Objective. This study is aimed at investigating the pattern of change occurring in respiratory pathogens before and after the outbreak of COVID‐19, a type of viral pneumonia for which a pandemic was declared (March 2020). The results were analyzed by gender and age to identify the association between personal hygiene and prevention of infection by respiratory pathogens. Methods. A retrospective analysis was performed on 39,814 sputum, bronchial aspirate, and transtracheal aspirate samples obtained from 15,398 patients visiting a university hospital, located in Chungcheongnam‐do, South Korea, between January 2018 and December 2021. From 4,454 patients whose samples were culture positive for bacteria, 6,389 strains were isolated and further cultured. Results. The mean age of the outpatients with respiratory pathogens was 66.2 years, and the comparison of the culture test results by gender showed that 64.9% (2,892/4,454) were male and 35.1% (1,562/4,454) were female. Compared to the pre‐COVID‐19 pandemic period, the number of outpatients with a request for respiratory microbial cultures after the onset of the pandemic was reduced by 20.7% and the number of outpatients with a positive culture result was reduced by 23.0%. The number of respiratory samples received was reduced by 6.7% after the pandemic, while the sample positive rate was reduced by 18.3%. Among the isolated microbial strains, there was a significant decrease of 43.1% for the Acinetobacter baumannii complex, 60.5% for Streptococcus pneumoniae, 67.2% for Haemophilus influenzae, and 78.1% for Moraxella catarrhalis when compared with pre‐COVID‐19 levels. The distribution of respiratory microbial strains by age group showed that the highest percentage of isolated strains was in patients in their 70s. Conclusions. The improvements in personal hygiene due to the COVID‐19 pandemic exerted a substantial influence on the pattern of change in other common respiratory microorganisms, which highlights the importance of personal hygiene management in the prevention of respiratory infections.

Background and Objectives: In patients with congestive heart failure, brain natriuretic peptide (BNP) and N-terminal prohormone of brain natriuretic peptide (NT-proBNP) are released due to excessive heart muscle expansion; they can be used for the early detection, progress monitoring, and treatment of congestive heart failure. Recently, considerable efforts have been made to develop an NT-proBNP-based biomarker for detecting heart failure. This study attempts to develop a rapid and accurate congestive heart failure diagnostic kit using NT-proBNP. Materials and Methods: A new gene based on NT-proBNP was selected, recombined, and expressed in Escherichia coli strains, and then monoclonal antibodies were produced using the hybridoma technique. Additionally, antigen-antibody reactivity was confirmed using indirect enzyme-linked immunosorbent assay (ELISA). Furthermore, the first pair and full-strip pair tests were conducted to select candidate clones; these were applied to a rapid diagnosis kit based on gold conjugates and compared with other currently available antigens. Results: NT-proBNP-based antigens with high specificity and monoclonal antibodies were produced, and the optimal antigen-antibody reactivity was confirmed using indirect ELISA. The first pair and full-strip pair tests were performed to select the optimal candidate clones, and a rapid diagnosis kit with excellent reactivity was developed by applying these to a rapid diagnosis kit based on gold conjugates. Conclusions: The development of this rapid diagnosis kit with excellent performance in congestive heart failure is expected to improve disease management by providing an early assessment of the risk of heart failure.

Background: Candida albicans is an yeast species that colonizes the vaginal and oral mucosa of healthy women. However, it exhibits pathogenicity when the balance between yeast and mucous membranes and host defense mechanisms is disrupted. Objectives: To develop an auxiliary treatment for vaginitis, we evaluated the inhibitory effects of a probiotic bacterial strain isolated from kimchi on C. albicans. Methods: Lactobacillus plantarum, which exhibits potent inhibitory activity against pathogenic bacteria and is resistant to broad-spectrum antibiotics, was isolated from commercially kimchi in Korea, and its antagonistic effects on C. albicans were examined in a mixed culture with ME-180 cervical carcinoma cells. Results: Candida albicans caused extensive damage in ME-180 cells. In ME-180 cells inoculated with L. plantarum and then with C. albicans, the extent of cell damage increased as the concentration of the C. albicans culture increased. However, in ME-180 cells inoculated with L. plantarum at 106 CFU/mL or at a higher concentration, the extent of cell damage increased substantially with the concentration of C. albicans, indicating that L. plantarum inhibited the growth of C. albicans. Conclusions: Lactobacillus plantarum did not directly inhibit the growth of C. albicans but may have inhibited biofilm development at an early stage, thereby preventing the growth and mucosal adhesion of C. albicans. Further investigation of the safety, side effects, and metabolism of L. plantarum and its potential infectivity in animals is required before the L. plantarum isolate can be used to treat vaginitis.

Although tuberculosis burden is generally declining, the relative importance of nontuberculous mycobacteria (NTM) is increasing. In South Korea, few studies have evaluated Mycobacterium tuberculosis complex (MTBC) and NTM detection patterns and species distribution using long-term data. We retrospectively compared MTBC and NTM detection patterns using respiratory specimen-based laboratory data from a tertiary care hospital in South Korea (2016–2025). We analyzed 48,533 specimens, and the sum of annual patient counts after within-year deduplication was 30,275. Patient-level positivity decreased for MTBC (4.7% to 2.4%) but increased for NTM (7.7% to 10.3%), with corresponding changes at the specimen level. Age- and sex-adjusted annual odds ratios (95% confidence intervals) were 0.913 (0.892–0.934) for MTBC and 1.009 (0.994–1.023) for NTM; the overall linear NTM trend was nonsignificant. NTM-positive patients were older than MTBC-positive patients (median, 73 vs. 64 years). Co-detection of MTBC–NTM or multiple NTM species or subspecies was also observed. MTBC positivity declined, whereas NTM positivity increased mainly during 2016–2019; the relative proportion of NTM detections increased. Co-detection in the same specimen suggests the importance of differentiating MTBC from NTM and identifying NTM. Our findings may inform the development of institutional laboratory diagnostic strategies.