Case of Chryseobacterium hominis Isolated from Human Blood Drawn Through Peripherally Inserted Central Catheter

Chryseobacterium hominis is non-fermenting Gram-negative rod that was first identified as a novel species in 2007. Here, we report the first clinical case of C. hominis bacteremia, which was confirmed by MALDI-TOF MS and 16S rRNA gene sequencing. A 16-year-old boy diagnosed with acute lymphoblastic leukemia was hospitalized for three months. Two sets of blood culture test through a peripherally inserted central catheter (PICC), which was inserted a month ago, was performed when his white blood cell count declined and he had a high fever. Colonies of medium sizes that looked round, mucoid, sticky, and grayish on blood and chocolate agar plates were observed. Identification of bacteria using the VITEK MALDI-TOF MS system (BioMérieux, France) was not successful and the VITEK 2 system (BioMérieux, USA) indicated Sphingomonas paucimobilis, with a questionable level of confidence (92%). However, Microflex LT Biotyper (Bruker Daltonics, Germany) showed C. homins (log score: 1.81) and sequence of 16S rRNA showed a 100% identity with C. hominis. Piperacillin-tazobactam was administered since the isolate was susceptible to piperacillin-tazobactam but C. hominis showed growth in the next four follow-up culture of blood drawn through PICC. The fever subsided only after PICC was changed. The clinical prognosis and antimicrobial susceptibility test of C. hominis should be further studied.ope

Clinical Application of Circulating Tumor DNA Analysis

Liquid biopsy using circulating tumor DNA helps overcome the limitations of conventional tissue testing. Non-invasive molecular profiling using circulating tumor DNA is increasingly being used to diagnose cancer, stratify risk, and select targeted treatments. By understanding the biological characteristics of circulating tumor DNA and patient factors that can affect concentrations of circulating tumor DNA as well as optimizing the techniques, the clinical utilization of circulating tumor DNA tests can be improved. It is also necessary to formulate guidelines for the administration and reporting of circulating tumor DNA tests.ope

Low-Dose Triple Antihypertensive Combination Therapy in Patients with Hypertension: A Randomized, Double-Blind, Phase II Study

Purpose: We evaluated the dose-responsiveness, efficacy, and safety of low-dose triple antihypertensive combination therapies in patients with mild-to-moderate hypertension. Patients and methods: After a 1 to 2-week placebo run-in period, 248 patients were randomized to the half-dose triple combination (amlodipine 2.5 mg + losartan 25 mg + chlorthalidone 6.25 mg), third-dose triple combination (amlodipine 1.67 mg + losartan 16.67 mg + chlorthalidone 4.17 mg), quarter-dose triple combination (amlodipine 1.25 mg + losartan 12.5 mg + chlorthalidone 3.13mg), amlodipine 10mg, amlodipine 5mg, losartan 100mg, and placebo groups for 8 weeks. The primary outcome was the mean change in systolic blood pressure (SBP) from baseline to week 8. Results: The placebo-corrected SBP reductions of the half-dose, third-dose, quarter-dose combination, amlodipine 10 mg, amlodipine 5 mg and losartan 100 mg treatments were -17.2, -19.5, -14.9, -18.5, -11.3 and -9.9 mmHg, respectively. The BP control and response rates were significantly higher in the half-dose, third-dose, and quarter-dose combination groups than in the placebo group (all p < 0.01). Despite no intergroup differences in study drug-related adverse events, ankle circumference increased significantly in the amlodipine group compared to those in the combination treatment groups. The quarter-dose combination, amlodipine 5 mg, and losartan 100 mg groups showed similar SBP reduction and BP response rates. The SBP reduction and BP response rate in the third-dose and half-dose combination groups were not significantly different from those in the amlodipine 10 mg group but superior to those in the losartan 100 mg group. Conclusion: Low-dose triple combination therapies could be effective as antihypertensive therapies. Trial registration: ClinicalTrials.gov identifier NCT03897868.ope

Comparison of High-Throughput Fully Automated Immunoanalyzers for Detecting Hepatitis B Virus Infection

Context.—: High-throughput automated immunoanalyzers for hepatitis B virus serologic markers have been introduced but have not been compared to existing systems. Objective.—: To compare hepatitis B surface antigen, hepatitis B surface antibody, and total hepatitis B core antibody analyses between our Architect i2000 platform and newer high-throughput fully automated immunoanalyzers. Design.—: From May to June 2018, a total of 932, 914, and 1055 samples tested for hepatitis B surface antigen, hepatitis B surface antibody, and total hepatitis B core antibody, respectively, with the Architect i2000 system for routine testing in our center were tested again with Alinity i, Atellica IM, and Cobas e801 systems. Results.—: Total concordance rates among the systems were 98.0%, 89.5%, and 93.0% for hepatitis B surface antigen, hepatitis B surface antibody, and total hepatitis B core antibody, respectively. Cohen's κ values exceeded 0.8. The correlations between serum hepatitis B surface antibody levels quantified by all 4 systems were high (r > 0.85). The hepatitis B surface antibody averages were greater for the Alinity i, Atellica IM, and Cobas e801 than for the Architect i2000 (P < .001). Conclusions.—: Alinity i, Atellica IM, and Cobas e801 automated immunoanalyzers performed well when compared with the existing Architect i2000 system with regard to detection of hepatitis B viral infection. However, the new systems have higher titer and positivity rates for hepatitis B surface antibody and are more sensitive. Notably, the Atellica IM has a lower positive rate for total hepatitis B core antibody than does the Architect i2000.ope

Beneficial Chromosomal Integration of the Genes for CTX-M Extended-Spectrum β-Lactamase in Klebsiella pneumoniae for Stable Propagation

The acquired CTX-M-type extended-spectrum-β-lactamase (ESBL)-producing Enterobacterales are of great concern in clinical settings because they limit therapeutic options for patients infected by the pathogens. An intriguing clonality of CTX-M ESBL-producing Klebsiella pneumoniae blood isolates was observed from a national cohort study, and comparative genomics were assessed for the 115 K. pneumoniae blood isolates carrying the bla CTX-M gene. The plasmid preference of particular clones of a sequence type (ST) was assessed by liquid mating. A quarter of the bla CTX-M gene-carrying K. pneumoniae blood isolates harbor the gene in their chromosome, and most of those with the built-in bla CTX-M gene belonged either to ST307 or ST48. Notably, all 16 K. pneumoniae ST48 isolates harbored two copies of the bla CTX-M-15 gene in the chromosome. The chromosomal integration of the bla CTX-M-15 gene was mostly derived from the ISEcp1-targeting 5-bp AT-rich locus in the chromosome. The IS26-mediated chromosomal integration occurred when the upstream ISEcp1 from the bla CTX-M gene was truncated, targeting the anchor IS26 copy in the chromosome. Higher transfer efficiency of the bla CTX-M-15 gene-carrying FIA:R plasmid was observed in ST17 than that of the bla CTX-M-14 gene-carrying FIB:FII plasmid. The transfer efficiency of the plasmid differed by isolate among the ST307 members. The K. pneumoniae clones ST307 and ST48 harboring the bla CTX-M-15 gene in the chromosome were able to disseminate stably in clinical settings regardless of the environmental pressure, and the current population of K. pneumoniae blood isolates was constructed. Further follow-up is needed for the epidemiology of this antimicrobial resistance.IMPORTANCE Dominant F-type plasmids harboring the gene have been pointed out to be responsible for the dissemination of the CTX-M extended-spectrum-β-lactamase (ESBL)-producing K. pneumoniae Recently, the emergence of K. pneumoniae isolates with the bla CTX-M gene in their chromosomes has been reported occasionally worldwide. Such a chromosomal location of the resistance gene could be beneficial for stable propagation, as was the Acinetobacter baumannii ST191 harboring chromosomal bla OXA-23 that is endemic to South Korea. Through the present study, particular clones were identified as having built-in resistance genes in their chromosomes, and the chromosomal integration events were tracked by assessing their genomes. The cefotaxime-resistant K. pneumoniae clones of this study were particularized as results of the fastidiousness for plasmids to acquire the bla CTX-M gene for securing the diversity and of the chromosomal addiction of the bla CTX-M gene for ensuring propagation.ope

Adult-onset MELAS syndrome in a 51-year-old woman without typical clinical manifestations: a case report

Background: Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome is a multi-organ disorder resulting from mitochondrial DNA (mtDNA) mutations. We report a case of suspected MELAS syndrome that progressed to left ventricular dysfunction 24 years after an initial diagnosis of atrioventricular block (AVB). Case summary: A 51-year-old woman was referred to heart failure clinic because of dyspnoea on exertion and progressive cardiomegaly. She had a dual-chamber pacemaker implanted for 24 years because of a high-degree AVB. She was treated for diabetes mellitus for 23 years and used hearing aids for 12 years because of sensorineural hearing loss. Transthoracic echocardiography revealed reduced left ventricular ejection fraction (26%), with increased thickness and unusual texture of the myocardium. The absence of abnormal findings on serum and urine protein electrophoresis suggested that light-chain amyloidosis was unlikely. In addition, 99mTc-3,3-diphosphono-1,2-propanodicarboxylic acid scintigraphy revealed no definite uptake in the myocardium. Endomyocardial biopsy revealed a hypertrophy of myocytes in haematoxylin-eosin staining, and electron microscopy revealed a disarrangement of mitochondrial cristae, which were suggestive of mitochondrial cardiomyopathy. A mtDNA test detected the m.3243A > G mutation in the MT-TL1 gene. According to these findings, MELAS syndrome was the most probable diagnosis despite the absence of common symptoms such as stroke-like episodes or lactic acidosis. Discussion: The patient had progressed to heart failure with reduced ejection fraction 24 years after the first cardiac manifestation. An identification of the mutation in the MT-TL1 gene, indicative of MELAS syndrome, enabled the diagnosis of MELAS syndrome without typical manifestations. Keywords: Atrioventricular block; Cardiomyopathy; Case report; Heart failure with reduced ejection fraction; MELAS syndrome; Mitochondrial disease.ope

Somatic mosaic truncating mutations of PPM1D in blood can result from expansion of a mutant clone under selective pressure of chemotherapy

BACKGROUND: PPM1D (Protein phosphatase magnesium-dependent 1δ) is known as a damage response regulator, a part of the p53 negative feedback loop. Truncating mutations of PPM1D, resulting in overexpression, are frequently found in the blood of patients with breast or ovarian cancer. To identify whether the PPM1D mutation predisposes patients to such cancers or if it results from the cancer and therapy, somatic PPM1D mutations in association with previous cancer and chemotherapy need to be explored. METHODS: We performed next-generation sequencing (NGS) analysis of blood samples from patients suspected to have hereditary cancer. We grouped the patients according to their diagnoses and history of chemotherapy. For the patients with PPM1D mutations in blood, tumor tissue specimens were examined for the PPM1D mutation using conventional sequencing. RESULTS: A total of 1,195 patients, including 719 patients with breast cancer and 240 with ovarian cancer, were tested, and four (~0.3%) had the truncating mutation in PPM1D. All truncating mutations were in exon 6, in mosaic form, with a mean allele fraction of 11.15%. While 395 out of the 1,195 patients had undergone chemotherapy, the four with the truncating mutation had a history of cisplatin-based chemotherapy. No corresponding mutations were identified in the tumor tissues. CONCLUSIONS: We investigated the frequency of the somatic mosaic PPM1D mutation, in patients with breast or ovarian cancer, which is suggested to be low and related to a history of cisplatin-based chemotherapy. It may be a marker of previous exposure to selective pressure for cells with an impaired DNA damage response.ope

Germline Mutations Related to Primary Hyperparathyroidism Identified by Next-Generation Sequencing

Primary hyperparathyroidism (PHPT) is characterized by overproduction of parathyroid hormone and subsequent hypercalcemia. Approximately 10% of PHPT cases are hereditary, and several genes, such as MEN1, RET, CASR, and CDC73, are responsible for the familial forms of PHPT. However, other genetic mutations involved in the etiology of PHPT are largely unknown. In this study, we identified genetic variants that might be responsible for PHPT, including familial PHPT, benign sporadic PHPT, and sporadic parathyroid cancer, using next-generation sequencing (NGS). A total of 107 patients with PHPT who underwent NGS from 2017 to 2021 at Severance Hospital were enrolled. We reviewed the pathogenic variants, likely pathogenic variants, and variants of uncertain significance (VUS) according to the American College of Medical Genetics and Genomics and the Association for Molecular Pathology criteria. Of the 107 patients (mean age: 47.6 ± 16.1 years, women 73.8%), 12 patients were diagnosed with familial PHPT, 13 with parathyroid cancer, and 82 with benign sporadic PHPT. Using NGS, we identified three pathogenic variants in two genes (CDC73 and MEN1), 10 likely pathogenic variants in six genes (CASR, CDC73, LRP5, MEN1, SDHA, and VHL), and 39 non-synonymous VUS variants that could be related to parathyroid disease. Interestingly, we identified one GCM2 variant (c.1162A>G [p.Lys388Glu]) and five APC variants that were previously reported in familial isolated hyperparathyroidism, benign sporadic PHPT, and parathyroid cancer. We also analyzed the characteristics of subjects with positive genetic test results (pathogenic or likely pathogenic variants), and 76.9% of them had at least one of the following features: 1) age < 40 years, 2) family history of PHPT, 3) multiglandular PHPT, or 4) recurrent PHPT. In this study, we analyzed the NGS data of patients with PHPT and observed variants that could possibly be related to PHPT pathogenesis. NGS screening for selected patients with PHPT might help in the diagnosis and management of the disease.ope

Comparative Analysis of the Molecular Characteristics of Group B Streptococcus Isolates Collected from Pregnant Korean Women Using Whole-genome Sequencing

Background: The incidence of early- and late-onset sepsis and meningitis in neonates due to maternal rectovaginal group B Streptococcus (GBS) colonization may differ with serotype distribution and clonal complex (CC). CC17 strains are associated with hypervirulence and poor disease outcomes. GBS serotypes are distinguished based on the polysaccharide capsule, the most important virulence factor. We determined the sequence type distribution of GBS isolates from pregnant women in Korea and validated whole-genome sequencing (WGS)-based prediction of antimicrobial susceptibility and capsular serotypes in GBS isolates. Methods: Seventy-five GBS isolates collected from pregnant Korean women visiting Wonju Severance Christian Hospital, Wonju, Korea between 2017 and 2019 were subjected to WGS using the NovaSeq 6000 system (Illumina, San Diego, CA, USA). Multilocus sequence types, serotypes, antimicrobial resistance genes, and hemolysin operon mutations were determined by WGS, and the latter three were compared with the results of conventional phenotypic methods. Results: The predominant lineage was CC1 (37.3%), followed by CC19 (32.0%), CC12 (17.3%), and CC17 (4.0%). All isolates were cps typeable (100%, (75/75), and 89.3% of cps genotypes (67/75) were concordant with serotypes obtained using latex agglutination. The cps genotypes of the 75 isolates were serotypes III (24.0%), V (22.7%), and VIII (17.3%). All isolates harboring intact ermB and tet were non-susceptible to erythromycin and tetracycline, respectively. Three non-hemolytic strains had 1-bp frameshift insertions in cylE. Conclusions: The low prevalence of CC17 GBS colonization may explain the low frequency of neonatal GBS infections. WGS is a useful tool for simultaneous genotyping and antimicrobial resistance determination.ope

Precision Medicine through Next-Generation Sequencing in Inherited Eye Diseases in a Korean Cohort

In this study, we investigated medically or surgically actionable genes in inherited eye disease, based on clinical phenotype and genomic data. This retrospective consecutive case series included 149 patients with inherited eye diseases, seen by a single pediatric ophthalmologist, who underwent genetic testing between 1 March 2017 and 28 February 2018. Variants were detected using a target enrichment panel of 429 genes and known deep intronic variants associated with inherited eye disease. Among 149 patients, 38 (25.5%) had a family history, and this cohort includes heterogeneous phenotype including anterior segment dysgenesis, congenital cataract, infantile nystagmus syndrome, optic atrophy, and retinal dystrophy. Overall, 90 patients (60.4%) received a definite molecular diagnosis. Overall, NGS-guided precision care was provided to 8 patients (5.4%). The precision care included cryotherapy to prevent retinal detachment in COL2A1 Stickler syndrome, osteoporosis management in patients with LRP5-associated familial exudative vitreoretinopathy, and avoidance of unnecessary phlebotomy in hyperferritinemia-cataract syndrome. A revision of the initial clinical diagnosis was made in 22 patients (14.8%). Unexpected multi-gene deletions and dual diagnosis were noted in 4 patients (2.7%). We found that precision medical or surgical managements were provided for 8 of 149 patients (5.4%), and multiple locus variants were found in 2.7% of cases. These findings are important because individualized management of inherited eye diseases can be achieved through genetic testing.ope