Relapsing bronchopneumonia due to community-associated methicillin-resistant Staphylococcus aureus: a case report.

BACKGROUND: The emergence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has increased the incidence of community-onset MRSA infection. Respiratory tract infections caused by MRSA has been noted for their severity; however, repeated relapses that require extended antibiotic therapy are rare. CASE PRESENTATION: We report a case of relapsing bronchopneumonia caused by CA-MRSA in a 56-year-old man. The patient responded to antibiotics, but repeatedly relapsed after stopping treatment. MRSA was consistently isolated from airway specimens during each relapse. Extended oral antibiotic treatment with trimethoprim/sulfamethoxazole (TMP/SMX) for 6 months achieved infection control. Whole-genome sequencing of the isolated strain revealed that the causative agent was sequence type (ST)1/staphylococcal cassette chromosome mec (SCCmec) type IVa, a clone that is rapidly increasing in Japan. DISCUSSION AND CONCLUSIONS: This patient had an unusual course of MRSA bronchopneumonia with repeated relapses. Although the choice of antibiotics for long-term use in MRSA respiratory tract infections has not been well established, TMP/SMX was effective and well tolerated for long-term therapy in this case. The clinical course of infections related to the rapid emerging clone, ST1/SCCmec type IVa warrants further attention.

"Rich arginine and strong positive charge" antimicrobial protein protamine: From its action on cell membranes to inhibition of bacterial vital functions.

Protamine, an antimicrobial protein derived from salmon sperm with a molecular weight of approximately 5 kDa, is composed of 60-70 % arginine and is a highly charged protein. Here, we investigated the mechanism of antimicrobial action of protamine against Cutibacterium acnes (C. acnes) focusing on its rich arginine content and strong positive charge. Especially, we focused on the attribution of dual mechanisms of antimicrobial protein, including membrane disruption or interaction with intracellular components. We first determined the dose-dependent antibacterial activity of protamine against C. acnes. In order to explore the interaction between bacterial membrane and protamine, we analyzed cell morphology, zeta potential, membrane permeability, and the composition of membrane fatty acid. In addition, the localization of protamine in bacteria was observed using fluorescent-labeled protamine. For investigation of the intracellular targets of protamine, bacterial translation was examined using a cell-free translation system. Based on our results, the mechanism of the antimicrobial action of protamine against C. acnes is as follows: 1) electrostatic interactions with the bacterial cell membrane; 2) self-internalization into the bacterial cell by changing the composition of the bacterial membrane; and 3) inhibition of bacterial growth by blocking translation inside the bacteria. However, owing to its strong electric charge, protamine can also interact with DNA, RNA, and other proteins inside the bacteria, and may inhibit various bacterial life processes beyond the translation process.

Delayed immune-related adverse events in long-responders of immunotherapy: a single-center experience.

BACKGROUND: Immune-checkpoint inhibitors (ICIs) often cause immune-related adverse events (irAEs). The spectrum of irAEs and their managements has been partially clarified, however the knowledge on time-course of irAEs is not well understood. METHODS: A retrospective study based on the medical record was performed. The study subjects were consisting of patients with various types of solid tumors for whom ICIs (nivolumab, pembrolizumab, durvalumab, atezolizumab, nivolumab plus ipilimumab) were used between April 2016 and October 2021. We focused on irAEs developed more than 1-year after commencement ICIs (delayed irAE group) and compared with irAEs developed within 1-year (non-delayed irAE group) in terms of types and severity of irAEs. RESULTS: A total of 336 patients were enrolled in the study. Eighty-eight patients (26.2%) developed irAEs and 248 did not. Most of the patients developing irAEs were treated using PD-L1/PD-1 inhibitors. Eighty-one patients (24.1%) in non-delayed irAE group and 7 patients (2.1%) in delayed irAE group developed irAEs. The median onset of irAEs in the delayed irAE group was 18.6 months (range: 13.5-24.3). The types of irAEs observed in delayed irAE group were dermatitis (2 cases), pneumonitis (2 cases), nephritis (1 case), arthritis (1 case), and gastritis (1 case). The severity of irAEs was almost mild (≤G2), but one patient (.3%) developed G3 nephritis. CONCLUSION: PD-L1/PD-1 inhibitors frequently caused various irAEs but their severities were mostly tolerable. Few patients developed delayed irAE with mild toxities.

Effective Treatment of Lung Adenocarcinoma With a Novel SLC44A1-BRAF Fusion Using Pembrolizumab Followed by Trametinib: A Case Report.

The serine-threonine protein kinase B-RAF (BRAF) fusions are rarely observed in non-small cell lung cancer (NSCLC) accounting for less than 1%, and therapeutic evidence for molecular-targeted drugs is lacking, unlike for BRAF V600E mutation by RAF and MEK inhibitors. A 75-year-old female patient with no smoking history and mild renal dysfunction developed recurrent lung adenocarcinoma and was initially treated with pembrolizumab immunotherapy followed by chemotherapy using docetaxel showing a certain efficacy but the disease finally progressed. Comprehensive genome profiling showed a novel SLC44A1-BRAF fusion and the tumor progression was controlled with the MEK inhibitor trametinib. Because of the rarity of NSCLC with BRAF fusion, the description of this case would be helpful for the treatment strategy for such tumors.

Effects of Fe Ions, Ultraviolet Irradiation, and Heating on Microscopic Structures of Black Lacquer Films.

The chemical reaction between Fe and lacquer has been used to create the black color in lacquer coatings since ancient times. Here, the effects of Fe ion addition, UV irradiation, and heating on the microscopic structures of black lacquer films were investigated by using X-ray absorption near edge structure (XANES), extended X-ray absorption fine structure (EXAFS), Fourier transform-infrared spectroscopy (FT-IR), small-angle X-ray scattering (SAXS), and small angle neutron scattering (SANS). The EXAFS result indicated that heating and UV irradiation made the coordination structure of Fe3+ in the lacquer nonuniform, and that heating caused the greatest nonuniformity. The FT-IR, SAXS, and SANS results demonstrated that the microscopic structural changes in the black lacquer films were induced by both heating and UV irradiation, but the changes were different. Heating caused a substantial structural change on the nanoscale, and UV irradiation mainly caused changes in the molecular binding mode. The results provide important knowledge for analyzing archeological lacquer samples and for developing lacquer-based materials. This work also demonstrates the utility of the complementary use of XANES, EXAFS, FT-IR, SAXS, and SANS for nondestructive analysis of black lacquer in precious cultural relics.

Passive Smoking-Induced Mutagenesis as a Promoter of Lung Carcinogenesis.

INTRODUCTION: The International Agency for Research on Cancer has classified passive smoking (PS) or secondhand smoke exposure as a group 1 carcinogen linked to lung cancer. However, in contrast to active smoking, the mutagenic properties of PS remain unclear. METHODS: A consecutive cohort of 564 lung adenocarcinoma samples from female never-smokers, who provided detailed information about their exposure to PS during adolescence and in their thirties through a questionnaire, was prepared. Of these, all 291 cases for whom frozen tumor tissues were available were subjected to whole exome sequencing to estimate tumor mutational burden, and the top 84 cases who were exposed daily, or not, to PS during adolescence, in their thirties or in both periods, were further subjected to whole genome sequencing. RESULTS: A modest yet statistically significant increase in tumor mutational burden was observed in the group exposed to PS compared with the group not exposed to PS (median values = 1.44 versus 1.29 per megabase, respectively; p = 0.020). Instead of inducing driver oncogene mutations, PS-induced substantial subclonal mutations exhibiting APOBEC-type signatures, including SMAD4 and ADGRG6 hotspot mutations. A polymorphic APOBEC3A/3B allele-specific to the Asian population that leads to up-regulated expression of APOBEC3A accentuated the mutational load in individuals exposed daily to PS during adolescence. CONCLUSIONS: This study reveals that PS-induced mutagenesis can promote lung carcinogenesis. The APOBEC3A/3B polymorphism may serve as a biomarker for identifying passive nonsmoking individuals at high risk of developing lung cancer.

A Case of Solitary Pure Ground-glass Opacity Suspected of Being the Initial Presentation of Nonfibrotic Hypersensitivity Pneumonitis.

We herein report a rare case of hypersensitivity pneumonitis (HP) that was initially demonstrated as solitary pure ground-glass opacity (GGO) on chest computed tomography (CT). A 51-year-old woman with a history of breast cancer underwent follow-up CT, which revealed solitary pure GGO. The patient developed exertional dyspnea after two years, and CT revealed diffuse centrilobular nodules in addition to GGO, which had increased in size. An antigen avoidance test was performed to diagnose HP, leading to the resolution of CT abnormalities, including the GGO. Our findings suggested that nonfibrotic HP can present as solitary pure GGO.