Cheong HS, et al. Infect Chemother. 2022 Dec;54(4):637-673. https://doi.org/10.3947/ic.2022.0171

Park SY, et al. Infect Chemother. 2024 Aug;56:e35. https://doi.org/10.3947/ic.2024.0038

The incidence of Proteus mirabilis antimicrobial resistance, especially that mediated by extended-spectrum β-lactamases (ESBLs), has increased. We investigated the impact of ESBL production on the mortality of patients with P. mirabilis bacteremia in Korea. Patients diagnosed with P. mirabilis bacteremia between November 2005 and December 2013 at a 2000-bed tertiary care center in South Korea were included in this study. Phenotypic and molecular analyses were performed to assess ESBL expression. Characteristics and treatment outcomes were investigated among ESBL-producing and non-ESBL-producing P. mirabilis bacteremia groups. A multivariate analysis of 28-day mortality rates was performed to evaluate the independent impact of ESBLs. Among 62 P. mirabilis isolates from 62 patients, 14 expressed ESBLs (CTX-M, 2; TEM, 5; both, 6; other, 1), and the 28-day mortality rate of the 62 patients was 17.74%. No clinical factor was significantly associated with ESBL production. The 28-day mortality rate in the ESBL-producing group was significantly higher than that in the non-ESBL-producing group (50% vs. 8.3%, p = 0.001). A multivariate analysis showed that ESBL production (odds ratio [OR], 11.53, 95% confidence interval [CI], 2.11–63.05, p = 0.005) was independently associated with the 28-day mortality rate in patients with P. mirabilis bacteremia. ESBL production is significantly associated with mortality in patients with bacteremia caused by P. mirabilis. Rapid detection of ESBL expression and prompt appropriate antimicrobial therapy are required to reduce mortality caused by P. mirabilis bacteremia.

Omicron variant viruses spread rapidly, even in individuals with high vaccination rates. This study aimed to determine the utility of the antibody against spike protein level as a predictor of the disease course of coronavirus disease 2019 (COVID-19) in vaccinated patients. Between December 11, 2021, and February 10, 2022, we performed a prospective observational cohort study in South Korea, which included patients infected with Delta and Omicron variants. A multivariable logistic regression analysis to determine the association between antibody levels and outcomes was conducted. The relationship between antibody levels and cycle threshold (Ct) values was confirmed using a generalized linear model. From 106 vaccinated patients (39 Delta and 67 Omicron), the geometric mean titers of antibodies in patients with fever (≥37.5°C), hypoxia (≤94% of SpO₂), pneumonia, C-reactive protein (CRP) elevation (>8 mg/L), or lymphopenia (<1100 cells/μL) were 1201.5 U/mL, 98.8 U/mL, 774.1 U/mL, 1335.1 U/mL, and 1032.2 U/mL, respectively. Increased antibody levels were associated with a decrease in the occurrence of fever (adjusted odds ratio [aOR], 0.23; 95% CI, 0.12–0.51), hypoxia (aOR, 0.23; 95% CI, 0.08–0.7), CRP elevation (aOR, 0.52; 95% CI, 0.29–0.0.94), and lymphopenia (aOR, 0.57; 95% CI, 0.33–0.98). Ct values showed a positive correlation between antibody levels (P = .02). Antibody levels are predictive of the clinical course of COVID-19 in vaccinated patients with Delta and Omicron variant infections. Our data highlight the need for concentrated efforts to monitor patients with severe acute respiratory syndrome coronavirus 2 infection who are at risk of low antibody levels.

Despite the low measles antibody positivity rate among young healthcare workers (HCWs) who have previously received two doses of a measles-containing vaccine (MCV), whether an additional dose of MCV acts as a booster remains unknown. Thus, we aimed to evaluate the immune responses to a third dose of MCV in young HCWs. Hospital-wide measles seroprevalence was assessed using enzyme-linked immunosorbent assay (ELISA). The immunogenicity of a third dose of MCV was determined in young seronegative HCWs (born between 1986 and 1997) who had previously received a two-dose measles vaccination. A total of 3033 (92.6%) HCWs had anti-measles immunoglobulin G. The lowest seropositivity rate was observed in HCWs aged 20-24 years (87.7%). In this group, HCWs who received a third dose of MCV had higher seropositivity than those who received a second dose (89.5% vs. 75.4%). A third dose of MCV was administered to 18 HCWs who did not have anti-measles IgG despite two doses. Neutralizing antibody titers increased significantly 4 weeks after the third vaccination. Although neutralizing antibody titers decreased 1 year post vaccination, 17 (94.4%) HCWs had medium (121-900 mIU/mL) or high (>900 mIU/mL) levels. Furthermore, the third dose of MCV increased the measles virus-specific T-cell effector function. The third dose of MCV induced a strong immune response against measles in young seronegative HCWs who had previously received a two-dose measles vaccination.

Objective: To evaluate the effect of female sex hormones on the clinical outcomes of coronavirus disease 2019 patients using national claims data. Methods: This retrospective cohort study used the Health Insurance Review and Assessment data of 5,061 adult patients with laboratory-confirmed coronavirus disease 2019 in South Korea from January 20 to April 8, 2020. To evaluate the effect of hormone therapy on clinical outcomes among women, subgroup analyses using age-matched case-control data were performed. Results: Coronavirus disease 2019 was most prevalent in women in the 20-39 years age group (1,250 [44.14%]). Men were more likely to receive oxygen therapy (144 [6.46%] vs 131 [4.63%], P = 0.004), be admitted to the intensive care unit (60 [2.69%] vs 53 [1.87%], P = 0.049), and have a longer length of stay after admission to the intensive care unit (19.70 ± 11.80 vs 14.75 ± 9.23, P = 0.016). However, there was no significant difference in the mortality rate (men vs women: 42 [1.88%] vs 42 [1.48%], P = 0.267). In the multivariable Cox analysis, older age and underlying comorbidities, but not sex, were independent risk factors for mortality. Hormone therapy was not significantly associated with clinical outcomes. Conclusions: This study, using nationwide data, suggests that female sex hormones are not associated with the morbidity and clinical outcomes of coronavirus disease 2019 in South Korea.