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Neutralizing antibodies play a critical role in blocking viral infections and in viral clearance during acute infection. The microneutralization assay and enzyme-linked immunosorbent assay (ELISA) targeting the receptor binding domain were performed for 30 patients with mild coronavirus disease (COVID)-19 infections. The elapsed number of days between sample collection and diagnosis was 115 days, and real-time polymerase chain reaction (PCR) cycle threshold (Ct) values at diagnosis were recorded. Clinical characteristics and Ct values were compared between neutralization antibody-positive and -negative patients as measured by the microneutralization assay. Neutralization antibody-positive patients (n = 9) were likely to be older, have low Ct values, have more pneumonia during admission, and have a higher optical density in ELISA than the neutralization antibody-negative patients (n = 21). Elderly people seemed to have a higher viral load causing more pneumonia and to produce more neutralization antibodies. Neutralization antibodies persisted in only 30% of patients as detected by microneutralization test after 100 days of diagnosis.
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Background@#Group A streptococcus (GAS) is the most common cause of bacterial pharyngitis. This study aimed to characterize the molecular epidemiology of GAS infection using an emm-typing and emm-clustering approach. @*Methods@#A total of 372 patients from Changwon who showed pharyngitis symptoms were recruited during the sampling period of 2018–2019 and throat cultures were obtained from them. emm typing was performed using polymerase chain reaction (PCR) and direct sequencing. emm genotypes and GAS clusters were classified based on a web-based database. @*Results@#Of the 372 throat swab specimens, 101 (27.2%) were positive for GAS. emm typing analysis was performed on 59 GAS isolates. The most prevalent emm type was emm89 (20.3%), followed by emm12 (16.9%). Seven emm clusters were identified: E4 (emm89/ emm28, 32.2%), A-C4 (emm12, 16.9%), E1 (emm4, 13.6%), A-C5 (emm3, 10.2%), E6 (emm75, 8.5%), M6 (emm6, 8.5%), and A-C3 (emm1, 6.8%). @*Conclusion@#Diverse and temporal changes were observed in the distribution of emm types and clusters of GAS. Continuous surveillance based on emm genotyping is needed to monitor the epidemiological characteristics of GAS pharyngitis.
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Background@#Blood culture is essential for diagnosis of sepsis. However, usually the available blood volume is not sufficient to meet the guidelines. Thus, periodic monitoring and feedback are essential to improve the quality of blood cultures. @*Methods@#We analyzed blood cultures requested between November 2018 and June 2019, and provided educational intervention and coaching for phlebotomists at the end of February 2019. Then, we evaluated the impact of education on blood cultures in a secondary‑care hospital. Blood volume, positive rate, contamination rate, and time to detection (TTD) were compared between the pre- (November 2018 to February, 2019) and post-intervention periods (March to June, 2019). @*Results@#The average blood volume increased significantly from 5.4 mL to 7.1 mL (P < 0.0001) (35.2%) after intervention. Accordingly, the proportion of optimal blood volume (8–12 mL) increased from 9.1% to 37.8% (P < 0.0001). Before the intervention, the positivity rate was 9.6% and the contamination rate was 0.5%, whereas after the intervention, the positivity rate decreased to 9.1% and the contamination rate increased to 1.1%. TTD improved from 14.7 hours to 13.1 hours (P = 0.0420). @*Conclusion@#The educational intervention of the phlebotomy team improved the quality of blood cultures, especially blood volumes and TTD. However, the positivity rate did not increase, suggesting that it is affected not only by the blood volumes but also by the severity of the underlying illnesses of the patient in a secondary-care hospital.
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Background@#The clindamycin-resistant erythromycin-susceptible (CRES) phenotype is rare in Streptococcus agalactiae (group B streptococci). We aimed to determine the molecular characteristics of CRES S. agalactiae using whole genome sequencing (WGS). @*Methods@#Sixty-six S. agalactiae isolates obtained from blood (N=26), cerebrospinal fluid (N=10), urine (N=17), and vaginal discharge (N=13) between 2010 and 2017 in Korea were subjected to WGS. Based on the WGS data, we analyzed antimicrobial resistance (AMR) determinants, sequence types (STs), capsular polysaccharide (CPS) genotypes, and virulence gene profiles, and constructed a phylogenetic tree. We included the clindamycin-susceptible erythromycin-resistant (CSER) phenotype for comparison. @*Results@#We identified seven CRES S. agalactiae isolates from urine (N=5) and vaginal discharge (N=2) collected between 2010 and 2011. All CRES isolates harbored AMR determinants of lnu(B), lsa(E), and aac(6’)-aph(2’’), revealed ST19 and CPS genotype III, and had a virulence gene profile of rib-lmb-cylE. Phylogenetic tree analysis revealed that all CRES isolates belonged to the same cluster, suggesting a clonal distribution. In contrast, seven CSER isolates showed a diverse distribution and clustered separately from the CRES isolates. @*Conclusions@#CRES isolates collected between 2010 and 2011 showed a unique cluster with ST19 and CPS genotype III in Korea. This is the first report on WGS-based characteristics of S. agalactiae in Korea.
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Background@#Pharyngitis is one of the most common conditions encountered in primary health care facilities. Accurate differentiation of group A streptococcus (GAS) infection from viral infection is difficult. The STANDARD F Strep A Ag FIA (SD BIOSENSOR, Korea) is a rapid antigen detection test (RADT) that has been recently developed for diagnosing GAS pharyngitis. In this study, we evaluated the diagnostic performance of the STANDARD F Strep A Ag FIA and compared the results between the RADT and conventional throat culture. @*Methods@#Throat swab samples were obtained from a total of 372 children presenting pharyngitis symptoms in five pediatric clinics in Changwon, Korea from July 2018 to October 2019. A comparative study between STANDARD F Strep A Ag FIA and Sofia Strep A FIA (Quidel, USA) was performed. Two throat swabs were taken simultaneously from each patient for RADT. The third throat swab was stored in a transport tube containing Stuart's transport medium for culture. Performance and kappa index of STANDARD F Strep A Ag FIA were evaluated. @*Results@#GAS infection was detected in 29.3% (109/372) patients, using the STANDARD F Strep A Ag FIA. The sensitivity, specificity, positive predictive value, and negative predictive value were 95.0%, 95.2%, 88.1%, and 98.1%, respectively. The STANDARD F Strep A Ag FIA showed an excellent concordance rate of 96.5% and a kappa value of 0.89 compared to Sofia Strep A FIA. @*Conclusion@#The STANDARD F Strep A Ag FIA demonstrated an excellent performance along with Sofia Strep A FIA for the diagnosis of GAS pharyngitis.
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Long QT syndrome (LQTS) is an inherited cardiac disease characterized by a prolonged heart rate-corrected QT (QTc) interval. We investigated the genetic causes in patients with prolonged QTc intervals who were negative for pathogenic variants in three major LQTS-related genes (KCNQ1, KCNH2, and SCN5A). Molecular genetic testing was performed using a panel including 13 LQTS-related genes and 67 additional genes implicated in other cardiac diseases. Overall, putative genetic causes of prolonged QTc interval were identified in three of the 30 patients (10%). Among the LQTS-related genes, we detected a previously reported pathogenic variant, CACNA1C c.1552C>T, responsible for cardiac-only Timothy syndrome. Among the genes related to other cardiac diseases, a likely pathogenic variant, RYR2 c.11995A>G, was identified in a patient with catecholaminergic polymorphic ventricular tachycardia. Another patient who developed dilated cardiomyopathy with prolonged QTc interval was found to carry a likely pathogenic variant, TAZ c.718G>A, associated with infantile dilated cardiomyopathy. Comprehensive screening of genetic variants using multigene panel sequencing enables detection of genetic variants with a possible involvement in QTc interval prolongation, thus uncovering unknown molecular mechanisms underlying LQTS.
Subject(s)
Humans , Cardiomyopathy, Dilated , Heart , Heart Diseases , Long QT Syndrome , Mass Screening , Molecular Biology , Ryanodine Receptor Calcium Release Channel , Tachycardia, VentricularABSTRACT
BACKGROUND: The major genetic cause of Currarino syndrome (CS), a congenital malformation syndrome typically characterized by sacral agenesis, anorectal malformation, and presence of a pre-sacral mass, is known to be pathogenic variants in motor neuron and pancreas homeobox 1 (MNX1), which exist in almost all familial cases and 30% of sporadic cases. Less commonly, a large deletion or a complex rearrangement involving the 7q36 region is associated with CS. We investigated the spectrum of MNX1 pathogenic variants and associated clinical features in the Korean patients with CS. METHODS: We enrolled 25 patients with CS, including 24 sporadic cases and one familial case. Direct sequencing of MNX1 and multiplex ligation-dependent probe amplification were performed. We also analyzed clinical phenotypes and evaluated genotype-phenotype correlations. RESULTS: We identified six novel variants amongst a total of six null variants, one missense variant, and one large deletion. The null variants included four frameshift variants (p.Gly98Alafs*124, p.Gly145Alafs*77, p.Gly151Leufs*67, and p.Ala216Profs*5) and two nonsense variants (p.Tyr186* and p.Gln212*). The missense variant, p.Lys295Gln, was located in the highly-conserved homeobox domain and was predicted to be deleterious. A large deletion involving the 7q36 region was detected in one patient. Pathogenic variants in MNX1 were detected in 28% of all CS cases and 25% of sporadic cases. The clinical phenotype was variable in patients with and without pathogenic variants; no significant genotype-phenotype correlation was observed. CONCLUSIONS: This study revealed the spectrum and phenotypic variability of MNX1 pathogenic variants in the Korean population.
Subject(s)
Humans , Genes, Homeobox , Genetic Association Studies , Motor Neurons , Multiplex Polymerase Chain Reaction , Pancreas , PhenotypeABSTRACT
Psychrobacter sanguinis has been described as a Gram-negative, aerobic coccobacilli originally isolated from environments and seaweed samples. To date, 6 cases of P. sanguinis infection have been reported. A 53-year-old male was admitted with a generalized tonic seizure lasting for 1 minute with loss of consciousness and a mild fever of 37.8℃. A Gram stain revealed Gram-negative, small, and coccobacilli-shaped bacteria on blood culture. Automated microbiology analyzer identification using the BD BACTEC FX (BD Diagnostics, Germany) and VITEK2 (bioMérieux, France) systems indicated the presence of Methylobacterium spp., Aeromonas salmonicida, and the Moraxella group with low discrimination. The GenBank Basic Local Alignment Search Tool and an Ez-Taxon database search revealed that the 16S rRNA gene sequence of the isolate showed 99.30% and 99.88% homology to 859 base-pairs of the corresponding sequences of P. sanguinis, respectively (GenBank accession numbers JX501674.1 and HM212667.1). To the best of our knowledge, this is the first human case of P. sanguinis bacteremia in Korea. It is notable that we identified a case based on blood specimens that previously had been misidentified by a commercially automated identification analyzer. We utilized 16S rRNA gene sequencing as a secondary method for correctly identifying this microorganism.
Subject(s)
Humans , Male , Middle Aged , Aeromonas salmonicida , Bacteremia , Bacteria , Databases, Nucleic Acid , Discrimination, Psychological , Fever , Genes, rRNA , Korea , Methods , Methylobacterium , Moraxella , Psychrobacter , RNA, Ribosomal, 16S , Seaweed , Seizures , UnconsciousnessABSTRACT
This study was conducted to evaluate the usefulness of coronary arterial profiles from normal dogs (11 animals) and canines (six dogs) with experimental myocardial infarction (MI) induced by ligation of the left coronary artery (LCA). Blood velocity of the LCA and right coronary artery (RCA) were evaluated following transthoracic pulsed-wave Doppler echocardiography. The LCA was observed as an infundibular shape, located adjacent to the sinus of Valsalva. The RCA appeared as a tubular structure located 12 o'clock relative to the aorta. In normal dogs, the LCA and RCA mean peak diastolic velocities were 20.84 +/- 3.24 and 19.47 +/- 2.67 cm/sec, respectively. The LCA and RCA mean diastolic deceleration times were 0.91 +/- 0.14 sec and 1.13 +/- 0.20 sec, respectively. In dogs with MI, the LCA had significantly (p < 0.01) lower peak velocities (14.82 +/- 1.61 cm/sec) than the RCA (31.61 +/- 2.34 cm/sec). The RCA had a significantly (p < 0.01) rapid diastolic deceleration time (0.71 +/- 0.06 sec) than that found in the LCA (1.02 +/- 0.22 sec) of MI dogs. In conclusion, these profiles may serve as a differential factor for evaluating cardiomyopathy in dogs.