subsequent challenge with respective ligands in macrophages. Studies have shown that stimulation by ligands for TLR2, TLR4, TLR5 and TLR9 induces this state of hypo-responsiveness (homo-tolerance) towards subsequent stimulation with the same ligands. However, whether homo-tolerance is induced by the ligands of TLR7/8 has not been previously determined. We found that ligands for TLR7/8, namely ss-RNA from HIV and an imidazoquinoline compound, R848, induced macrophage tolerance, as judged by the production of the chemokine MIP-1beta. IRAK-1 phosphorylation was also inhibited in the tolerant cells after subsequent stimulation with R848, although no significant differences were observed in the protein levels of TLR7 between tolerant and non-tolerant cells. These results indicate that macrophage tolerance induced by TLR7/8 ligands is regulated at least at the level of IRAK-1 activation.