Becoming a doctor: using social constructivism and situated learning to understand the clinical clerkship experiences of undergraduate medical students.

BACKGROUND: Despite the emphasis on the uniqueness and educational importance of clinical clerkships in medical education, there is a lack of deep understanding of their educational process and outcomes. Especially due to an inherent trait of clinical clerkships which requires participation in the workplace outside the classroom, it is difficult to fully comprehend their educational potential using traditional learning perspectives such as imbibing outside knowledge. Accordingly, this study aims to explore the experiences of a rotation-based clerkship of medical school students from the perspective of social constructivism of learning, which can empirically examine what and how medical students learn during clinical clerkship in South Korea. By providing an insight into the workings of the clerkship process, this study contributes to a better understanding of how a learning-friendly environment can be cultivated at clinical clerkships. METHODS: The study utilized a basic qualitative study to understand what and how medical students learn during their clinical clerkships. Semi-structured, in-depth individual interviews were conducted with eight sixth-graders who had experienced a two-year clerkship at Ajou University Medical School. Data were analyzed based on Lave and Wenger's situated learning theory and Wenger's social theory in learning. RESULTS: We found that the medical students had developed different aspects of their professional identities such as values, functionality, career decisions, sociality, and situating during their clinical clerkships. Further, professional identity was formed through a combination of participation and reification-the processes involved in the negotiation of meaning. This combination was facilitated by the students' first experience and relationships with professors, classmates, and patients. Finally, non-learning occurred in the context of over-participation (learning anxiety and alienation) or over-reification (evaluation and e-portfolio). CONCLUSIONS: This study revealed five sub-professional identities and their formation process from the learners' perspective, thereby uncovering the unique learning characteristics and advantages of rotated-based clerkship and contributing to a further understanding of how gradual improvements can be made to the traditional clerkship education of medical students.

Changes in the Incidence of Immune Thrombocytopenia in the Coronavirus Disease 2019 Era: A Nationwide Observational Study in Korea.

Purpose: We investigated whether nonpharmaceutical interventions (NPI) to reduce the spread of coronavirus disease 2019 (COVID-19) was associated with a change in the incidence of immune thrombocytopenia (ITP). Patients and Methods: Using the Korean Health Insurance Review and Assessment Services (HIRA) database, individuals newly diagnosed with ITP between January 2015 and December 2020 were identified. The NPI period was defined as February 2020 to December 2020. The ITP incidence in the NPI period was compared with the mean annual incidence during the same months in the pre-NPI period and the incidence predicted by the autoregressive integrated moving average model. Results: In total, 25,723 patients were identified, and the overall annual incidence of ITP was 8.28 per 100,000 persons ([95% confidence interval (CI): 8.18-8.39]. The ITP incidence in the NPI period was 6.60 per 100,000 person-years (95% CI: 6.37-6.85), 0.77 times (95% CI: 0.74-0.80) lower than that during the pre-NPI period [8.62/100,000 (95% CI: 8.50-8.74)]. With the exception for patients aged ≥70 years, the ITP incidence was significantly lower in the NPI period than in the pre-NPI period. The most significant decline in the ITP incidence during the NPI period was observed in the 0-9 years age group [25.76/100,000 vs 14.01/100,000, P <0.001; incidence rate ratio (IRR): 0.54 (95% CI: 0.51-0.58)]. The intravenous immunoglobulin-treated ITP incidence in the NPI period was 1.69/100,000 (95% CI: 1.58-1.81), 0.79 times (95% CI: 0.73-0.85) lower than that in the pre-NPI period 2.15/100,000 (95% CI: 2.09-2.21)]. The incidence of steroid-treated ITP was lower in the NPI period than in the pre-NPI period (2.73/100,000 vs 2.2/100,000, P <0.001), with an IRR of 0.80 (95% CI: 0.76-0.83). Conclusion: This nationwide study revealed a significant decrease in ITP incidence, particularly among children, after the implementation of NPI.

Twenty-Five Year Trend Change in the Etiology of Pediatric Invasive Bacterial Infections in Korea, 1996-2020.

BACKGROUND: The coronavirus disease-2019 (COVID-19) pandemic has contributed to the change in the epidemiology of many infectious diseases. This study aimed to establish the pre-pandemic epidemiology of pediatric invasive bacterial infection (IBI). METHODS: A retrospective multicenter-based surveillance for pediatric IBIs has been maintained from 1996 to 2020 in Korea. IBIs caused by eight bacteria (Streptococcus pneumoniae, Haemophilus influenzae, Neisseria meningitidis, Staphylococcus aureus, Streptococcus agalactiae, Streptococcus pyogenes, Listeria monocytogenes, and Salmonella species) in immunocompetent children > 3 months of age were collected at 29 centers. The annual trend in the proportion of IBIs by each pathogen was analyzed. RESULTS: A total of 2,195 episodes were identified during the 25-year period between 1996 and 2020. S. pneumoniae (42.4%), S. aureus (22.1%), and Salmonella species (21.0%) were common in children 3 to 59 months of age. In children ≥ 5 years of age, S. aureus (58.1%), followed by Salmonella species (14.8%) and S. pneumoniae (12.2%) were common. Excluding the year 2020, there was a trend toward a decrease in the relative proportions of S. pneumoniae (rs = -0.430, P = 0.036), H. influenzae (rs = -0.922, P < 0.001), while trend toward an increase in the relative proportion of S. aureus (rs = 0.850, P < 0.001), S. agalactiae (rs = 0.615, P = 0.001), and S. pyogenes (rs = 0.554, P = 0.005). CONCLUSION: In the proportion of IBIs over a 24-year period between 1996 and 2019, we observed a decreasing trend for S. pneumoniae and H. influenzae and an increasing trend for S. aureus, S. agalactiae, and S. pyogenes in children > 3 months of age. These findings can be used as the baseline data to navigate the trend in the epidemiology of pediatric IBI in the post COVID-19 era.

Changes in Etiology of Invasive Bacterial Infections in Infants Under 3 Months of Age in Korea, 2006-2020.

OBJECTIVES: Invasive bacterial infection (IBI) causes a significant burden in infants. In this study, we analyzed changes in epidemiology of IBI among infants in Korea. METHODS: A retrospective multicenter-based surveillance for IBIs in infants <3 months of age was performed during 2006-2020. Cases were classified as an early-onset disease (EOD) (0-6 days) or late-onset disease (LOD) (7-89 days). The temporal trend change in proportion of pathogens was analyzed. RESULTS: Among 1545 cases, the median age was 28 days (IQR: 12, 53) and EOD accounted for 17.7%. Among pathogens, S. agalactiae (40.4%), E. coli (38.5%), and S. aureus (17.8%) were the most common and attributed for 96.7%. Among EOD (n = 274), S. agalactiae (45.6%), S. aureus (31.4%), E. coli (17.2%) and L. monocytogenes (2.9%) were most common. Among LOD (n = 1274), E. coli (43.1%), S. agalactiae (39.3%), S. aureus (14.9%) and S. pneumoniae (1.3%) were most common. In the trend analysis, the proportion of S. aureus (r s = -0.850, P < 0.01) decreased significantly, while that of S. agalactiae increased (r s = 0.781, P < 0.01). CONCLUSION: During 2006-2020, among IBI in infants <3 months of age, S. agalactiae, E. coli, and S. aureus were most common and an increasing trend of S. agalactiae was observed.

Effect of a Regional Outbreak of Coronavirus Disease 2019 on Kawasaki Disease in Korea.

Purpose: The association between coronavirus disease 2019 (COVID-19) and Kawasaki disease (KD) remains controversial. Prior to the nationwide epidemic of COVID-19, there was a unique, large-scale, regional outbreak in Daegu and Gyeonsangbuk-do (DG) in Korea in the spring of 2020. We evaluated the impact of COVID-19 on KD by comparing the characteristics of KD incidence between epidemic and non-epidemic regions in Korea. Patients and Methods: We analyzed nationwide Health Insurance Review and Assessment (HIRA) data to estimate KD incidence from February 2019 to July 2020. Patients below 18 years who were admitted with KD and administered both intravenous immunoglobulin and aspirin (ICD-10 code M303 for KD) were included in the study. We compared the incidence of KD in DG and other regions by analyzing the period-specific incidence from February to May before and after the COVID-19 era. Results: A total of 4461 patients were identified to have KD nationwide from February 2019 to July 2020. The nationwide incidence of KD was significantly reduced during this period compared with the period from February 2018 to July 2019 (p < 0.001). In the DG region, within the 0-4-years age group, there was no significant difference in the incidence of KD between periods (p = 0.714). In the 5-9 years age group, a significant decrease in KD incidence was observed in the DG region and all other regions from February 2019 to July 2020. Conclusion: There was a significant decrease in nationwide KD incidence during and until 2 months after the local epidemic in Korea. However, no significant decrease in KD incidence was observed in the 0-4 years age group in the DG region where the local COVID-19 outbreak occurred. A larger study is necessary to determine the correlation between KD in this age group and the COVID-19 outbreak.

Risk Assessment of Recurrence and Autoimmune Disorders in Kikuchi Disease.

PURPOSE: Kikuchi disease (KD) is typically a benign disease. Recent studies reporting recurrence or serious cases suggest a possible association of KD with systemic autoimmune disorders. We performed a long-term analysis of the characteristics of KD in patients of all ages and assessed KD recurrence or progress to systemic autoimmune disorders. PATIENTS AND METHODS: Electronic medical records of patients diagnosed with KD between April 1995 and May 2017 were reviewed for clinical and laboratory manifestations. RESULTS: In total, 480 patients were confirmed to have KD based on histopathology findings. The mean age at KD diagnosis was 24.4 years. Recurrence occurred in 11.3% of patients; 2.7% developed autoimmune diseases after KD diagnosis. Patients who experienced recurrence had more extranodal symptoms, lymphopenia, and a longer lymphopenia-recovery duration. Patients who developed autoimmune diseases after KD were more likely to have extranodal symptoms, KD recurrence, and anti-nuclear antibody positivity. CONCLUSION: KD patients with risk factors need to be followed-up for KD recurrence and the development of systemic autoimmune diseases.

Diagnostic performance of contrast-enhanced ultrasound for acute pyelonephritis in children.

The objective of our study was to evaluate the performance of renal contrast-enhanced ultrasound (CEUS) against the 99m-labeled dimercaptosuccinic acid (DMSA) scan and computed tomography (CT) in children for the diagnosis of acute pyelonephritis. We included children who underwent both renal CEUS and the DMSA scan or CT. A total of 33 children (21 males and 12 females, mean age 26 ± 36 months) were included. Using the DMSA scan as the reference standard, the sensitivity, specificity, positive predictive value, and negative predictive value of CEUS was 86.8%, 71.4%, 80.5%, and 80.0%, respectively. When CT was used as the reference standard, the sensitivity, specificity, positive predictive value, and negative predictive value of CEUS was 87.5%, 80.0%, 87.5%, and 80.0%, respectively. The diagnostic accuracy of CEUS for the diagnosis of acute pyelonephritis was 80.3% and 84.6% compared to the DMSA scan and CT, respectively. Inter-observer (kappa = 0.54) and intra-observer agreement (kappa = 0.59) for renal CEUS was moderate. In conclusion, CEUS had good diagnostic accuracy for diagnosing acute pyelonephritis with moderate inter- and intra-observer agreement. As CEUS does not require radiation or sedation, it could play an important role in the future when diagnosing acute pyelonephritis in children.

Vancomycin Dosage and Its Association with Clinical Outcomes in Pediatric Patients with Gram-Positive Bacterial Infections.

AIM: The aim of this study was to evaluate whether vancomycin trough concentrations at initial steady state are associated with clinical and microbiological outcomes along with vancomycin-related nephrotoxicity in pediatric patients with Gram-positive bacterial (GPB) infections. METHODS: A retrospective cohort study of pediatric patients who received vancomycin for ≥72 hours during 2008-2016 was conducted. Study patients were divided into three cohorts in accordance with their first trough levels at steady state: <5 mg/L (lower-trough), 5-10 mg/L (low-trough), and >10 mg/L (high-trough; reference) cohorts. RESULTS: Of the 201 patients eligible for study inclusion, 60 patients in the lower- and low-trough cohorts, respectively, were idect 3ntified via propensity score matching and analyzed against 30 high-trough patients in each comparison pair (neonates were excluded due to small sample size). Lower-trough patients were at a greater risk for prolonged therapy, retreatment, and dose adjustment than high-trough patients. Final steady-state troughs remained substantially lower in both the lower- and low-trough cohorts (p<0.001 and p=0.005, respectively), despite greater dose up-titration in the lower-trough cohort and percent change in daily dose in both the lower- and low-trough cohorts than in the high-trough cohort (p<0.001 for all). Clinical cure and death risk, along with the risks of isolation of resistant strains and renal events, were not significantly different between cohorts in both comparison pairs. CONCLUSION: Vancomycin troughs of <5 mg/L at initial steady state were associated with significantly compromised clinical outcomes in terms of risk of therapy prolongation, retreatment, and aggressive dose up-titration, compared to >10 mg/L troughs in pediatric patients with GPB infections.

The First Reported Case of Infant Botulism in Korea: Treatable Infantile Neuromuscular Disease.

Botulism is a rare neuromuscular disorder caused by neurotoxins produced by Clostridium botulinum. The diagnosis of infant botulism may be obscured or delayed, as its presentation is similar to that of infantile neuromuscular disorders. We report the first Korean case of infant botulism in an acute progressive floppy infant with poor sucking and a weak cry. No abnormalities were found in all blood, cerebrospinal fluid, genetic test, nerve conduction study, and imaging studies. A stool-toxin test was finally performed under suspicion of infant botulism, and the result was positive. The patient was immediately treated with heptavalent botulism antitoxin. Follow-up after 3 months showed normal development with a complete resolution of all symptoms. Therefore, clinical suspicion of infant botulism, which is a treatable infantile neuromuscular disease, is essential for early diagnosis and prompt treatment in the differential diagnosis of a floppy infant.

Incidence of Influenza Among Childhood Cancer Survivors in South Korea: A Population-based Retrospective Analysis.

BACKGROUND/AIM: We quantified the incidence, and identified risk factors for influenza infection among childhood cancer survivors in South Korea, an at-risk population. PATIENTS AND METHODS: Nationwide health insurance claims data were used to assess the frequency of influenza among childhood cancer survivors (aged <20 years) diagnosed between January 2009 and April 2016. A multivariable logistic regression was constructed to identify risk factors for influenza. RESULTS: Of 6,457 children cancer survivors, 1,704 (27.0%) were diagnosed with influenza. Influenza was common in children <5 years old and infections were highest between late October and April. Over 60% of influenza treatment claims came from private clinics. Risk factors for influenza included age <9 years. CONCLUSION: Childhood cancer survivors are particularly at-risk for influenza infection during the traditional influenza season. Identifying risks for influenza infection will help to establish countermeasures for reducing the influenza infections in at-risk cancer surviving children.

Atypical Presentation of Chronic Granulomatous Disease in a Neonate with a Pulmonary Granuloma Mimicking a Tumor: A Case Report.

Chronic granulomatous disease (CGD) is an uncommon primary immune deficiency caused by phagocytes defective in oxygen metabolite production. It results in recurrent bacterial or fungal infections. Herein, we present a case of CGD with a large pulmonary granuloma in a neonate and review the imaging findings. The patient was a 24-day-old neonate admitted to the hospital with fever. A round opacified lesion was identified on the chest radiograph. Subsequent CT and MRI revealed a round mass with heterogeneous enhancement in the right lower lobe. There were foci of diffusion restriction in the mass. Surgical biopsy of the mass revealed chronic granuloma. Finally, the neonate was diagnosed with CGD caused by mutation of the gp91phox gene. Herein, we present the clinical and imaging findings of this unusual case of CGD.

Effect of Tissue Transglutaminase on Steroid Resistance in T-Cell Acute Lymphoblastic Leukemia.

AIM: To improve survival in patients with glucocorticoid-resistant T-cell acute lymphoblastic leukemia (T-ALL), it is critical to develop new therapeutic strategies to overcome steroid resistance. MATERIALS AND METHODS: Biochemical and molecular methodologies were used to evaluate whether tissue transglutaminase (TG2) confers steroid resistance in T-ALL. RESULTS: T-ALL cells were found to express elevated levels of TG2. Models of steroid-adapted subclones of T-ALL cell lines which were notably less sensitive to steroids than the parental cells. The steroid-adapted subclones showed increased TG2 expression and nuclear factor-κB (NF-κB) activity compared to T-ALL parental cells. Inhibition of TG2 suppressed steroid resistance and improved steroid cytotoxicity in steroid-adapted subclones of T-ALL in association with reduced NF-κB activity. CONCLUSION: TG2 may serve as a new target to overcome steroid resistance in T-ALL.

Mussel-inspired enzyme immobilization and dual real-time compensation algorithms for durable and accurate continuous glucose monitoring.

Blood glucose sensing is very important for diabetic management. It is shifting towards a continuous glucose monitoring because such a system can alleviate patient suffering and provide a large number of glucose measurements. Here, we proposed a novel approach for the development of durable and accurate enzymatic continuous glucose monitoring system (CGMS). For the long-term durable and selective immobilization of glucose oxidase on a microneedle electrode, a biocompatible engineered mussel adhesive protein was employed through efficient electrochemical oxidation strategy. For the accurate performance in in vivo environments, we also suggested dual real-time compensated algorithms to cover both temperature and time-lag differences. After pre-clinical and pilot-clinical evaluations, we confirmed that our proposed CGMS has an outstanding performance compared with various commercially available continuous systems and achieves comparable performance to disposable glucose sensors.

Fluoroscopic evaluation of the influence of needle gauge on epidural spread in caudal block.

Caudal block has limited injectate distribution to the desired lumbar level due to the relatively long distance from the injection site and reduction in the volume of injectate due to leakage into the sacral foramen. The objective of this study was to investigate the influence of needle gauge on fluoroscopic epidural spread and to assess the correlation between the spread level and analgesic efficacy in patients undergoing caudal block. We retrospectively analyzed data from 80 patients who received caudal block for lower back and radicular pain. We categorized patients based on the epidural needle gauge used into group A (23 gauge), group B (20 gauge), and group C (17 gauge). Fluoroscopic image of the final level of contrast injected through the caudal needle and pain scores before the block and 30 minutes after the block recorded using a numerical rating scale, were evaluated. Of the 80 patients assessed for eligibility, 7 were excluded. Thus, a total of 73 patients were finally analyzed. Age, sex, body mass index, diagnosis, lesion level, lesion severity, and duration of pain did not differ among the 3 groups. All patients showed cephalic spread of contrast. Contrast spread beyond L5 was seen in 26.9% of patients in group A, 41.7% in group B, 39.1% in group C, and 35.6% overall; there was no significant difference among the groups (P = .517). Analgesic efficacy was not significantly different among the groups (P = .336). The needle gauge did not influence the level of epidural spread or analgesic efficacy in caudal block.

Molecular diagnosis of hereditary spherocytosis by multi-gene target sequencing in Korea: matching with osmotic fragility test and presence of spherocyte.

BACKGROUND: Current diagnostic tests for hereditary spherocytosis (HS) focus on the detection of hemolysis or indirectly assessing defects of membrane protein, whereas direct methods to detect protein defects are complicated and difficult to implement. In the present study, we investigated the patterns of genetic variation associated with HS among patients clinically diagnosed with HS. METHODS: Multi-gene targeted sequencing of 43 genes (17 RBC membrane protein-encoding genes, 20 RBC enzyme-encoding genes, and six additional genes for the differential diagnosis) was performed using the Illumina HiSeq platform. RESULTS: Among 59 patients with HS, 50 (84.7%) had one or more significant variants in a RBC membrane protein-encoding genes. A total of 54 significant variants including 46 novel mutations were detected in six RBC membrane protein-encoding genes, with the highest number of variants found in SPTB (n = 28), and followed by ANK1 (n = 19), SLC4A1 (n = 3), SPTA1 (n = 2), EPB41 (n = 1), and EPB42 (n = 1). Concurrent mutations of genes encoding RBC enzymes (ALDOB, GAPDH, and GSR) were detected in three patients. UGT1A1 mutations were present in 24 patients (40.7%). Positive rate of osmotic fragility test was 86.8% among patients harboring HS-related gene mutations. CONCLUSIONS: This constitutes the first large-scaled genetic study of Korean patients with HS. We demonstrated that multi-gene target sequencing is sensitive and feasible that can be used as a powerful tool for diagnosing HS. Considering the discrepancies of clinical and molecular diagnoses of HS, our findings suggest that molecular genetic analysis is required for accurate diagnosis of HS.

Increasing Prevalence of Group III Penicillin-Binding Protein 3 Mutations Conferring High-Level Resistance to Beta-Lactams Among Nontypeable Haemophilus influenzae Isolates from Children in Korea.

This study investigated the roles of ß-lactamase and penicillin-binding protein 3 (PBP3) alterations in the development of recent antimicrobial resistance in nontypeable Haemophilus influenzae (NTHi) isolated from Korean children. Nasopharyngeal NTHi isolates from children at a tertiary children's hospital were tested for antimicrobial susceptibility using E-test. ß-lactamase production was screened by the paper disc test, and polymerase chain reaction amplification of blaTEM and blaROB-1 was performed. The ftsI gene was amplified to identify PBP3 alteration. Of the 53 NTHi isolates, 69.8% were ampicillin nonsusceptible. The nonsusceptibility rates for cefaclor were 81.1%, cefpodoxime 69.8%, and amoxicillin/clavulanate 32.1%. About 60.3% and 32.1% of the isolates were genetically ß-lactamase-nonproducing ampicillin-resistant (gBLNAR) and genetically ß-lactamase-producing amoxicillin/clavulanate-resistant (gBLPACR) strains, respectively. Group III amino acid substitutions comprised 65.6% of the gBLNAR strains and 70.6% of the gBLPACR strains. MIC50 for amoxicillin/clavulanate, cefaclor, cefuroxime, cefpodoxime, and cefixime were more than 2-80 times higher in the gBLNAR and gBLPACR strains compared with gBLPAR strains. Group III gBLNAR strains had significantly higher ampicillin, amoxicillin/clavulanate, cefpodoxime, and cefixime minimum inhibitory concentrations than group II strains. Group III gBLNAR and gBLPACR NTHi strains are highly prevalent in Korea, raising the alarm about increasing ß-lactam resistance in NTHi.

B7­H1­mediated immunosuppressive properties in human mesenchymal stem cells are mediated by STAT­1 and not PI3K/Akt signaling.

Mesenchymal stem cells (MSCs), derived from either bone marrow (BM) or Wharton's jelly (WJ), inhibit the proliferation of activated T cells, and interferon (IFN)­Î³ serves an important role in this process. This process is B7­homolog (H)1­dependent during cell contact inhibition. However, the signaling pathway involved in B7­H1 expression in MSCs remains largely undefined. The present study demonstrated activation of B7­H1 by engaging signal transducer and activator of transcription (STAT)­1 signaling in MSCs. Human BM­ and WJ­MSCs were isolated and cultured. The immunosuppressive effect of BM­ and WJ­MSCs on phytohemagglutinin (PHA)­induced T cell proliferation was compared using direct and indirect co­culture systems. B7­H1 expression on BM­ and WJ­MSCs was detected by flow cytometry. Small interfering (si)RNA was used to knock down the expression of STAT­1. The inhibitory effect of MSCs on T lymphocytes was observed using PHA­induced T cell proliferation assays. IFN­Î³­induced B7­H1 expression on human BM­ and WJ­MSCs increased in a time­dependent manner. Furthermore, the inhibitory effect of MSCs on T cell proliferation was be restored when an anti­B7­H1 monoclonal antibody was used. When STAT­1 signaling was inhibited by siRNA, B7­H1 expression on IFN­Î³­treated MSCs decreased and T cell proliferation was restored; however, the expression of B7­H1 did not alter upon treatment with a phosphatidylinositol­3­kinase (PI3K) inhibitor (LY294002). These results demonstrated that the IFN­Î³­induced immunosuppressive properties of B7­H1 in human BM­ and WJ­MSCs were mediated by STAT­1 signaling, and not by PI3K/RAC­α serine/threonine­protein kinase signaling. Understanding the intracellular mechanisms underlying IFN­Î³­induced expression of B7­H1 in MSCs may ultimately lead to an improved understanding of MSCs and provide insight into their use as cell therapy agents.

Re-evaluation of DNA Index as a Prognostic Factor in Children with Precursor B Cell Acute Lymphoblastic Leukemia.

PURPOSE: We aimed to investigate the prognostic value of DNA index (DI) in children with precursor B cell acute lymphoblastic lymphoma (pre-B ALL). MATERIALS AND METHODS: From January 2003 to December 2014, 72 children diagnosed with pre-B ALL were analyzed. We analyzed the prognostic value of DI and its relations with other prognostic factors. RESULTS: The DI cut-point of 1.16 did not discriminate significantly the groups between high and low survivals (DI≥1.16 versus <1.16; 5-year OS, 90.5% vs. 82.8%, p=0.665). We explored the survivals according to the level of DI (<1.00, 1.00, 1.01-1.30, 1.31-1.60, 1.61-1.90, and >1.90), and the survival of children with a DI between 1.00-1.90 were significantly higher than that of children with DI of <1.00 or >1.90 (5-year OS, 90.6% vs. 50.0%, p<0.001). CONCLUSIONS: The DI of 1.16 was not a significant cut-point discriminating the risk group in children with pre-B ALL. However, the DI divided by specific ranges of values remained an independent prognostic factor. Further studies are warranted to re-evaluate the prognostic value and cut-point of DI in children treated with recent treatment protocols.

Esthesioneuroblastoma in a boy with 47, XYY karyotype.

Neuroblastomas are sometimes associated with abnormal constitutional karyotypes, but the XYY karyotype has been rarely described in neuroblastomas. Here, we report a case of an esthesioneuroblastoma in a boy with a 47, XYY karyotype. A 6-year-old boy was admitted to our hospital because of nasal obstruction and palpable cervical lymph node, which he first noticed several days previously. A polypoid mass in the right nasal cavity was detected through sinuscopy. Biopsy of the right nasal polyp was performed. Based on the result, the patient was diagnosed with a high-grade esthesioneuroblastoma. Nuclear imaging revealed increased uptake in both the right posterior nasal cavity and the right cervical IB-II space, suggesting metastatic lymph nodes. Cytogenetic analysis revealed a 47, XYY karyotype. Twelve courses of concurrent chemotherapy were administered. Three years after the completion of chemotherapy, the patient had had no disease recurrence. He manifested behavioral violence and temper tantrums, so we started methylphenidate for correction of the behavior.

Emergence of antibiotic-resistant non-vaccine serotype pneumococci in nasopharyngeal carriage in children after the use of extended-valency pneumococcal conjugate vaccines in Korea.

BACKGROUND: This study was performed to assess the serotype distribution and antibiotic nonsusceptibility of pneumococcal carriage isolates from children in Korea following the introduction of extended-valency pneumococcal conjugate vaccines (PCVs). METHODS: From April to June 2014, nasopharyngeal swabs were collected from children who were attending daycare centers in Korea. The collection was conducted in accordance with the World Health Organization Pneumococcal Carriage Working Group standards. Isolates were identified based on colony morphology, the presence of alpha-hemolysis, and inhibition by optochin test. Serotype was determined by Quellung reaction and sequencing analysis (for serogroup 6). The E-test was performed to determine antibiotic susceptibility. RESULTS: A total of 267 pneumococcal isolates were collected from 734 children. Non-PCV13 serotypes accounted for 88.3% and 23A (12.6%), 15B (10.4%), and 15C (9.5%) were most common. Younger age was associated with higher carriage (65.6% vs. 31.2%, P<0.001), while completion of PCV vaccination was associated with lower carriage caused by PCV13 serotypes (7.4% vs. 20.8%, P=0.007). Overall, nonsusceptibility rates were 86.0% to penicillin and 90.5% to erythromycin, with a multidrug resistance rate of 81.5%. Among penicillin-nonsusceptible isolates, those caused by PCV13 serotypes were 11% and non-PCV13 serotypes were 89%. Frequent non-PCV13 serotypes (23A, 15B, and 15C) were all nonsusceptible to both penicillin and erythromycin except one. CONCLUSION: High rates of carriage caused by non-PCV13 serotypes such as 23A, 15B, and 15C that show nonsusceptibilities to penicillin and erythromycin were noted following the introduction of extended-valency PCVs in Korea.