Seroprevalence and Risk Factors for Severe Fever with Thrombocytopenia Syndrome among the Korea National Park Service Workers / 農村醫學 地域保健

Objectives@#This study was carried out to understand the seroprevalence and risk factors for severe fever with thrombocytopenia syndrome (SFTS) among the Korea National Park Service (KNPS) workers. @*Methods@#We used the stored serum samples (763) and survey results collected from the previous investigation on scrub typhus and Lyme disease among the KNPS workers during 2016-2017. The serum samples were analyzed by double-antigen sandwich enzyme-linked immunosorbent assay, which was used to test the total antibody including IgG and IgM. @*Results@#The SFTS seroprevalence among the KNPS worrkers was 1.4%. In multivariate logistic analysis, the national park exploration programs (odds ratio, 3.48; 95% confidence interval, 1.01-12.01) was significantly associated with the seroprevalence of SFTS. @*Conclusion@#This study was the first serological study of SFTS among forestry workers in South Korea. Although the KNPS workers are at a high-risk group of SFTS, the prevention activities related to the working environment and habit was insufficient. Thus, systematic prevention education and training for the KNPS workers need to be strengthened.

Antibody Responses One Year after Mild SARS-CoV-2 Infection

Understanding the long-term kinetics of antibodies in coronavirus disease 2019 (COVID-19) is essential in interpreting serosurvey data. We investigated the antibody response one year after infection in 52 mildly symptomatic patients with severe acute respiratory syndromecoronavirus-2 (SARS-CoV-2) infection, using three commercial immunoassays and a surrogate virus neutralization test (sVNT) kit. Anti-N pan-immunoglobulin (Ig), anti-S IgG, and anti-S1 IgG were detected in 43 (82.7%), 44 (84.6%), and 30 (57.7%), respectively. In 49 (94.2%), the antibody could be detected by either anti-N pan-Ig or anti-S IgG assay. In the sVNT, 30 (57.7%) had positive neutralizing activity. Despite waning immunity, SARS-CoV-2 antibodies can be detected up to one year after infection, even in mild COVID-19 patients.

Antibody Responses One Year after Mild SARS-CoV-2 Infection

Understanding the long-term kinetics of antibodies in coronavirus disease 2019 (COVID-19) is essential in interpreting serosurvey data. We investigated the antibody response one year after infection in 52 mildly symptomatic patients with severe acute respiratory syndromecoronavirus-2 (SARS-CoV-2) infection, using three commercial immunoassays and a surrogate virus neutralization test (sVNT) kit. Anti-N pan-immunoglobulin (Ig), anti-S IgG, and anti-S1 IgG were detected in 43 (82.7%), 44 (84.6%), and 30 (57.7%), respectively. In 49 (94.2%), the antibody could be detected by either anti-N pan-Ig or anti-S IgG assay. In the sVNT, 30 (57.7%) had positive neutralizing activity. Despite waning immunity, SARS-CoV-2 antibodies can be detected up to one year after infection, even in mild COVID-19 patients.

Serotype Distribution and Antimicrobial Resistance of Invasive and Noninvasive Streptococcus pneumoniae Isolates in Korea between 2014 and 2016

BACKGROUND: Several factors contribute to differences in Streptococcus pneumoniae serotype distribution. We investigated the serotype distribution and antimicrobial resistance of S. pneumoniae isolated between 2014 and 2016 in Korea. METHODS: We collected a total of 1,855 S. pneumoniae isolates from 44 hospitals between May 2014 and May 2016, and analyzed the serotypes by sequential multiplex PCR. We investigated the distribution of each serotype by patient age, source of the clinical specimen, and antimicrobial resistance pattern. RESULTS: The most common serotypes were 11A (10.1%), followed by 19A (8.8%), 3 (8.5%), 34 (8.1%), 23A (7.3%), and 35B (6.2%). The major invasive serotypes were 3 (12.6%), 19A (7.8%), 34 (7.8%), 10A (6.8%), and 11A (6.8%). Serotypes 10A, 15B, 19A, and 12F were more common in patients ≤5 years old, while serotype 3 was more common in patients ≥65 years old compared with the other age groups. The coverage rates of pneumococcal conjugate vaccine (PCV)7, PCV10, PCV13, and pneumococcal polysaccharide vaccine 23 were 11.8%, 12.12%, 33.3%, and 53.6%, respectively. Of the 1,855 isolates, 857 (46.2%) were multi-drug resistant (MDR), with serotypes 11A and 19A predominant among the MDR strains. The resistance rates against penicillin, cefotaxime, and levofloxacin were 22.8%, 12.5%, and 9.4%, respectively. CONCLUSIONS: There were significant changes in the major S. pneumoniae serotypes in the community. Non-PCV13 serotypes increased in patients ≤5 years old following the introduction of national immunization programs with the 10- and 13-polyvalent vaccines.

Investigation of a Mumps Outbreak in a Dental Clinic at a University Hospital

BACKGROUND@#The Korean Society of Infectious Diseases recommends non-mandatory vaccination of newly employed healthcare workers (HCWs) with 2 measles–mumps–rubella (MMR) vaccine doses. Here, we aimed to investigate the seroprevalence of mumps among HCWs exposed to index patients with mumps and the efficacy of MMR vaccination as postexposure prophylaxis (PEP) when a mumps outbreak was encountered among HCWs in a tertiary university hospital in Korea.@*MATERIALS AND METHODS@#Four HCWs were diagnosed with mumps over a 4-day period in January 2016. Three were working at a dental clinic and one visited the clinic on the day of symptoms onset of the first patient. We investigated all HCWs who either worked in that dental clinic, visited the clinic, or being within 1.5 meter of the patients with mumps without wearing surgical masks. Seventy HCWs were exposed to 4 HCWs with mumps. We interviewed all the exposed HCWs to investigate mumps infection and MMR vaccination history; they were all tested for mumps IgG.@*RESULTS@#Of the 70 exposed HCWs, 56 (80%) were females; the median age was 34 years (range 21–59 years) and 3 had a history of mumps infection. The vaccination status verification of mumps among the HCWs was unavailable. As for serologic testing, 54 (77.1%) were seropositive. Seropositivity rate for the mumps virus in males was significantly lower than that in females (50.0% vs. 83.9% respectively, P = 0.007). A lower seroprevalence of mumps was observed among HCWs aged ≥40 years than those aged 2 days. Thirty-four (62.9%) of 54 seropositive HCWs and 16 seronegative HCWs were administered MMR vaccines as PEP and following this, no additional cases of mumps were encountered during the maximum incubation period.@*CONCLUSION@#Of the exposed HCWs, 77.1% were mumps-seropositive. Seropositive rates differed according to factors such as age and sex. Eligible HCWs received a MMR vaccine as PEP and no additional mumps cases occurred during the incubation period. It was useful in our infection control activities during the mumps outbreak.

Prevalence and Risk Factors of Carbapenem-resistant Enterobacteriaceae Acquisition in an Emergency Intensive Care Unit in a Tertiary Hospital in Korea: a Case-Control Study

BACKGROUND: Infections caused by carbapenem-resistant Enterobacteriaceae (CRE) are associated with high mortality rates and their treatment is difficult because treatment is limited to certain antibiotics, such as colistin and tigecycline. We aimed to perform active surveillance culture of CRE (ASC-CRE) to monitor the prevalence of CRE acquisition during intensive care unit (ICU) care and to examine the potential risk factors associated with CRE acquisition. METHODS: We conducted ASC-CRE on patients who were admitted to the ICU in the emergency room at a tertiary hospital. Rectal swabs were analyzed using methods established by the Centers for Disease Control and Prevention. To detect carbapenemase-producing CRE, a polymerase chain reaction assay to detect five carbapenemase genes (bla(NDM), bla(KPC), bla(VIM), bla(IMP-1), and bla(OXA-48)) was performed. RESULTS: There were 22 CRE acquisition in 21 patients (2.6%, 21/810) and the incidence of CRE acquisition was 4.3/1,000 person-days, respectively. The most common species detected was Klebsiella pneumoniae (72.7%, 16/22), and 9 carbapenemase-producing CREs (7 bla KPC and 2 bla NDM) were detected. Independent risk factors associated with CRE acquisition were men gender (adjusted odds ratio [aOR], 5.3; 95% confidence interval [CI], 1.3–21.3), history of admission within one year (aOR, 3.9; 95% CI, 1.2–12.1), co-colonization with multidrug-resistant Acinetobacter baumannii (aOR, 15.6; 95% CI, 3.6–67.8) and extended-spectrum β-lactamases-producing bacteria (aOR, 4.7; 95% CI, 1.5–14.6), and exposure to glycopeptide antibiotics (aOR, 3.6; 95% CI, 1.3–9.9). CONCLUSION: The identification of patients with risk factors for CRE acquisition and early detection of CRE acquisition using ASC-CRE may be useful for CRE control.

Erratum: Correction of Author Information and Funding Source: Seroprevalence of Severe Fever with Thrombocytopenia Syndrome in Southeastern Korea, 2015

The authors regret that there were errors in the article. The errors were in one co-author's affiliation and funding source.

Severe Fever with Thrombocytopenia Syndrome Patients with Hemophagocytic Lymphohistiocytosis Retrospectively Identified in Korea, 2008–2013

The incidence of severe fever with thrombocytopenia syndrome (SFTS) has increased in Korea since a first report in 2013. We investigated whether SFTS existed before 2013 using real-time reverse transcription polymerase chain reaction and stored blood samples from febrile patients with thrombocytopenia. Four cases of SFTS were identified, with the earliest occurring in 2008.

A Case of Chronic Gordonia otitidis Lung Infection Initially Regarded as Nontuberculous Mycobacterial Lung Disease / 대한임상미생물학회지

The genus Gordonia is one of the mycolic acid-containing aerobic actinomycetes. This genus has 38 named species that are widespread in the natural environment; however, Gordonia species rarely cause human infections. A 76-year-old woman presented with cough and sputum for over 1 year and was suspected of having nontuberculous mycobacterial (NTM) lung disease. An NTM isolate from the sputum was initially identified as Mycobacterium lentiflavum or Mycobacterium genavense by genotypic identification targeting internal transcribed spacer (ITS). However, the isolate was finally confirmed as Gordonia otitidis by sequencing of 16S rRNA, gyrB and secA1 genes. In patients with suspected NTM lung disease, the etiologic agent might be an organism other than NTM such as G. otitidis but still be identified as NTM without sequencing of 16S rRNA or other genes. Especially in case that a possible NTM isolate is identified as M. lentiflavum or M. genavense by the genotypic method targeting ITS, additional genotypic tests such as sequencing of 16S rRNA and other genes would be necessary for more reliable identification.

Tuberculosis Presenting as a Mediastinal Mass in an Infant / 대한임상미생물학회지

Tuberculosis can occur in various organ systems and may present with diverse manifestations. We report an unusual case of mediastinal tuberculoma in a 3-month-old boy who presented to the hospital after experiencing fever, cough, and progressive pneumonia for two weeks. The chest computed tomography scan indicated a mediastinal mass suggesting lymphoma. However, histological analysis confirmed that the mass was caused by tuberculosis. The present report describes the delayed diagnosis of a disease due to an uncommon presentation. Misdiagnosing unusual cases of tuberculosis results in treatment delays and may lead to an increase in morbidity. Therefore, we suggest that tuberculosis should be included in the differential diagnosis for children presenting with a mediastinal mass, especially in areas with a high prevalence of tuberculosis.

Recovery Rates of Non-Tuberculous Mycobacteria from Clinical Specimens Are Increasing in Korean Tertiary-Care Hospitals

Non-tuberculous mycobacteria (NTM) are being recognized increasingly as the causative agents of opportunistic infections in humans. This study investigated the epidemiologic trends of NTM recovery from various clinical specimens in 2 Korean tertiary-care hospitals. We reviewed the laboratory records of patient samples cultured for mycobacteria between 2009 and 2015 at 2 tertiary-care hospitals in Korea. The medical records for patients with positive NTM samples were also reviewed. During the study period, 144,540 specimens were cultured for mycobacteria. The proportion of NTM-positive samples increased from 23.3% in 2009 to 48.2% in 2015. The 2 most frequently isolated NTM were Mycobacterium intracellulare (38.3%) and M. avium (23.1%). The number of clinically significant diseases caused by NTM in inpatients and outpatients increased from 6.8 to 12.9 per 100,000 patients over the same period. The rates of recovery of NTM from clinical specimens and the number of patients with NTM infections increased significantly (P < 0.001, testing for trend) between 2009 and 2015.

Hidden “Preleukemic Phase” of Chronic Myeloid Leukemia Presenting Without Leukocytosis in the Peripheral Blood Unrelated to Chemotherapy in a Patient Diagnosed With Diffuse Large B Cell Lymphoma

No abstract available.

Seroprevalence of Severe Fever with Thrombocytopenia Syndrome in Southeastern Korea, 2015

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging tick-borne disease characterized by fever, thrombocytopenia and diarrhea. SFTS was firstly reported in Korea in 2013 but its seroprevalence in the country has yet to be investigated. Here, we investigate the seroprevalence of SFTS in a Korean population. A cross-sectional study was conducted on patients who had their sera tested for various reasons at a tertiary university hospital on particular days in May 2015. This study was conducted in a tertiary hospital in southeastern Korea. Total antibodies including immunoglobulin G (IgG) and immunoglobulin M (IgM), specific to SFTS virus (SFTSV) in serum samples were detected by a double-antigen sandwich enzyme-linked immunosorbent assay (ELISA). A total of 1,069 serum samples were tested. Median age was 59 years (range 12–96 years), and 51.5% were male. Overall, 22 patients (2.1%) were tested positive for anti-SFTSV antibodies. The SFTS seroprevalence increased significantly with age (P = 0.034). The seropositive rate of rural area was higher than that of urban area (7.7% vs. 1.9%, P = 0.040). Seropositive rates were not significantly different among underlying diseases. None of the antibody-positive patients showed typical symptoms or laboratory findings of SFTS at the time of sample collection. Results of real-time reverse transcription polymerase chain reaction (RT-PCR) were negative for all the seropositive patients. Our study shows 2.1% SFTS seroprevalence among the patients visiting a tertiary hospital in Korea. Seroprevalence is higher in older and rural population.

In vitro antiviral activity of ribavirin against severe fever with thrombocytopenia syndrome virus

BACKGROUND/AIMS: Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by severe fever with thrombocytopenia syndrome virus (SFTSV), a novel bunyavirus. As yet, there is no effective antiviral therapy for SFTS. Ribavirin is a broad-spectrum antiviral agent, which has been tried for treatment of SFTS. In this study, antiviral activity of ribavirin against SFTSV has been investigated. METHODS: Vero cell-grown SFTSV strain Gangwon/Korea/2012 was treated with ribavirin at various concentrations. Antiviral activity of ribavirin was evaluated by inhibition of the SFTSV cytopathic effect in Vero cells and quantification of viral RNA load in culture supernatant using one-step real-time reverse transcription polymerase chain reaction. Cytotoxicity of ribavirin was determined by a tetrazolium-based colorimetric method. RESULTS: Ribavirin reduced SFTSV titers in a dose-dependent manner, with a half-maximal inhibitory concentration ranged from 3.69 to 8.72 μg/mL. Cytopathic effects were reduced as ribavirin concentration increased. No significant cytotoxicity was detected at ribavirin concentrations of ≤ 31.3 μg/mL. CONCLUSIONS: Ribavirin exhibited inhibitory activity against SFTSV replication in vitro, which suggests that ribavirin can be used as a potential antiviral agent for SFTS.

Cell Population Data NE-SFL and MO-WX From Sysmex XN-3000 Can Provide Additional Information for Exclusion of Acute Promyelocytic Leukemia From Other Acute Myeloid Leukemias: A Preliminary Study

No abstract available.

Correlation of NPM1 Type A Mutation Burden With Clinical Status and Outcomes in Acute Myeloid Leukemia Patients With Mutated NPM1 Type A

BACKGROUND: Nucleophosmin gene (NPM1) mutation may be a good molecular marker for assessing the clinical status and predicting the outcomes in AML patients. We evaluated the applicability of NPM1 type A mutation (NPM1-mutA) quantitation for this purpose. METHODS: Twenty-seven AML patients with normal karyotype but bearing the mutated NPM1 were enrolled in the study, and real-time quantitative PCR of NPM1-mutA was performed on 93 bone marrow (BM) samples (27 samples at diagnosis and 56 at follow-up). The NPM1-mutA allele burdens (represented as the NPM1-mutA/Abelson gene (ABL) ratio) at diagnosis and at follow-up were compared. RESULTS: The median NPM1-mutA/ABL ratio was 1.3287 at diagnosis and 0.092 at 28 days after chemotherapy, corresponding to a median log10 reduction of 1.7061. Significant correlations were observed between BM blast counts and NPM1-mutA quantitation results measured at diagnosis (γ=0.5885, P=0.0012) and after chemotherapy (γ=0.5106, P=0.0065). Total 16 patients achieved morphologic complete remission at 28 days after chemotherapy, and 14 (87.5%) patients showed a >3 log10 reduction of the NPM1-mutA/ABL ratio. The NPM1-mutA allele was detected in each of five patients who had relapsed, giving a median increase of 0.91-fold of the NPM1-mutA/ABL ratio at relapse over that at diagnosis. CONCLUSIONS: The NPM1-mutA quantitation results corresponded to BM assessment results with high stability at relapse, and could predict patient outcomes. Quantitation of the NPM1-mutA burden at follow-up would be useful in the management of AML patients harboring this gene mutation.

Distribution and Antimicrobial Resistance of Streptococcus pneumoniae at Four University Hospitals in Busan and Gyeongnam / 대한임상미생물학회지

BACKGROUND: Streptococcus pneumoniae is the most common human pathogen causing community-acquired pneumonia. There is little information on the recent antimicrobial susceptibility patterns of S. pneumoniae in Busan and Gyeongnam of Korea. The aim of this study was to investigate the distribution and antimicrobial resistance of S. pneumoniae at 4 university hospitals in Busan and Gyeongnam. METHODS: We collected and analyzed the antimicrobial susceptibility results of 850 S. pneumoniae strains isolated from regional 4 university hospitals during the last 2 years from July 2013 through June 2015. RESULTS: Among 850 S. pneumoniae strains, 635 strains were isolated from respiratory specimens, followed by blood (N=121), CSF (N=13), and others (N=81). Antimicrobial susceptibility rates to penicillin, cefotaxime and ceftriaxone were 79.4%, 76.6% and 83.6%, respectively. The resistant rates to erythromycin and clindamycin were 80.9% and 68.2%, respectively. The resistant rates to levofloxacin were 9.2%. There were some differences in resistant rates by age groups, years, and specimen types. CONCLUSION: We found the changes of antimicrobial resistance of S. pneumoniae during the last 2 years. It is necessary to monitor the antimicrobial susceptibility of S. pneumoniae regularly for empirical therapy and for early detection of the changes of resistance.

Prevalence and Clinical Impact of Heterogeneous Vancomycin-Intermediate Staphylococcus aureus Isolated From Hospitalized Patients

BACKGROUND: We estimated the prevalence and clinical impact of heterogeneous vancomycin-intermediate Staphylococcus aureus (hVISA). The concordance between macromethod and glycopeptide resistance detection (GRD) E tests was determined. In addition, predictors of clinical outcomes in hospitalized patients with S. aureus bacteremia (SAB) or pneumonia (SAP) were evaluated. METHODS: We obtained 229 consecutive S. aureus isolates from all hospitalized patients at two university hospitals located in Busan and Yangsan, Korea. Standard, macromethod, and GRD E tests were performed. Additionally, we reviewed the medical records of all patients. Among the 229 patients, predictors of clinical outcomes were analyzed for 107 patients with SAB and 39 with SAP. RESULTS: Among the 229 isolates, 34.5% of S. aureus isolates and 50.7% of methicillin-resistant S. aureus isolates exhibited the hVISA phenotype based on the macromethod E test. hVISA was nearly associated with treatment failure in patients with SAB (P=0.054) and was significantly associated with treatment failure in patients with SAP (P=0.014). However, hVISA was not associated with 30-day mortality in patients with SAB or SAP. The concordance between the macromethod and GRD E tests was 84.2%. CONCLUSIONS: hVISA is quite common in the southeastern part of Korea. hVISA is associated with treatment failure in patients with SAP.

The CD4 slope can be a predictor of immunologic recovery in advanced HIV patients: a case-control study

BACKGROUND/AIMS: Advanced human immunodeficiency virus (HIV) infection, despite sustained viral suppression by highly active antiretroviral therapy (HAART), is a risk factor for poor immunologic recovery. However, some patients with advanced infection do show immunologic recovery. In this study, predictive factors of immunologic recovery were analyzed in advanced HIV patients showing sustained viral suppression. METHODS: A case-control study was conducted in HIV-infected adult patients with HIV-1 RNA or = 500/mm3 at 4 years with HAART). To analyze the CD4 T cell kinetics, the CD4 slope (monthly changes in the CD4 T cell count) was estimated for each patient using a linear regression between the CD4 T cell count and the time since HAART initiation. RESULTS: Of 102 eligible patients, 73 had advanced HIV, and 33 (45.2%) showed immunologic recovery. The median CD4 slopes (cells/mm3 per month) during 0 to 6 and 0 to 12 months of HAART in the 73 advanced patients were significantly higher in responders than in non-responders (0 to 6 months, 38.6 vs. 22.8; 0 to 12 months, 24.5 vs. 13.5). Multivariate analyses showed opportunistic infections at the start of HAART (adjusted odds ratio [OR], 0.28) and a CD4 slope > or = 20 during 0 to 12 months of HAART (adjusted OR, 10.10) were independently associated with immunologic recovery. CONCLUSIONS: The CD4 slope can be an early predictor of long-term immunologic recovery in advanced HIV patients.

Evaluation of Dual-Color Fluorescence In Situ Hybridization With Peptide Nucleic Acid Probes for the Detection of Mycobacterium tuberculosis and Non-Tuberculous Mycobacteria in Clinical Specimens

BACKGROUND: Peptide nucleic acid (PNA) probes are artificial DNA analogues with a hydrophobic nature that can penetrate the mycobacterial cell wall. We evaluated a FISH method for simultaneous detection and identification of Mycobacterium tuberculosis (MTB) and non-tuberculous mycobacteria (NTM) in clinical respiratory specimens using differentially labeled PNA probes. METHODS: PNA probes targeting the mycobacterial 16S ribosomal RNA were synthesized. The cross-reactivity of MTB- and NTM-specific probes was examined with reference strains and 10 other frequently isolated bacterial species. A total of 140 sputum specimens were analyzed, comprising 100 MTB-positive specimens, 21 NTM-positive specimens, and 19 MTB/NTM-negative specimens; all of them were previously confirmed by PCR and culture. The PNA FISH test results were graded by using the United States Centers for Disease Control and Prevention-recommended scale and compared with the results from the fluorochrome acid-fast bacterial stain. RESULTS: The MTB- and NTM-specific PNA probes showed no cross-reactivity with other tested bacterial species. The test results demonstrated 82.9% agreement with the culture results with diagnostic sensitivity of 80.2% and diagnostic specificity of 100.0% (kappa=0.52, 95% confidence interval: 0.370-0.676). CONCLUSIONS: Dual-color PNA FISH showed high specificity for detecting and identifying mycobacteria in clinical specimens. However, because of its relatively low sensitivity, this method could be more applicable to culture confirmation. In application to direct specimens, the possibility of false-negative results needs to be considered.