Seroprevalence of SARS-CoV-2 antibodies in the community based on participants in the 2020 Korea National Health and Nutrition Examination Survey.

OBJECTIVES: The Korea National Health and Nutrition Examination Survey (KNHANES) is a nationwide cross-sectional surveillance system that assesses the health and nutritional status of the Korean population. To evaluate the occurrence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the community, we investigated the prevalence of anti-SARS-CoV-2 antibodies in the sera of KNHANES participants. METHODS: Subjects were recruited between April 24 and December 12, 2020. In total, 5,284 subjects aged 10-90 years from 17 regions participated. SARS-CoV-2 antibodies were screened using the Elecsys Anti-SARS-CoV-2 assay. Positive samples were verified using 4 different SARS-CoV-2 antibody assays and the plaque reduction neutralizing test. The final seropositivity criteria were a positive screening test and at least 1 positive result from the 5 additional tests. RESULTS: Almost half (49.2%; 2,600/5,284) of participants were from metropolitan areas, 48.9% were middle-aged (40-69 years), and 20.5% were in their 20s or younger. The seropositivity rate was 0.09% (5/5,284). Three of the 5 antibody-positive subjects had a history of infection, of whom 2 were infected abroad and 1 was infected in a local cluster outbreak. CONCLUSIONS: The low SARS-CoV-2 antibody seroprevalence in Korea indicates that there have been few coronavirus disease 2019 (COVID-19) cases due to successful COVID-19 management measures (e.g., diagnostic tests for overseas arrivals, national social distancing, and strict quarantine measures). Moreover, asymptomatic infections were uncommon due to active polymerase chain reaction testing. However, hidden infections may exist in the community, requiring the continuation of quarantine and vaccination measures.

Characterization and validation of an alternative reference bacterium Korean Pharmacopoeia Staphylococcus aureus strain.

The National Culture Collection of Pathogens (NCCP) is a microbial resource bank in Korea that collects pathogen resources causing infectious disease in human and distributes them for research and education. The NCCP bank attempts to discover strains with various characteristics and specific purposes to provide diverse resources to researchers. Staphylococcus aureus American Type Culture Collection (ATCC) 6538P is used as a reference strain in the microbial assay for antibiotics in the Korean and in the United States Pharmacopoeias. We aimed to analyze domestically isolated microbial resources from the NCCP to replace the S. aureus reference strain. Staphylococcus aureus strains were identified using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and the VITEK-2 system and characterized by multilocus sequence typing, 16S rRNA sequencing, and antibiotic susceptibility testing. Several candidate strains had similar characteristics as the reference strain. Among them, the nucleotide sequence of the 16S rRNA region of NCCP 16830 was 100% identical to that of the reference strain; it was sensitive to six types of antibiotics and showed results most similar to the reference strain. A validity evaluation was conducted using the cylinder-plate method. NCCP 16830 presented valid results and had the same performance as ATCC 6538P; therefore, it was selected as an alternative candidate strain.

Evaluation of global evolutionary variations in the early stage of SARS-CoV-2 pandemic.

To understand the origin of variants and their evolutionary history in the early stage of the COVID-19 pandemic, time-scaled phylogenetic and gene variation analyses were performed. The mutation patterns and evolution characteristics were examined using the Bayesian Evolutionary Analysis Sampling Trees (BEAST) with 349 whole-genome sequences available by March 2020. The results revealed five phylogenetic clusters (Groups A-E), with 408 nucleotide variants. The mutations including the deletion of three nucleotides underwent various and complicated changes in the whole genome over time, while some frequency or transient mutations were also observed. Phylogenetic analysis demonstrated that SARS-CoV-2 originated from China and was transmitted to other Asian countries, followed by North America and Europe. This study could help to comprehensively understand the evolutionary characteristics of SARS-CoV-2 with a special emphasis on its global variation patterns.

Cohnella cholangitidis sp. nov., a novel species of the genus Cohnella isolated from a clinical specimen in Korea.

A Gram-positive, aerobic, rod-shaped bacterium, designated as strain 1605-214T, was isolated from the blood sample of a patient with cholangitis. Based on its 16S rRNA gene sequence, the strain 1605-214T belonged to the genus Cohnella and exhibited 97.9% sequence identity with Cohnella luojiensis DSM 24270T (GQ214052). DNA-DNA hybridization, digital DNA-DNA hybridization, and average nucleotide identity values between the two species were 23% ± 1.9, 21.1%, and 77.2%, respectively. The cellular fatty acids of strain 1605-214T were mainly comprised of anteiso-C15:0 (36.1%), iso-C16:0 (16.5%), and C16:0 (15.1%). The predominant quinone was menaquinone-7; predominant polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, and aminophospholipid-1. The cell wall peptidoglycan of strain 1605-214T contained meso-diaminopimelic acid. DNA G + C content of strain 1605-214T was 50.6 mol%. 5187 genes out of a total of 5413 (94.6%) were assigned putative functions using eggNOG v5.0. Based on genotypic characteristics and genomic sequence analysis results, strain 1605-214T was confirmed to represent a novel species of genus Cohnella, for which the name Cohnella cholangitidis sp. nov., was proposed.

Distribution of Pathogen Resources by the National Culture Collection for Pathogens in South Korea from 2015 to 2019.

Introduction: The National Culture Collection for Pathogens (NCCP) in the Korea Disease Control and Prevention Agency (KDCA) is in charge of the collection, quality control, and commercialization of pathogens and of information on pathogens that cause infectious diseases, and distributes them to be utilized for promoting public health and the health care industry. Since the NCCP Task Force was established in 2009 and the law for collection, management, and exploitation of pathogen resources became effective in 2017, NCCP has been responsible for the deposition, registration, and preservation of pathogen resources. Herein, we provide information on the recent status of pathogen resource distribution over the past 5 years and pathogen resources that are available for distribution presently. Results: Within the past 5 years, the numbers of pathogen resources distributed were 1659, 1823, 1457, 1156, and 1706 in the years 2015, 2016, 2017, 2018, and 2019, respectively. In addition, more pathogens were distributed in February, March, September, and October than in other months. When categorized by the type of institution, profit organizations (3069) requested more pathogen resources than national and public research institutes (2291). Furthermore, based on the purpose of distribution, 440 cases were for vaccine or therapeutic development, 3041 for diagnostic technology development, 2487 for education, and 1134 for quality control. Conclusion: Based on these findings, we publicized the information on the distribution of pathogen resources to encourage their widespread use in infectious disease research and public health.

Complete Genome Sequences of Micrococcus luteus Strains NCCP 15687 and NCCP 16831, Isolated in South Korea.

In this study, the complete genome sequences of Micrococcus luteus strains NCCP 15687 and NCCP 16831 were determined and deposited in the National Culture Collection for Pathogens (NCCP) of South Korea. Genomic DNA was isolated from blood samples from patients infected with M. luteus.

Serious Adverse Transfusion Reactions Reported in the National Recipient-Triggered Trace Back System in Korea (2006-2014).

BACKGROUND: Adverse transfusion reactions (ATRs) are clinically relevant to patients with significant morbidity and mortality. This study aimed to review the cases of ATR reported in the recipient-triggered trace back system for a recent nine-year period in Korea. METHODS: Nine-year data obtained from 2006 to 2014 by the trace back system at the Division of Human Blood Safety Surveillance of the Korean Centers for Disease Control (KCDC) were reviewed. The suspected cases were assessed according to six categories: (i) related to, (ii) probably related to, (iii) probably not related to, (iv) not related to transfusion, (v) unable to investigate, and (vi) under investigation. RESULTS: Since 2006, 199 suspected serious ATRs were reported in hospitals and medical institutions in Korea, and these ATRs were reassessed by the division of Human Blood Safety Surveillance of the KCDC. Among the reported 193 cases as transfusion related infections, hepatitis C virus (HCV) infection (135, 67.8%) was reported most frequently, followed by hepatitis B virus (HBV) infection (27, 13.6%), HIV infection (13, 6.5%), syphilis (9, 4.5%), malarial infection (4, 2.0%), other bacterial infections (3, 1.5%), HTLV infection (1, 0.5%), and scrub typhus infection (1, 0.5%), respectively. Of the 199 cases, 13 (6.5%) cases were confirmed as transfusion-related (3 HCV infections, 3 malarial infections, 1 HBV infection, 2 Staphylococcus aureus sepsis, 3 transfusion-related acute lung injuries, and 1 hemolytic transfusion reaction). CONCLUSIONS: This is the first nationwide data regarding serious ATRs in Korea and could contribute to the implementation of an effective hemovigilance system.

Genotyping of 22 blood group antigen polymorphisms and establishing a national recipient registry in the Korean population.

It is often difficult for standard blood banks in Korea to supply adequate amounts of blood for patients with rare phenotype. Moreover, the definition of a blood in need is ambiguous, and much remains to be learned. In this study, we determined the prevalence of various red blood cell (RBC) antigens from a donor viewpoint and estimated the demand for specific antigen-negative blood from a patient viewpoint. Our data will aid the establishment of a Rare Blood Program in Korea (KRBP). RBC genotyping of 419 blood donors was performed using a Lifecodes RBC/RBC-R typing kit (Immucor, Norcross, GA). A national recipient registry website has been established. Each hospital-based blood bank voluntarily enters data on antibodies detected and identified and the outcomes of specific antigen testing. We calculated the availabilities of specific antigen-negative blood components based on these registry data and predicted the prevalence of RBC antigens via RBC genotyping. The prevalences of various RBC antigens in the D-negative population were determined for the first time, and the Cartwright, Scianna, Dombrock, Colton, Landsteiner-Wiener, Cromer, and Knops blood group systems were identified. The availabilities of specific antigen-negative units differed when calculations were based on serotyping or genotyping, especially in the D-negative group. Data on the prevalences of various blood antigens are essential for estimating the availabilities of blood components that are appropriate for use by patients expressing relevant antibodies. Then, blood banks would be able to efficiently supply safe blood products.

Lon Mutant of Brucella abortus Induces Tumor Necrosis Factor-Alpha in Murine J774.A1 Macrophage.

OBJECTIVES: The objective of this study was to isolate a Brucella lon mutant and to analyze the cytokine response of B. lon mutant during macrophage infection. METHODS: A wild-type Brucella abortus strain was mutagenized by Tn5 transposition. From the mouse macrophage J774.A1 cells, total RNA was isolated at 0 hours, 6 hours, 12 hours, and 24 hours after infection with Brucella. Using mouse cytokine microarrays, we measured transcriptional levels of the cytokine response, and validated our results with a reverse transcriptase-polymerase chain reaction (RT-PCR) assay to confirm the induction of cytokine messenger RNA (mRNA). RESULTS: In host J774.A1 macrophages, mRNA levels of T helper 1 (Th1)-type cytokines, including tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), interleukin-2 (IL-2), and IL-3, were significantly higher in the lon mutant compared to wild-type Brucella and the negative control. TNF-α levels in cell culture media were induced as high as 2 µg/mL after infection with the lon mutant, a greater than sixfold change. CONCLUSION: In order to understand the role of the lon protein in virulence, we identified and characterized a novel B. lon mutant. We compared the immune response it generates to the wild-type Brucella response in a mouse macrophage cell line. We demonstrated that the B. lon mutants induce TNF-α expression from the host J774.A1 macrophage.

Cervical lymphadenitis in a patient coinfected with Toxoplasma gondii and Bartonella henselae.

Cat scratch disease, caused by Bartonella henselae, is a worldwide zoonosis that is most frequently associated with the bite or scratch of a kitten under 6 months of age, as well as from a fleabite. Toxoplsma gondii is also another important zoonotic agent in cats and humans, which is mainly acquired by ingestion of food or water that is contaminated with oocytes shed by cats or by eating undercooked or raw meat containing tissue cysts. Here, we report a first case of young patient with cervical lymphadenitis, which shows serological and histological evidence of B. henselae and T. gondii coinfection in Korea with literature review.

[Seroprevalence and risk factors of brucellosis among slaughterhouse workers in Korea].

OBJECTIVES: The incidence of zoonoses in Korea has increased recently. However, the study of high risk groups for zoonoses has not been conducted to date in Korea. Thus, we did this study to obtain data on brucellosis among slaughterhouse workers in Korea. METHODS: We evaluated the structure of slaughterhouses and the process of slaughtering by reviewing the relevant literature and doing field studies. We visited 73 slaughterhouses and 62 residual products handle houses across the country. In addition, we conducted a questionnaire survey of the work activities, and obtained blood samples in order to determine the seroprevalence and risk factors of brucellosis. The titers of brucellosis antibodies were measured using the standard tube agglutination test (SAT). We diagnosed subjects as seropositive for Brucellosis if the titers were more than 1:160. The data collected was evaluated using SPSS ver. 17.0. RESULTS: We included 1,503 subjects and obtained 1,482 blood samples among them: 849 workers involved in slaughtering, 351 handlers of residual products, 190 inspectors and their assistants, and 92 grading testers and their assistants. The seroprevalence of brucellosis among the slaughterhouse workers was 0.8% (95% CI=0.4-1.5). Broken down, the seroprevalence of brucellosis among the workers involved in slaughtering was 0.7% (95% CI=0.3-1.6), the handlers of residual products was 1.7% (95% CI=0.7-3.9) respectively. Risk factors for contracting brucellosis among slaughterhouse workers were being splashed with cattle blood around the mouth, cattle secretions around the body and not putting on protective apron while at work. CONCLUSIONS: An educational program is needed for high risk groups on zoonoses about the prevention of infection. Thus, effective working guidelines for workers who participate in the slaughter of animals must be developed in order to protect them from zoonoses.

Brucella endocarditis with splenic abscess: a report of the first case diagnosed in Korea.

Human brucellosis has a broad spectrum of clinical manifestations, which includes endocarditis, a focal complication that is uncommon yet responsible for the majority of associated deaths. The most successful treatment outcomes of Brucella endocarditis have been reported with usage of both antimicrobial agents and surgery. However, there are few reports on the treatment of Brucella endocarditis using antibiotics only. We report the first case in Korea of Brucella endocarditis with aortic valve vegetations and an accompanying splenic abscess, which were treated successfully with antibiotic therapy alone.

Cytokine response in Balb/c mice infected with Francisella tularensis LVS and the Pohang isolate.

We investigated the immune response induced by the Francisella (F.) tularensis live vaccine strain (LVS) and the Pohang isolate. After the Balb/c mice were infected intradermally (i.d) with 2 x 10(4) cfu of F. tularensis LVS and Pohang, respectively, their blood and organs were collected at different times; 0, 3, 6, 24, 72, 96, 120 and 168 h after infection. Using these samples, RT-PCR and ELISA analysis were carried out for the comparative study of the cytokines, including TNF-alpha, INF-gamma, IL-2, IL-4, IL-10 and IL-12. In the Pohang-infected mice at 120 h, the liver showed a 53 times higher level of TNF-alpha and a 42 times higher level of IFN-gamma than the respective levels at the early time points after infection. The levels of TNF-alpha and IFN-gamma induced by LVS were 5 times lower than those induced by the Pohang isolate. Also, the organs from the Pohang-infected mice showed higher levels of TNF-alpha, IFN-gamma, IL-10 and IL-12 than the levels in the LVS-infected mice. The blood from the Pohang-infected mice at 120 h revealed about a 40 times increased level of IFN-gamma, and IL-10 was also increased by 4 times at 96 h compared to an early infection time point, while IL-4 was not induced during the whole infection period. These results suggest that F. tularensis may induce a Th1-mediated immune response to in vivo infection and the Pohang isolate has a higher capacity than the LVS to induce an acute immune response in Blab/c mice.

Clinical Characteristics of Human Brucellosis in South Korea / 감염과화학요법

BACKGROUND: Since the first Korean case of human brucellosis was reported in 2002, the incidence of human brucellosis has been rapidly increasing. We performed this study to evaluate the clinical characteristics of human brucellosis occurring in South Korea. MATERIALS AND METHODS: Demographic features, clinical manifestations, and therapeutic outcomes of cases confirmed as brucellosis according to WHO diagnostic criteria were evaluated. Species of Brucella isolates were identified with 16S rRNA gene sequencing method. Serologic diagnosis was performed with standard tube agglutination test (STA). RESULTS: A total of 34 cases were enrolled from 2003 to 2006 in six hospitals. Eight cases were confirmed with the isolation of Brucella from blood and 26 cases were confirmed with titer of antibodies < or =1:160 by STA. Male (31) was predominant and most of the patients were cattle farmers. The most common transmission route was direct contact with infected or their cattle byproducts. Fever was the most prominent symptom and fatigue followed. Gastrointestinal and musculoskeletal systems were commonly complicated. Patients were treated with doxycycline and rifampin or aminoglycosides for more than 6 weeks. All patients responded well to the therapeutic regimens, but one patient relapsed 10 months after treatment. CONCLUSION: Brucellosis occurring in Korea has been caused by B. abortus, whose preferred natural host animals are cattle. Korean patients were infected through direct contact with bovine brucellosis. Clinical manifestations of brucellosis were similar to those occurring worldwide. Therapeutic outcomes were good among patients with brucellosis in Korea. In order to prevent human brucellosis, measures to eradicate bovine brucellosis should precede.

Clinical Characteristics of Human Brucellosis in South Korea / 감염과화학요법

BACKGROUND: Since the first Korean case of human brucellosis was reported in 2002, the incidence of human brucellosis has been rapidly increasing. We performed this study to evaluate the clinical characteristics of human brucellosis occurring in South Korea. MATERIALS AND METHODS: Demographic features, clinical manifestations, and therapeutic outcomes of cases confirmed as brucellosis according to WHO diagnostic criteria were evaluated. Species of Brucella isolates were identified with 16S rRNA gene sequencing method. Serologic diagnosis was performed with standard tube agglutination test (STA). RESULTS: A total of 34 cases were enrolled from 2003 to 2006 in six hospitals. Eight cases were confirmed with the isolation of Brucella from blood and 26 cases were confirmed with titer of antibodies < or =1:160 by STA. Male (31) was predominant and most of the patients were cattle farmers. The most common transmission route was direct contact with infected or their cattle byproducts. Fever was the most prominent symptom and fatigue followed. Gastrointestinal and musculoskeletal systems were commonly complicated. Patients were treated with doxycycline and rifampin or aminoglycosides for more than 6 weeks. All patients responded well to the therapeutic regimens, but one patient relapsed 10 months after treatment. CONCLUSION: Brucellosis occurring in Korea has been caused by B. abortus, whose preferred natural host animals are cattle. Korean patients were infected through direct contact with bovine brucellosis. Clinical manifestations of brucellosis were similar to those occurring worldwide. Therapeutic outcomes were good among patients with brucellosis in Korea. In order to prevent human brucellosis, measures to eradicate bovine brucellosis should precede.

Analysis of cellular fatty acids in Orientia tsutsugamushi as taxonomic markers.

Six Orientia strains including 3 prototype strains such as Gilliam, Karp, and Kato, and 3 strains (Boryong, Pajoo, and Yongworl) isolated in Korea, were studied for the profiles of their cellular fatty acids. All tested strains contained octadecenoic acid C (18: 1) omega 9 c(57.3 +/- 3.5%), octadecanoic acid C (18: 0) (15.3 +/- 1.5%), and hexadecanoic acid C (16: 0) (12.7 +/- 1.7%) as major components; however, interestingly, eicosenoic acid C (20: 1) omega 9 c(2.6 +/- 0.6%) was found in all strains except the Yongworl strain. Furthermore none of the strains contained 3-hydroxy fatty acids. The ratios of total saturated fatty acid (SFA) to total unsaturated fatty acid (UFA) were within the range of 0.34 to 0.54. These results showed that the cellular fatty acid profile should provide more reliable information for the identification of these bacteria.