Evolutionary dynamics of the novel ST22-PT methicillin-resistant Staphylococcus aureus clone co-harbouring Panton-Valentine leucocidin and duplicated toxic shock syndrome toxin 1 genes.

OBJECTIVES: Globally, the isolation of community-associated methicillin-resistant Staphylococcus aureus (MRSA) harbouring both the Panton-Valentine leucocidin (PVL) and toxic shock syndrome toxin 1 (TSST-1) genes is rare. However, we encountered an outbreak of the ST22-PT clone exhibiting this phenotype in Japan. Notably, the TSST-1 gene was duplicated in most of the strains. This study aimed to elucidate the mechanisms underlying this gene duplication. METHODS: A total of 90 MRSA isolates were collected from the skin of outpatients in Fukuoka City, Japan, between 2017 and 2019. Whole-genome sequencing was performed on MRSA strains that were PVL and TSST-1 positive. RESULTS: A total of 43 (47.8%) strains produced TSST-1, 20 (22.2%) produced PVL, and 16 (17.8%) produced both. Fifteen isolates were classified as ST22/SCCmec type IVa (ST22-PT clone) and one as ST1/SCCmec type V (ST1-PT clone). Three distinct ST22-PT clones were identified: Fukuoka clone I (one PVL gene and one TSST-1 gene), Fukuoka clone II (addition of a TSST-1 gene to Fukuoka clone I), and Fukuoka clone III (marked by a chromosomal inversion in a large region from Fukuoka clone II). DISCUSSION: Fukuoka clone I may have integrated a novel pathogenicity island bearing the TSST-1 gene, leading to the emergence of Fukuoka clone II with a duplicated TSST-1 gene. This duplication subsequently instigated a chromosomal inversion in a large region owing to the homologous sequence surrounding TSST-1, giving rise to Fukuoka clone III. These findings provide crucial insights into the genetic evolution of MRSA.

Respiratory viral infections and Kawasaki disease: A molecular epidemiological analysis.

BACKGROUND/PURPOSE: Recent large-scale epidemiological studies have revealed significant temporal associations between certain viral infections and the subsequent development of Kawasaki disease (KD). Despite these associations, definitive laboratory evidence linking acute or recent viral infections to KD cases remains elusive. The objective of this study is to employ a molecular epidemiological approach to investigate the temporal association between viral infections and the development of KD. METHODS: We analyzed 2460 patients who underwent the FilmArray® Respiratory Panel test between April 2020 and September 2021. RESULTS: Following the application of inclusion criteria, 2402 patients were categorized into KD (n = 148), respiratory tract infection (n = 1524), and control groups (n = 730). The KD group exhibited higher positive rates for respiratory syncytial virus (RSV), human rhinovirus/enterovirus (hRV/EV), parainfluenza virus (PIV) 3, and adenovirus (AdV) compared to the control group. Additionally, coinfections involving two or more viruses were significantly more prevalent in the KD group. Notably, RSV-positive, hRV/EV-positive, and PIV3-positive KD patients exhibited a one-month delay in peak occurrence compared to non-KD patients positive for corresponding viruses. In contrast, AdV-positive KD cases did not show a one-month delay in peak occurrence. Moreover, anti-RSV, anti-PIV3, and anti-AdV antibody-positive rates or antibody titers were higher in RSV-, PIV3-, and AdV-positive KD cases, respectively, compared to non-KD cases with the same viral infections. CONCLUSION: Recent infection with RSV, PIV3, or AdV, occasionally in conjunction with other viruses, may contribute to the pathogenesis of KD as infrequent complications.

Clinical Usefulness of T-Cell Receptor Vß Repertoire Analysis for Differentiating Multisystem Inflammatory Syndrome in Japanese Children From Toxic Shock Syndrome and Kawasaki Disease.

The specific expansion of T-cell receptor ß chain variable region (TCR-Vß21.3 + ) CD4 + and CD8 + T cells was observed in Japanese patients with multisystem inflammatory syndrome in children. In contrast, these findings were not observed in patients with toxic shock syndrome and Kawasaki disease. T-cell receptor ß chain variable region repertoire analysis to detect specific expansion of Vß21.3 + T cells might be useful for differentiating multisystem inflammatory syndrome in children from toxic shock syndrome and Kawasaki disease.

CD14 down-modulation as a real-time biomarker in Kawasaki disease.

Objectives: The objectives of this study were to investigate the pathophysiology of Kawasaki disease (KD) from immunological and oxidative stress perspectives, and to identify real-time biomarkers linked to innate immunity and oxidative stress in KD. Methods: We prospectively enrolled 85 patients with KD and 135 patients with diverse conditions including immune, infectious and non-infectious diseases for this investigation. Flow cytometry was used to analyse the surface expression of CD14, CD38 and CD62L on monocytes, along with a quantitative assessment of CD14 down-modulation. Additionally, oxidative stress levels were evaluated using derivatives of reactive oxygen metabolites (d-ROMs) and antioxidant capacity measured by a free radical elective evaluator system. Results: During the acute phase of KD, we observed a prominent CD14 down-modulation on monocytes, reflecting the indirect detection of circulating innate immune molecular patterns. Moreover, patients with KD showed a significantly higher CD14 down-modulation compared with infectious and non-infectious disease controls. Notably, the surface expression of CD14 on monocytes was restored concurrently with responses to intravenous immunoglobulin and infliximab treatment in KD. Furthermore, d-ROM levels in patients with KD were significantly elevated compared with patients with infectious and non-infectious diseases. Following intravenous immunoglobulin treatment, oxidative stress levels decreased in patients with KD. Conclusion: Monitoring CD14 down-modulation on monocytes in real-time is a valuable strategy for assessing treatment response, distinguishing KD relapse from concomitant infections and selecting second-line therapy after IVIG treatment in KD patients. The interplay between inflammation and oxidative stress likely plays a crucial role in the development of KD.

Clinical Characteristics of Cryopyrin-Associated Periodic Syndrome and Long-Term Real-World Efficacy and Tolerability of Canakinumab in Japan: Results of a Nationwide Survey.

OBJECTIVE: We assess the clinical characteristics of patients with cryopyrin-associated periodic syndrome (CAPS) in Japan and evaluate the real-world efficacy and safety of interleukin-1 (IL-1) inhibitors, primarily canakinumab. METHODS: Clinical information was collected retrospectively, and serum concentrations of canakinumab and cytokines were analyzed. RESULTS: A total of 101 patients were included, with 86 and 15 carrying heterozygous germline and somatic mosaic mutations, respectively. We identified 39 mutation types, and the common CAPS-associated symptoms corresponded with those in previous reports. Six patients (5.9% of all patients) died, with four of the deaths caused by CAPS-associated symptoms. Notably, 73.7% of patients (100%, 79.6%, and 44.4% of familial cold autoinflammatory syndrome, Muckle-Wells syndrome, and chronic infantile neurological cutaneous articular syndrome/neonatal onset multisystem inflammatory disease, respectively) achieved complete remission with canakinumab, and early therapeutic intervention was associated with better auditory outcomes. In some patients, canakinumab treatment stabilized the progression of epiphysial overgrowth and improved height gain, visual acuity, and renal function. However, 23.7% of patients did not achieve inflammatory remission with crucial deterioration of organ damage, with two dying while receiving high-dose canakinumab treatment. Serological analysis of canakinumab and cytokine concentrations revealed that the poor response was not related to canakinumab shortage. Four inflammatory nonremitters developed inflammatory bowel disease (IBD)-unclassified during canakinumab treatment. Dual biologic therapy with canakinumab and anti-tumor necrosis factor-α agents was effective for IBD- and CAPS-associated symptoms not resolved by canakinumab monotherapy. CONCLUSION: This study provides one of the largest epidemiologic data sets for CAPS. Although early initiation of anti-IL-1 treatment with canakinumab is beneficial for improving disease prognosis, some patients do not achieve remission despite a high serum concentration of canakinumab. Moreover, IBD may develop in CAPS after canakinumab treatment.