Tixagevimab/cilgavimab is a monoclonal antibody used to prevent coronavirus disease 2019 among immunocompromised hosts and maintained neutralizing activity against early omicron variants. Omicron BN.1 became a dominant circulating strain in Korea early 2023, but its susceptibility to tixagevimab/cilgavimab is unclear. We conducted plaque reduction neutralization test (PRNT) against BN.1 in a prospective cohort (14 patients and 30 specimens). BN.1 PRNT was conducted for one- and three-months after tixagevimab/ cilgavimab administration and the average PRNT ND 50 of each point was lower than the positive cut-off value of 20 (12.9 ± 4.5 and 13.2 ± 4.2, respectively, P = 0.825). In the paired analyses, tixagevimab/cilgavimab-administered sera could not actively neutralize BN.1 (PRNT ND 50 11.5 ± 2.9, P = 0.001), compared with the reserved activity against BA.5 (ND 50 310.5 ± 180.4). Unlike virus-like particle assay, tixagevimab/cilgavimab was not active against BN.1 in neutralizing assay, and would not be effective in the present predominance of BA.2.75 sublineages.

As nucleocapsid protein of severe acute respiratory syndrome coronavirus 2 is immunogenic but not targeted in vaccines, it could be useful in distinguishing natural infection from vaccination. We aimed to investigate the clinical utility of sero-immunological responses against the nucleocapsid protein. Nucleocapsid antibody immunoassay study with 302 coronavirus disease 2019 (COVID-19) patients showed lower titers in immunocompromised patients (P < 0.001), higher titers in higher severity (P = 0.031), and different seroconversion rates and titers according to variants of concern. Longitudinal evaluation of nucleocapsid antibodies using 513 samples from 291 COVID-19 patients revealed that it could persist up to 556 days from symptom onset. Interferon gamma release assay against the nucleocapsid protein showed poor response, precluding the deduction of a cut-off for the nucleocapsid protein. In conclusion, nucleocapsid antibody provides instructive clues about the immunogenicity of nucleocapsid proteins by different seroconversion rates and titers according to the severity of infection, host immune status, and different variants of concern.

Background/Aims: The coronavirus disease 2019 (COVID-19) pandemic has accelerated digital transformation (DT). We investigated the trend of the public interest in technologies regarding the DT and Koreans’ experiences and their perceptions of the future impact of these technologies. Methods: Using Google Trends, the relative search volume (RSV) for topics including “coronavirus,” “artificial intelligence,” “cloud,” “big data,” and “metaverse” were retrieved for the period from January 2020 to January 2022. A survey was conducted to assess the population’s knowledge, experience, and perceptions regarding the DT. Results: The RSV for “metaverse” showed an increasing trend, in contrast to those for “cloud,” “big data,” and “coronavirus.” The RSVs for DT-related keywords had a negative correlation with the number of new weekly COVID-19 cases. In our survey, 78.1% responded that the positive impact of the DT on future lives would outweigh the negative impact. The predictors for this positive perception included experiences with the metaverse (4.0-fold) and virtual reality (VR)/augmented reality (AR) education (3.8-fold). Respondents predicted that the biggest change would occur in the healthcare sector after transportation/ communication. Conclusions Koreans’ search interest for “metaverse” showed an increasing trend during the COVID-19 pandemic. Koreans believe that DT will bring about big changes in the healthcare sector. Most of the survey respondents have a positive outlook about the impact of DT on future life, and the predictors for this positive perception include the experiences with the metaverse or VR/AR education. Healthcare professionals need to accelerate the adoption of DT in clinical practice, education and training.

Purpose: Real-world experience with tocilizumab in combination with dexamethasone in patients with severe coronavirus disease (COVID-19) needs to be investigated. Materials and Methods: A retrospective cohort study was conducted to evaluate the effect of severity-adjusted dosing of dexamethasone in combination with tocilizumab for severe COVID-19 from August 2020 to August 2021. The primary endpoint was 30-day clinical recovery, which was defined as no oxygen requirement or referral after recovery. Results: A total of 66 patients were evaluated, including 33 patients in the dexamethasone (Dexa) group and 33 patients in the dexamethasone plus tocilizumab (DexaToci) group. The DexaToci group showed a statistically significant benefit in 30-day clinical recovery, compared to the Dexa group (p=0.024). In multivariable analyses, peak FiO2 within 3 days and tocilizumab combination were consistently significant for 30-day recovery (all p<0.05). The DexaToci group showed a significantly steeper decrease in FiO2 (-4.2±2.6) than the Dexa group (−2.7±2.6; p=0.021) by hospital day 15. The duration of oxygen requirement was significantly shorter in the DexaToci group than the Dexa group (median, 10.0 days vs. 17.0 days; p=0.006). Infectious complications and cellular and humoral immune responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the convalescence stage were not different between the two groups. Conclusion A combination of severity-adjusted dexamethasone and tocilizumab for the treatment of severe COVID-19 improved clinical recovery without increasing infectious complications or hindering the immune response against SARS-CoV-2.

No abstract available.
Gastrointestinal Microbiome ; Klebsiella pneumoniae ; Klebsiella ; Liver Abscess ; Liver

Background/Aims: Healthcare-associated (HCA) infection is a recently suggested new category of community-onset infections. The implications of HCA infections in terms of diagnosis, treatment, and outcomes of spontaneous bacterial peritonitis (SBP) are not well understood. We sought to delineate the differences between community-acquired (CA) SBP and HCA SBP with specific interest in the antimicrobial resistance of causative microorganisms and outcomes. Methods: We conducted a retrospective cohort study of all SBP episodes with positive ascitic culture and/or blood culture from June 2000 to August 2011. Community-onset SBP episodes were included when they occurred within 48 hours after admission and were classified as CA SBP and HCA SBP based on the predefined criteria. Results: A total of 188 episodes of community-onset SBP were analyzed (65.4% HCA SBP and 34.6% CA SBP). HCA SBP had a higher resistance rate to third-generation cephalosporin (6.8% vs. 1.6%, p = 0.168). The overall 30-day mortality was similar between both groups (37.4% vs. 41.5%, p = 0.638). The independent risk factors for 30-day all-cause mortality in community-onset SBP included high Child-Pugh score, acute kidney injury, and resistance to third-generation cephalosporins; HCA infection was not associated. Conclusions Hepatic functional status, renal dysfunction, and third-generation cephalosporin resistant pathogens more adversely affected the outcome of cirrhotic patients with community-onset SBP rather than HCA infection. The higher rate of third-generation cephalosporin resistance was notable in HCA SBP, which will require a novel approach to empirical antibiotic treatment selection in this population.

Background: Cancer patients can be at a higher risk of infection due to drug-resistant bacteria than the general population for various reasons. We performed a retrospective study to evaluate possible risk factors and outcomes of extended-spectrum beta-lactamaseproducing Klebsiella pneumoniae (ESBL-KP) bacteremia in cancer patients. Materials and Methods: Cases were divided into two groups based on whether or not the isolated strain produced ESBL and multivariable regressions were done to identify possible risk factors of ESBL-KP bacteremia and mortality. For ESBL-producing strain, additional molecular analysis was done. Results: 278 cases with KP bacteremia were identified between 2010 and 2012, of which ESBLproducers were 50 (18%). The presence of percutaneous drainage catheter [odds ratio (OR) 4.99, P <0.001] and prior exposure to certain classes of antibiotics including third-generation cephalosporin (OR 2.14, P = 0.03) had significant associations with ESBL-KP bacteremia. Individuals who died within 14 days after the onset of KP bacteremia were more likely to have higher mean Pitt bacteremia score (1.56 in survival group vs. 3.43 in mortality group, P <0.001), hemodialysis (OR 17.03, P = 0.01) and chronic liver disease (OR 5.57, P = 0.01). Although 14-day mortality was higher with ESBL production (OR 2.76, P = 0.04), no significant differences in 30-day mortality (OR 1.67, P = 0.20) and other morbidity indices were observed. 49 ESBL-KP isolates, 65.4% of them produced CTX-M-14 and CTX-M-15 enzymes, and ST711 was the most common. Conclusion There were several differences in clinical characteristics between ESBL-KP and nonESBL-KP bacteremia in cancer patients, similar to previous reports including non-cancer patients.

Coronavirus disease 2019 (COVID-19) outbreak is spreading rapidly all over the world, being a major threat to public health. Since clinical feature of COVID-19 has not been fully evaluated yet, empirical antibacterial agents are frequently combined for the treatment of COVID-19 in addition to antiviral agents, concerning co-existing bacterial pathogens. We experienced a case of severe thrombocytopenia with epistaxis and petechiae, while treating a COVID-19 patient with ceftriaxone, levofloxacin, and lopinavir/ritonavir. The platelet count decreased to 2,000/mm 3 and recovered after discontinuation of the three suspected drugs. In treating a potentially fatal emerging infectious disease, empirical and/or experimental approach would be unavoidable. However, the present case suggests that the possibility of adverse effects caused by polypharmacy should also be carefully considered.

Purpose: Epstein-Barr virus (EBV) infection is related to infectious mononucleosis or nasopharyngeal cancer, and its epidemiology may change according to the socioeconomic development of communities. This study aimed to evaluate the recent epidemiology of EBV seropositive rate in Korea. Methods: We retrospectively reviewed EBV serology test results obtained from a part of clinical care at Samsung Medical Center, Seoul, South Korea, from January 2000 to December 2017. Results: The EBV seropositive rate in 26,527 subjects during the study period was 81.0% (21,485/26,527): 44.4% (2,716/6,122) in subjects aged 0–9 years, 75.8% (2,077/2,739) in those aged 10–19 years, and 94.5% (16,692/17,666) in those aged ≥20 years. The EBV seropositive rate decreased from 89.4% (8,592/9,616) in 2000–2008 to 76.2% (12,893/16,911) in 2009– 2017 (P<0.001). Especially, the EBV seropositive rate in subjects aged 0–19 years significantly decreased from 2000–2008 to 2009–2017 (0–9 years, 62.8% [1,172/1,866] in 2000–2008 and 36.3% [1,544/4,256] in 2009–2017; 10–19 years, 83.8% [745/858] in 2000–2008 and 70.8% (1,332/1,881) in 2009–2017) (P<0.001). Conclusions The EBV seropositive rate in children has decreased in the last 20 years. As the age of patients with primary EBV infection increased, there is a need for interest in clinical manifestation, such as infectious mononucleosis, in adolescents and young adults.

As 16S ribosomal RNA (rRNA)-targeted sequencing can detect DNA from non-viable bacteria, it can be used to identify pathogens from clinical samples even in patients pretreated with antibiotics. We compared the results of 16S rRNA-targeted sequencing and culture for identifying bacterial species in normally sterile body fluid (NSBF): cerebrospinal, pericardial, peritoneal and pleural fluids. Over a 10-year period, a total of 312 NSBF samples were evaluated simultaneously using 16S rRNA-targeted sequencing and culture. Results were concordant in 287/312 (92.0%) samples, including 277 (88.8%) negative and 10 (3.2%) positive samples. Of the 16 sequencing-positive, culture-negative samples, eight showed clinically relevant isolates that included Fusobacterium nucleatum subsp. nucleatum, Streptococcus pneumoniae, and Staphylococcus spp. All these samples were obtained from the patients pretreated with antibiotics. The diagnostic yield of 16S rRNA-targeted sequencing combined with culture was 11.2%, while that of culture alone was 6.1%. 16S rRNA-targeted sequencing in conjunction with culture could be useful for identifying bacteria in NSBF samples, especially when patients have been pretreated with antibiotics and when anaerobic infection is suspected.