Performance evaluation of STANDARD Q COVID-19 Ag home test for the diagnosis of COVID-19 during early symptom onset.

BACKGROUND: Surveillance and control of SARS-CoV-2 outbreak through gold standard detection, that is, real-time polymerase chain reaction (RT-PCR), become a great obstacle, especially in overwhelming outbreaks. In this study, we aimed to analyze the performance of rapid antigen home test (RAHT) as an alternative detection method compared with RT-PCR. METHODS: In total, 79 COVID-19-positive and 217 COVID-19-negative patients confirmed by RT-PCR were enrolled in this study. A duration from symptom onset to COVID-19 confirmation of <5 days was considered a recruiting criterion for COVID-19-positive cases. A nasal cavity specimen was collected for the RAHT, and a nasopharyngeal swab specimen was collected for RT-PCR. RESULTS: Sensitivity of the STANDARD Q COVID-19 Ag Home Test (SD Biosensor, Korea), compared with RT-PCR, was 94.94% (75/79) (95% [confidence interval] CI, 87.54%-98.60%), and specificity was 100%. Sensitivity was significantly higher in symptomatic patients (98.00%) than in asymptomatic (89.66%) patients (p-value = 0.03). There was no difference in sensitivity according to the duration of symptom onset to confirmation (100% for 0-2 days and 96.97% for 3-5 days, respectively) (p-value = 1.00). The RAHT detected all 51 COVID-19 patients whose Ct values were ≤25 (100%), whereas sensitivity was 73.33% (11/15) among patients with Ct values >25 (p-value = 0.01). CONCLUSION: The RAHT showed an excellent sensitivity for COVID-19-confirmed cases, especially for those with symptoms. There was a decrease in sensitivity when the Ct value is over 25, indicating that RAHT screening may be useful during the early phase of symptom onset, when the viral numbers are higher and it is more transmissible.

Unveiling Genetic Variants Underlying Vitamin D Deficiency in Multiple Korean Cohorts by a Genome-Wide Association Study.

BACKGROUND: Epidemiological data have shown that vitamin D deficiency is highly prevalent in Korea. Genetic factors influencing vitamin D deficiency in humans have been studied in Europe but are less known in East Asian countries, including Korea. We aimed to investigate the genetic factors related to vitamin D levels in Korean people using a genome-wide association study (GWAS). METHODS: We included 12,642 subjects from three different genetic cohorts consisting of Korean participants. The GWAS was performed on 7,590 individuals using linear or logistic regression meta- and mega-analyses. After identifying significant single nucleotide polymorphisms (SNPs), we calculated heritability and performed replication and rare variant analyses. In addition, expression quantitative trait locus (eQTL) analysis for significant SNPs was performed. RESULTS: rs12803256, in the actin epsilon 1, pseudogene (ACTE1P) gene, was identified as a novel polymorphism associated with vitamin D deficiency. SNPs, such as rs11723621 and rs7041, in the group-specific component gene (GC) and rs11023332 in the phosphodiesterase 3B (PDE3B) gene were significantly associated with vitamin D deficiency in both meta- and mega-analyses. The SNP heritability of the vitamin D concentration was estimated to be 7.23%. eQTL analysis for rs12803256 for the genes related to vitamin D metabolism, including glutamine-dependent NAD(+) synthetase (NADSYN1) and 7-dehydrocholesterol reductase (DHCR7), showed significantly different expression according to alleles. CONCLUSION: The genetic factors underlying vitamin D deficiency in Korea included polymorphisms in the GC, PDE3B, NADSYN1, and ACTE1P genes. The biological mechanism of a non-coding SNP (rs12803256) for DHCR7/NADSYN1 on vitamin D concentrations is unclear, warranting further investigations.

Status of Four Trace Elements in Elderly Patients with Online Hemodiafiltration.

BACKGROUND: Essential trace elements play key roles in multiple biological systems, and hemodialysis patients are at risk for deficiency of essential trace elements. The aim of the study was to assess the essential element status in end stage renal disease patients undergoing online hemodiafiltration (online HDF) in outpatient dialysis clinic. METHODS: A total of 28 Korean patients with regular online HDF were included. Blood samples were collected before and after one HDF session, and serum concentrations of zinc, copper, selenium, and manganese were simulta-neously measured by inductively coupled plasma mass spectrometry. RESULTS: Selenium, zinc, copper deficiencies were observed in 71.4%, 35.8%, and 21.4%, compared with the reference range. No patients revealed manganese deficiency. After the HDF, the post-HDF level significantly increased in all trace elements, compared with the pre-HDF (11.2% for selenium, 10.7% for copper, and 6.6% for zinc). However, 50% patients were still deficient for selenium at the post-HDF. CONCLUSIONS: Our data suggest that the patients undergoing online HDF are at an increased risk of trace element deficiency, especially for selenium.

A Case of Chronic Neutrophilic Leukemia Incidentally Detected by 18F-FDG PET/CT.

Chronic neutrophilic leukemia (CNL) is a rare, potentially aggressive, myeloproliferative neoplasm. To the best of our knowledge, there are no previous reports dealing with 18F-FDG PET findings in CNL. We describe a case of CNL in a 69-year-old male, imaged with 18F-FDG PET/CT at diagnosis and during treatment.

Impact of Community-Onset Methicillin-Resistant Staphylococcus aureus on Staphylococcus aureus Bacteremia in a Central Korea Veterans Health Service Hospital.

BACKGROUND: No study has examined the epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) bacteremia in Korean veterans' hospitals. We investigated the microbiological and clinical epidemiology of S. aureus bacteremia at the central Veterans Health Services (VHS) hospital in Korea. METHODS: Patients with S. aureus bacteremia were consecutively enrolled from February to August 2015. Bacteremia was classified as hospital-acquired (HA), community-onset healthcare-associated (COHA), or community-acquired (CA). MRSA bacteremia risk factors were analyzed. Species identification, antimicrobial susceptibility, and presence of luk and tst were tested. Staphylococcal cassette chromosome mec (SCCmec) typing, spa sequence typing agr polymorphism typing, and multilocus sequence typing were performed. Biofilm production and δ-hemolysin activity were measured to determine agr function. RESULTS: In total, 60 patients were enrolled (30 HA, 23 COHA, and seven CA bacteremia); 44 (73.3%) had MRSA bacteremia (26 HA, 16 COHA, and two CA). MRSA bacteremia occurred more frequently in non-CA patients and those who had received antibiotic treatment within the past month (P<0.05). The major MRSA strains comprised 24 ST5-agr2-SCCmecII, 11 ST72-agr 1-SCCmecIV, and five ST8-agr1-SCCmecIV strains. Of 26 agr2-SCCmecII strains, including two MSSA strains, 25 were multidrug-resistant, 18 were tst-positive, and 13 were agr-defective, whereas only five of the 18 agr1-SCCmecIV strains were multidrug-resistant, and all were tst-negative and agr-intact. agr1-SCCmecIV and ST8-agr1-SCCmecIV strains were more likely than agr2-SCCmecII strains to be COHA. CONCLUSIONS: MRSA was highly prevalent in both COHA and HA bacteremia. The introduction of virulent CA-MRSA strains may be an important cause of increased HA-MRSA bacteremia in VHS hospitals.

Performance evaluation of cobas HBV real-time PCR assay on Roche cobas 4800 System in comparison with COBAS AmpliPrep/COBAS TaqMan HBV Test.

BACKGROUND: Hepatitis B virus (HBV) nucleic acid amplification testing (NAAT) is important for the diagnosis and management of HBV infection. We evaluated the analytical performance of the cobas HBV NAAT (Roche Diagnostics GmbH, Mannheim, Germany) on the cobas 4800 System in comparison with COBAS AmpliPrep/COBAS TaqMan HBV Test (CAP/CTM HBV). METHODS: Precision was evaluated using three levels of cobas HBV/HCV/HIV-1 Control Kit, and linearity was evaluated across the anticipated measuring range (10.0-1.0×109 IU/mL) at seven levels using clinical samples. Detection capability, including limit of blank (LOB), limit of detection (LOD) and limit of quantitation (LOQ), was verified using the 4th WHO International Standard for HBV DNA for NAT (NIBSC code: 10/266). Correlation between the two systems was compared using 205 clinical samples (102 sera and 103 EDTA plasma). RESULTS: Repeatability and total imprecision (coefficient of variation) ranged from 0.5% to 3.8% and from 0.5% to 3.5%, respectively. Linearity (coefficient of determination, R2) was 0.999. LOB, LOD and LOQ were all acceptable within the observed proportion rate (85%). Correlation was very high between the two systems in both serum and plasma samples (correlation coefficient [r]=0.995). CONCLUSIONS: The new cobas HBV real-time PCR assay on the cobas 4800 System showed reliable analytical performances.

Reduced NK cell IFN-γ secretion and psychological stress are independently associated with herpes zoster.

The pathogenesis of herpes zoster is closely linked to reduced varicella-zoster virus-specific cell-mediated immunity. However, little is known about the interplay between natural killer cells and psychological stress in the pathogenesis of herpes zoster. This study aimed to investigate possible associations among natural killer cells, T cells and psychological stress in herpes zoster. Interferon-gamma secretion from natural killer cell, psychological stress events, stress cognition scale scores and cytomegalovirus-specific cell-mediated immunity were compared between 44 patients with herpes zoster and 44 age- and gender-matched control subjects. A significantly lower median level of interferon-gamma secreted by natural killer cells was observed in patients with a recent diagnosis of herpes zoster than in control subjects (582.7 pg/ml vs. 1783 pg/ml; P = 0.004), whereas cytomegalovirus-specific cell-mediated immunity was not associated with herpes zoster. Psychological stress events and high stress cognition scale scores were significantly associated in patients with herpes zoster (P<0.001 and P = 0.037, respectively). However, reduced interferon-gamma secretion from natural killer cell and psychological stress were not associated. In conclusion, patients with a recent diagnosis of herpes zoster display reduced interferon-gamma secretion from natural killer cells and frequent previous psychological stress events compared with controls. However, reduced natural killer cell activity is not an immunological mediator between psychological stress and herpes zoster.

A Case of Peritoneal Dialysis-related Peritonitis Caused by Aeromonas Hydrophila in the Patient Receiving Automated Peritoneal Dialysis.

Peritoneal dialysis (PD)-related peritonitis is a major cause of injury and technique failure in patients undergoing PD. Aeromonas hydrophila is ubiquitous in the environment, and is a Gram-negative rod associated with infections in fish and amphibians in most cases; however, it can also cause opportunistic infections in immunocompromised patients. We report a case of A. hydrophila peritonitis in a 56-year-old male on automated PD. Peritonitis may have been caused by contamination of the Set Plus, a component of the automated peritoneal dialysis device. Although Set Plus is disposable, the patient reused the product by cleansing with tap water. He was successfully treated with intraperitoneally-administered ceftazidime and has been well without recurrence for more than 2 years.

Prevalence and clinical significance of occult hepatitis B virus infection among renal transplant recipients in Korea.

BACKGROUND: Occult hepatitis B infection (OBI) is the presence of hepatitis B virus (HBV) DNA in serum or hepatic tissue without detectable hepatitis B surface antigen (HBsAg) in serum. Kidney disease patients in the post-renal transplantation period are in a specific situation as a result of the high pre-transplantational risk of HBV infection and post-transplantational immunosuppression. We studied the pre-transplantational prevalence and post-transplantational influence of OBI on kidney transplantation patients. METHODS: We investigated pre-transplantational serum samples of 217 HBsAg-negative patients of post-renal transplant status for the presence of HBV DNA by real-time quantitative polymerase chain reaction. Serologic markers for HBV and hepatitis C virus (HCV) infection as well as liver enzymes were analyzed. RESULTS: We detected HBV DNA in 2.3% (5/217) of HBsAg-negative patients, and the median HBV DNA titer was 33.15 copies/ml (range 30.6-144.6 copies/ml). Among the 5 OBI patients, 2 had hepatitis B surface antibodies (anti-HBs) and 1 had hepatitis B core antibodies (anti-HBc IgG). None of the patients with OBI were co-infected with HCV. There was no evidence of reactivation of OBI during the 36-month (range 27-63 months) follow-up monitoring period after transplantation, in spite of immune suppression to prevent rejection. CONCLUSIONS: The prevalence of occult HBV in the setting of renal transplantation was higher than that in the general population of Korea, and no reactivation of hepatitis B was observed in patients with OBI in the post-renal transplantation period.

Placental alkaline phosphatase isoenzyme in quality control materials may be a source of variability in alkaline phosphatase activity.

OBJECTIVES: To determine the cause of discrepancies in the alkaline phosphatase (ALP) activities of quality control (QC) materials in two different analyzers using IFCC method. DESIGN AND METHODS: ALP activities of patients' samples and QC materials (QC1 and QC2 from Bio-Rad) measured using TBA-200FR and Synchron LX-20 analyzers were compared and isoenzyme electrophoresis was done. Fractional mixing of bone or liver ALP with placental ALP was performed. ALP activities of QC materials were measured in TBA-200FR with pH-modified reagents. RESULTS: ALP activities of QC materials were significantly lower in TBA-200FR than in LX-20. Placental ALP comprised 57% of QC1 and 95% of QC2. Higher placental ALP proportion in the mixture with bone or liver ALP resulted in lower ALP activities in TBA-200FR. The discrepancy in ALPs of QC materials decreased when measured with pH-modified reagents. CONCLUSION: Placental ALP in QC materials and differences in reagents' pH caused the discrepancy in ALP activities.

A case of histiocytic sarcoma presenting with primary bone marrow involvement.

Histiocytic sarcoma (HS) is a very rare neoplasm that often shows an aggressive clinical course and systemic symptoms, such as fever, weight loss, adenopathy, hepatosplenomegaly and pancytopenia. It may present as localized or disseminated disease. We describe here a 63-yr-old male who manifested systemic symptoms, including fever, weight loss and generalized weakness. Abdominal and chest computed tomography failed to show specific findings, but there was suspicion of multiple bony changes at the lumbar spine. Fusion whole body positron emission tomography, bone scan and lumbar spine magnetic resonance imaging showed multiple bone lesions, suggesting a malignancy involving the bone marrow (BM). Several BM and bone biopsies were inconclusive for diagnosis. Necropsy showed replacement of the BM by a diffuse proliferation of neoplastic cells with markedly increased cellularity (95%). The neoplastic cells were positive for lysozyme and CD68, but negative for T- and B-cell lineage markers, and megakaryocytic, epithelial, muscular and melanocytic markers. Morphologic findings also distinguished it from other dendritic cell neoplasms.

[Evaluation of combination of BACTEC mycobacteria growth indicator tube 960 system and Ogawa media for mycobacterial culture].

BACKGROUND: The combined use of liquid media and solid media is recommended for mycobacterial culture. We evaluated diagnostic performance of combination of BACTEC Mycobacteria Growth Indicator Tube (MGIT; Becton Dickinson, USA) and 2% Ogawa media (Korean Institute of Tuberculosis, Korea) for recovery of mycobacteria. METHODS: In September 2007, 1,764 specimens from 1,059 patients were cultured with MGIT and Ogawa. Acid fast bacilli (AFB) smear was fluorochrome-stained. The isolates were identified into Mycobacterium tuberculosis (MTB) and nontuberculous mycobacteria (NTM) with PCR using Seeplex TB Detection Kit (Seegene, Korea). Recovery rate, time to detection (TTD), contamination rate, mixed growth rate and species distribution were analyzed. RESULTS: Two hundred thirty-five specimens (13.3%) from 165 patients (15.6%) were positive for mycobacterial culture. Recovery rates of mycobacteria from the group using both media, MGIT only, and Ogawa only were 13.3%, 12.1%, and 7.8%, respectively. While MGIT recovered 98.9% of MTB and 79.7% of NTM, Ogawa recovered 65.9% of MTB and 54.1% of NTM. TTDs of total mycobacteria/MTB/NTM in MGIT and Ogawa were 10.6/11.4/9.7 days and 31/29/33 days, respectively. MGIT TTDs of total mycobacteria/MTB/NTM from AFB-positive specimens were significantly shorter than those of AFB-negative specimens; 8.2/9.5/4.4 days vs 11.6/12.7/10.7 days. Contamination and mixed growth rate of MGIT were 9.6% and 3.7%. Primary culture of Ogawa recovered 1 MTB and 1 NTM among the 170 MGIT-contaminated specimens and 38 mycobacteria among 66 specimens that showed mixed cultures of MGIT. CONCLUSIONS: MGIT warrants sensitive and rapid isolation of mycobacteria. However, the combination of MGIT and Ogawa is more desirable to recover mycobacteria in the case of contaminations or mixed cultures.