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Background: Meticillin-resistant Staphylococcus aureus (MRSA) is the most common pathogen in orthopaedic surgical site infections (SSIs). However, few studies have investigated the transmission process of orthopaedic MRSA SSI., Aim: To investigate the transmission process of orthopaedic MRSA SSI using epidemiological and molecular analyses and to determine a method to prevent MRSA SSI in nosocomial orthopaedic surgery., Methods: Active MRSA surveillance, preoperative decolonization and contact precautions for MRSA-positive cases was performed at our institution. Changes in epidemic strains were evaluated and the possibility of transmission from patients in an orthopaedic ward of a Japanese tertiary-care hospital was assessed by genotyping stored MRSA strains. In addition, data on the prevalence of MRSA SSI, MRSA colonization, and use of an alcohol antiseptic agent (mL/patient-days) during 2005-2022 were retrospectively assessed., Findings: SCCmec type II strain in the SSI group decreased over time, associated with fewer outbreaks. Even during a period of high infection rates, no cases of transmission-induced SSI from nasal MRSA carriers were identified. The infection rate correlated negatively with the use of an alcohol antiseptic agent (r = -0.82; P < 0.0001). Two cases among five nasal carriers developed MRSA SSI caused by strains different from those related to nasal colonization., Conclusion: The infection control measures for transmission from the hospital reservoirs including strict adherence to hand hygiene and decolonization of carriers is likely to be important for the prevention of orthopaedic MRSA SSI. However, the need for contact precautions for decolonized nasal carriers might be low., (Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Introduction: In this study, we aimed to analyze the effectiveness of enhanced preventive measures against nosocomial COVID-19 Omicron outbreaks based on those encountered., Methods: We introduced PCR-based screening and syndromic surveillance, in addition to standard and transmission-based precautions, during a COVID-19 outbreak in three wards of Kagoshima University Hospital, a Japanese tertiary care hospital, in February 2022, amid the Omicron variant endemic. Furthermore, we analyzed the descriptive epidemiology and whole-genome sequencing (WGS) of positive SARS-CoV-2 PCR samples from this outbreak., Results: PCR-based screening tests were conducted following the identification of three cases through syndromic surveillance. As a result, 30 individuals tested positive for SARS-CoV-2, including 13 inpatients, five attendant family members, and 12 healthcare workers across the three wards. Notably, no new infections were observed within eight days following the implementation of preventive measures. Among the SARS-CoV-2 genomes analyzed (n = 16; 53.3%), all strains were identified as belonged to BA.1.1 variant. Detailed analysis of descriptive and molecular epidemiology, incorporating single-nucleotide polymorphism analysis of WGS and clarification of transmission links, considering two potential entry routes to the hospital., Conclusions: Introduction of additional preventive measures, including PCR-based screening and syndromic surveillance, in addition to WGS and descriptive epidemiology, is useful for the early intervention of nosocomial outbreaks and for revealing the transmission route of the COVID-19 Omicron variant., Competing Interests: Declaration of competing interest The authors declare no conflicts of interest., (Copyright © 2023 Japanese Society of Chemotherapy, Japanese Association for Infectious Diseases, and Japanese Society for Infection Prevention and Control. Published by Elsevier Ltd. All rights reserved.)

Japanese General Rules presented by the Japanese Breast Cancer Society have been long time applied in Japan. This classification uniquely adds subtypes into the group of invasive ductal carcinomas (IDC) and reported to be correlated to patients' clinical course. The latest St. Gallen consensus meeting reported the use of 5 molecules, and introduced alternative definition in the breast cancer classification. The purpose of this study is to relate the Japanese subgrouping of IDC with the 5 subtypes and to investigate whether these classifications could predict early and late recurrence and whether cytological diagnosis is influenced by the tumor phenotypes. Analyzing 127 cases, we observed that the Ki-67 labeling index (LI) of the 5 subtypes, luminal A, luminal B-Her2--/- Her2+, Her2-subtype and basal-like, is increased in this order. Though the Japanese histological groups, papillotubular, solid-tubular and scirrhous, included more or less those subtypes, the luminal types were more represented in papillotubular and scirrhous subtypes, and the solid-tubular type in non luminal subtypes. The Ki-67 LI 14% served as a cutoff for differentiating invasive from non-invasive ductal carcinomas. Breast cancers recur within 5 years after the clinical onset when the Ki-67 LI exceeded 14%. These data suggest that, (1) the intrinsic subtyping is an accurate modality in diagnosing breast cancers, (2) it can predict the recurrence duration, (3) the solid-tubular type of the Japanese classification is likely an aggressive form among breast cancers, and (4) the cytological diagnosis is presently a powerful tool in determining malignancy.