Publications by authors named "Jin Han Kang"

141 Publications

Effects of nasopharyngeal microbiota in respiratory infections and allergies.

Clin Exp Pediatr 2021 Apr 15. Epub 2021 Apr 15.

Division of Pediatric Infectious Diseases, Departments of Pediatrics, College of Medicine, The Catholic University of Korea, Seoul, Korea.

The human microbiome, which consists of a collective cluster of commensal, symbiotic, and pathogenic microorganisms living in the human body, plays a key role in host health and immunity. The human nasal cavity harbors commensal bacteria that suppress the colonization of opportunistic pathogens. However, dysbiosis of the nasal microbial community is associated with many diseases, such as acute respiratory infections including otitis media, sinusitis and bronchitis and allergic respiratory diseases including asthma. The nasopharyngeal acquisition of pneumococcus, which exists as a pathobiont in the nasal cavity, is the initial step in virtually all pneumococcal diseases. Although the factors influencing nasal colonization and elimination are not fully understood, the adhesion of opportunistic pathogens to nasopharyngeal mucosa receptors and the eliciting of immune responses in the host are implicated in addition to bacterial microbiota properties and colonization resistance dynamics. Probiotics or synbiotic interventions may show promising and effective roles in the adjunctive treatment of dysbiosis; however, more studies are needed to characterize how these interventions can be applied in clinical practice in the future.
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http://dx.doi.org/10.3345/cep.2020.01452DOI Listing
April 2021

Active-controlled phase III study of an egg-cultivated quadrivalent inactivated split-virion influenza vaccine (GC3110A) in healthy Korean children aged 6-35 months.

Vaccine 2021 Apr 16;39(15):2103-2109. Epub 2021 Mar 16.

Department of Pediatrics, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea; Vaccine Bio Research Institute, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea. Electronic address:

The inactivated trivalent influenza vaccine (TIV) offers limited protection when two influenza B lineages co-circulate or when there is a vaccine mismatch (i.e., discordance in the predominant circulating B strain and WHO-recommended B strain). Inactivated quadrivalent influenza vaccine (QIV) may reduce the burden of influenza. Here, we report the results of a phase 3 clinical trial that evaluated the immunogenicity and safety of a novel QIV, GC3110A, in Korean children aged 6-35 months, which has been approved and is currently in use in Korea. The study involved two parts. In Part 1, the safety of GC3110A was evaluated in 10 subjects. After none of the subjects reported grade 3 adverse events (AEs), we proceeded to Part 2. Part 2 was a randomized, double-blind, multicenter phase 3 trial wherein we compared the immunogenicity and safety of GC3110A with those of a licensed control TIV. Immunogenicity was evaluated by measuring hemagglutination inhibition titers. The 200 participants enrolled in Part 2 were randomized in a 4:1 ratio to receive GC3110A or control TIV. The study vaccine group met both primary (i.e., the lower limit of 95% confidence interval [CI] of the seroconversion rate exceeds 40% for four strains) and secondary (i.e., the lower limit of 95% CI of the seroprotection rate exceeds 70% for four strains) immunogenicity endpoints. There was no significant between-group difference in the seroconversion rate, seroprotection rate, and geometric mean titer for the shared strains. However, the study vaccine group demonstrated significantly higher immunity for the additional strain B/Yamagata. In the safety analysis, there was no significant between-group difference in the proportion of participants with solicited local AEs, solicited systemic AEs, and unsolicited AEs. In conclusion, the results indicate that GC3110A has comparable immunogenicity and safety to those of TIV. Clinical Trial Registry Number: NCT03285997.
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http://dx.doi.org/10.1016/j.vaccine.2021.03.005DOI Listing
April 2021

Clinical features and outcomes of influenza by virus type/subtype/lineage in pediatric patients.

Transl Pediatr 2021 Jan;10(1):54-63

Department of Pediatrics, College of Medicine, The Catholic University of Korea, Seoul, Korea.

Background: Recently, four influenza viruses are circulating worldwide: A(H1N1)pdm09, A(H3N2), B/Victoria, and B/Yamagata. However, information on the clinical differences among pediatric patients infected with four recently circulating influenza viruses is sparse.

Methods: Medical records of pediatric patients (<20 years of age) diagnosed with influenza between the 2014-2015 and 2018-2019 influenza seasons were retrospectively reviewed. Clinical features were compared between (I) patients infected with influenza A (FluA) and influenza B (FluB) viruses, (II) patients infected with FluA when A(H1N1)pdm09 and A(H3N2) circulated dominantly, and (III) patients infected with FluB when B/Victoria and B/Yamagata circulated dominantly.

Results: A total of 1,588 patients infected with FluA and 964 patients infected with FluB were included in this study. Patients infected with FluB were older (P<0.001) and more likely to report sore throat (P=0.002) than those infected with FluA. Otherwise, there were no significant differences in the clinical symptoms, diagnoses, and outcomes between patients infected with FluA and FluB. Overall, clinical features of influenza patients were similar regardless of the dominantly circulated subtype and lineage of the virus. In children aged ≤2 years, patients infected with FluB were more like to experience lower respiratory tract infection (P=0.034) and hospitalization (P=0.001) than those infected with FluA.

Conclusions: There were no significant clinical differences among pediatric patients infected with four recently circulating influenza viruses, except that FluB infection tended to be more severe than FluA infection in children aged ≤2 years.
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http://dx.doi.org/10.21037/tp-20-196DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7882295PMC
January 2021

Immunogenicity and safety profiles of a new MAV/06 strain varicella vaccine in healthy children: A multinational, multicenter, randomized, double-blinded, active-controlled phase III study.

Vaccine 2021 Mar 21;39(12):1758-1764. Epub 2021 Feb 21.

Department of Pediatrics, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea; Vaccine Bio Research Institute, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea. Electronic address:

Immunization is the most effective preventive strategy against varicella. While the Oka strain is commonly used for varicella vaccination worldwide, Korea widely uses the MAV/06 strain. A new live attenuated MAV/06 strain varicella vaccine (MG1111), which uses the new cell line Medical Research Council-5 for better viral propagation, was developed. MG1111 was approved by Korean health authorities. Here, we report the results of phase III, randomized, double-blind, multicenter study conducted in Korea and Thailand, which compared the immunogenicity and safety profiles of MG1111 versus the control vaccine, Varivax. In total, 515 healthy children (12 month-12 years) were randomized 1:1 to receive either the MG1111 or control vaccine (MG1111: 258, Control: 257). The seroconversion rate (SCR) and geometric mean titer (GMT) were measured using the fluorescent antibody to membrane antigen (FAMA) test. The MG1111 group achieved a SCR of 97.9% (95% CI: 95.2-99.3) after vaccination. The lower limit of 95% CI for SCR difference (MG1111-Varivax) was -4.0%, which was higher than the specified non-inferiority margin of -10%. Further, the GMT of the MG1111 increased from 2.0 to 74.2 (95% CI: 65.0-84.8) and the lower limits of the 95% CI for post-vaccination GMT ratios (MG1111/Varivax) were 0.55 higher than the specified parameter of 0.5. Therefore, the MG1111 group was not statistically inferior to the control vaccine group in terms of SCR and GMT. Furthermore, the MG1111 and control vaccine groups were not significantly different in the percentage of participants showing adverse events-solicited, local, or systemic during 43-day period of observation and serious adverse events during 6 month of observation. The present results indicate that MG1111was not immunologically inferior to Varivax, and safety profiles of MG1111 are similar to those of Varivax.
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http://dx.doi.org/10.1016/j.vaccine.2021.02.013DOI Listing
March 2021

Impact of Antibiotic Prescribing Patterns on Susceptibilities of Uropathogens in Children below 24 Months Old.

Antibiotics (Basel) 2020 Dec 16;9(12). Epub 2020 Dec 16.

Department of Pediatrics, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea.

Monitoring regional antibiotic resistance patterns of uropathogens are important for deciding suitable empirical antibiotics for urinary tract infections (UTIs) in children. This study aimed to investigate regional differences in antimicrobial susceptibility patterns of and spp. in children below 24 months old, diagnosed with their first episode of UTI, and to find factors associated with an increased risk for UTI caused by extended-spectrum β-lactamase (ESBL)-producing uropathogens. This was a retrospective cohort study of children diagnosed between 2011 and 2017 in four different hospitals located in four different regions of South Korea; regions A, B, C, and D. The government's big data repository was used to acquire data on regional antibiotic prescriptions. The pooled antimicrobial susceptibilities of and spp. ( = 2044) were as follows: ampicillin-sulbactam (61.0%), 3rd generation cephalosporin (3C) (82.8%), and trimethoprim-sulfamethoxazole (72.0%). Multivariate analysis showed that children diagnosed at hospital A (OR, 1.8; 95% confidence interval [CI], 1.2-2.6; = 0.002) and every year that increased in the study period (OR, 1.1; 95% CI, 1.1-1.2; < 0.001) were factors associated with an increased risk for UTIs with ESBL-producers. Regions A and B had significantly higher amounts of oral 3Cs prescribed compared to regions C and D ( = 0.009), which correlate with hospitals in the regions that had higher proportions of UTIs with ESBL-producing uropathogens (A and B vs. C and D, < 0.001). Therefore, children in certain regions are at a higher risk for UTIs caused by ESBL-producers compared to other regions, which correlate with regions that had higher amounts of oral 3Cs prescribed.
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http://dx.doi.org/10.3390/antibiotics9120915DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7767190PMC
December 2020

Recurrent Meningitis Caused by β-Lactamase-Positive Amoxicillin/Clavulanate-Resistant Non-Typeable in a Child with an Inner Ear Malformation: A Case Report.

Infect Chemother 2020 09 2. Epub 2020 Sep 2.

Department of Pediatrics, College of Medicine, The Catholic University of Korea, Seoul, Korea.

Infections with type b have been decreasing due to widespread use of conjugate vaccines thereto, and there has been an increasing trend in the relative proportion of invasive infections by non-typeable (NTHi). NTHi commonly colonizes the upper respiratory tract and causes recurrent infections of the adjacent organs. There is a rapid development of antibiotic resistance in NTHi strains, and therefore it is important to select appropriate antibiotics for treatment. We report a case of recurrent NTHi meningitis in a 5-year-old girl with a previous history of recurrent otitis media. The patient presented with fever accompanying recurrent vomiting, and β-lactamase-positive amoxicillin/clavulanate-resistant NTHi was isolated in cerebrospinal fluid culture. Antibiotic resistance testing revealed penicillin-binding protein 3 mutation, which is an important emerging mechanism of antibiotic resistance of NTHi. Cystic cochleovestibular malformation was also identified, which may be the predisposing condition for recurrent otitis media, and invasive NTHi infection. Acute symptoms resolved with antibiotic therapy (cefotaxime, 200 mg/kg per day). After surgical revision, the patient has been in good health without recurrence. In children with recurrent respiratory tract infections, or invasive NTHi infection, it is important to consider the presence of underlying diseases and infections due to antibiotic resistant pathogens, in order to select an appropriate antibiotic agent for treatment.
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http://dx.doi.org/10.3947/ic.2020.0201DOI Listing
September 2020

Seroprevalence of Neutralizing Antibodies Against Candidate Serotypes of Vaccines Among Korean Children.

Viral Immunol 2021 Mar 8;34(2):62-67. Epub 2020 Oct 8.

Department of Pediatrics, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.

Hand, foot, and mouth disease (HFMD) is a pediatric public health concern in Asia. Surveillance data on the circulating serotypes of HFMD suggest that A71 (EV-A71) and coxsackieviruses A6, A10, and A16 (CVA6, CVA10, and CVA16) are the major serotypes causing HFMD. Asian countries, including Korea, are currently developing a multivalent vaccine targeting these serotypes. However, the immunity of children against specific serotypes, indicating past infection, should also be considered while selecting candidate serotypes for vaccine development. Therefore, we aimed to identify the age-stratified serological statuses of Korean children to determine candidate serotypes for HFMD vaccine development. This study included 220 participants, categorized into four age groups, 7 months-2 years, 3-5 years, 6-10 years, and 11-15 years. A neutralization test was performed to quantitate the neutralizing antibodies (NtAbs) in the sera of the participants. Only EV-A71 and CVA6 were found suitable as candidate serotypes for vaccine development, whereas further study is needed for CVA10 and CVA16. The highest seropositivity and NtAb titer ranges were observed for CVA6 in all age groups, suggesting that the participants had been predominantly exposed to CVA6. For EV-A71, seropositivity and NtAb titer ranges steadily increased with age, suggesting that children were currently exposed to EV-A71. For CVA10, the 3-5 years group showed the highest seropositivity rate and higher NtAb titer ranges than the older age groups, indicating that the exposure to CVA10 had mainly occurred in recent years. Future studies will identify whether the exposure to CVA10 was transient or will continue. For CVA16, seropositivity and NtAb titer ranges were generally low, indicating that only a few participants had been exposed to CVA16. We identified discrepancies between the sentinel surveillance data and our findings. This study provides a new perspective for HFMD vaccine development and policy making in Asian countries.
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http://dx.doi.org/10.1089/vim.2020.0073DOI Listing
March 2021

Differences in the age distribution of influenza B virus infection according to influenza B virus lineages in the Korean population.

Postgrad Med 2021 Jan 29;133(1):82-88. Epub 2020 Sep 29.

Department of Pediatrics, College of Medicine, The Catholic University of Korea , Seoul, Republic of Korea.

Objectives: Since the 2000s, two lineages of the influenza B virus (influenza B/Victoria and influenza B/Yamagata) have been co-circulating. Information on the age distribution of patients infected by each influenza B virus lineage may be helpful for establishing differentiated influenza prevention and control strategies for each age group.

Methods: Age distributions were compared between patients infected by influenza A and B viruses and between those infected by the influenza B virus when B/Victoria and B/Yamagata lineages circulated dominantly.

Results: Between the 2014-2015 and 2018-2019 influenza seasons, 2,718 and 1,397 patients were diagnosed with influenza A and B virus infections, respectively. The median age of patients infected by the influenza B virus was lower than that of patients infected by the influenza A virus (8 vs 12 years, < 0.001). In the Yamagata season, the median ages of patients infected by influenza A and B viruses were similar (12 vs 11 years, = 0.732); however, in the Victoria season, the median age of patients infected by the influenza B virus was lower than that of patients infected by the influenza A virus (6 vs 10 years, < 0.001). In patients infected by the influenza B virus, patients aged <6 years and those aged ≥6 years were more likely to be infected during the Victoria and Yamagata seasons, respectively ( < 0.001).

Conclusion: The age distribution of patients infected by the influenza virus was different between the Yamagata and Victoria seasons. Different influenza prevention and control strategies should be considered on the basis of the predominantly circulating virus and the affected age group.
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http://dx.doi.org/10.1080/00325481.2020.1825295DOI Listing
January 2021

Immunopathogenesis of COVID-19 and early immunomodulators.

Clin Exp Pediatr 2020 Jul 18;63(7):239-250. Epub 2020 Jun 18.

The Catholic University of Korea College of Medicine, Seoul, Korea.

The novel coronavirus disease 2019 (COVID-19) is spreading globally. Although its etiologic agent is discovered as severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), there are many unsolved issues in COVID-19 and other infectious diseases. The causes of different clinical phenotypes and incubation periods among individuals, species specificity, and cytokine storm with lymphopenia as well as the mechanism of damage to organ cells are unknown. It has been suggested that in viral pneumonia, virus itself is not a direct cause of acute lung injury; rather, aberrant immune reactions of the host to the insults from viral infection are responsible. According to its epidemiological and clinical characteristics, SARS-CoV-2 may be a virus with low virulence in nature that has adapted to the human species. Current immunological concepts have limited ability to explain such unsolved issues, and a presumed immunopathogenesis of COVID-19 is presented under the proteinhomeostasis-system hypothesis. Every disease, including COVID-19, has etiological substances controlled by the host immune system according to size and biochemical properties. Patients with severe pneumonia caused by SARS-CoV-2 show more severe hypercytokinemia with corresponding lymphocytopenia than patients with mild pneumonia; thus, early immunomodulator treatment, including corticosteroids, has been considered. However, current guidelines recommend their use only for patients with advanced pneumonia or acute respiratory distress syndrome. Since the immunopathogenesis of pneumonia may be the same for all patients regardless of age or severity and the critical immune-mediated lung injury may begin in the early stage of the disease, early immunomodulator treatment, including corticosteroids and intravenous immunoglobulin, can help reduce morbidity and possibly mortality rates of older patients with underlying conditions.
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http://dx.doi.org/10.3345/cep.2020.00759DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7374000PMC
July 2020

A longitudinal hospital-based epidemiology study to assess acute otitis media incidence and nasopharyngeal carriage in Korean children up to 24 months.

Hum Vaccin Immunother 2020 12 24;16(12):3090-3097. Epub 2020 Apr 24.

Department of Pediatrics, Seoul St. Mary's Hospital, The Catholic University of Korea , Seoul, Republic of Korea.

This study was conducted to assess the nasopharyngeal (NP) carriage and acute otitis media (AOM) occurrence in Korean children who received pneumococcal conjugate vaccines (PCVs). The longitudinal study was conducted through four consecutive visits. At each visit, NP aspirates were obtained and subjects were asked to visit if AOM occurred. A total of 305 subjects were enrolled and received PCV13 (n = 182) or PCV10 (n = 123). In the PCV13 group, the NP carriage of at each visit was 2.7%, 14.8%, 18.7%, and 15.9%, respectively. Non-typeable (NTHi) was 3.3%, 2.7%, 2.7%, and 5.5%, and that of was 1.1%, 9.3%, 4.9%, and 0.5%. In the PCV10 group, the NP carriage of at each visit was 3.3%, 7.3%, 6.5%, and 4.1%, respectively. That of NTHi was 2.4%, 4.1%, 1.6%, and 0.8%, and that of was 4.1%, 0.8%, 0.8%, and 0.0%. AOM occurrence in the PCV13 group observed after the primary dose and before booster dose was 20.9%, occurrence after booster dose was 11.0%, and the incidence of two or more AOM was 11.0%. In the PCV10 group, AOM occurrence was 9.8%, 7.3%, respectively, and the incidence of two or more AOM was 2.4%. The predominant isolated were non-vaccine type (10A, 15A, and 15B). In this study, AOM occurrence was lower in the PCV10 group than in the PCV13 group. This seems to be related to ecological changes that lead to differences in NP carriage, especially and NTHi.
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http://dx.doi.org/10.1080/21645515.2020.1748978DOI Listing
December 2020

Early preemptive immunomodulators (corticosteroids) for severe pneumonia patients infected with SARS-CoV-2.

Clin Exp Pediatr 2020 Apr 8;63(4):117-118. Epub 2020 Apr 8.

The Catholic University of Korea College of Medicine, Seoul, Korea.

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http://dx.doi.org/10.3345/cep.2020.00290DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7170790PMC
April 2020

Serologic status and vaccine response against hepatitis B virus after allogeneic hematopoietic cell transplantation in pediatric patients.

Asian Pac J Allergy Immunol 2020 Mar 29. Epub 2020 Mar 29.

Department of Pediatrics, Daejeon St. Mary's Hospital, College of Medicine, The Catholic University of Korea.

Background: Although vaccination against hepatitis B virus (HBV) is recommended for hematopoietic cell transplantation (HCT) recipients, previous studies evaluating serologic status and immunologic response to HBV vaccination in pediatric allogeneic HCT recipients are not enough.

Objective: This study aimed to evaluate serologic status against HBV and immunologic responses to HBV vaccination in children and adolescents receiving allogeneic HCTs.

Methods: Medical records of the enrolled 61 pediatric patients < 19 years of age who received their first allogeneic HCTs were retrospectively reviewed.

Results: Twenty-two (36.1%) of the enrolled patients were positive for hepatitis B surface antibody (HBsAb) after HCT. Chronic graft-versus-host disease was significantly associated with negative HBsAb status after HCT (p = 0.01). With one dose of HBV vaccination after HCT, 40.5% of the vaccinated patients became positive for HBsAb. No clinical factor was associated with the positive conversion of HBsAb after vaccination.

Conclusions: Considering the unsatisfactory seropositive rate and vaccine response against HBV and the lack of significant clinical and laboratory factors predicting serostatus in HCT recipients, universal three doses of HBV vaccination should be necessary after allogeneic HCT.
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http://dx.doi.org/10.12932/AP-221219-0724DOI Listing
March 2020

Review of Measles in Korea: Quarantine and Elimination.

Authors:
Jin Han Kang

Infect Chemother 2020 Mar;52(1):113-122

Department of Pediatrics, College of Medicine, The Catholic University of Korea, Seoul, Korea.

Strong policies were established to maintain vaccination rate at ≥95% to expedite the eradication and elimination of measles outbreaks; nationwide survey of measles immunity to determine the susceptibility and the mandatory submission of second measles vaccination records when entering primary school. The measles control policies were also implemented to help achieve the goal of eliminating measles after the catch-up vaccination and they can be summarized as strategies for classifying measles patients based on their clinical symptoms while anticipating that weaker symptoms than those in typical cases would be seen; improving the operation of laboratories to world-class level for diagnosis of measles and identification of epidemiological circumstances for strengthen the detection of patients suspected of having measles; and immediate response through a rapid reporting system. With these efforts, Korea became the country to make the declaration of measles elimination by complying with all standards presented by the World Health Organization in 2006, re-verified in 2014. However, sporadic outbreaks of measles have repeatedly occurred even after the declaration of measles elimination. This indicates the need for continued control of imported cases and possible re-outbreaks. Also, it will be necessary to find and implement measures to continuously maintain the policy.
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http://dx.doi.org/10.3947/ic.2020.52.1.113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7113451PMC
March 2020

Deep Neck Inflammation: Probable Kawasaki Disease in Korean Children.

Clin Exp Otorhinolaryngol 2020 Feb 11;13(1):77-82. Epub 2019 Oct 11.

Department of Pediatrics, College of Medicine, The Catholic University of Korea, Seoul, Korea.

Objectives: Deep neck infections (DNIs) can cause life-threatening complications, and prompt diagnosis and management are necessary. Kawasaki disease (KD) may be accompanied by deep neck inflammation; making it difficult to distinguish from DNIs. This study was performed to evaluate clinical features and outcomes of children with parapharyngeal and retropharyngeal inflammation.

Methods: Medical records of the children diagnosed with parapharyngeal and retropharyngeal cellulitis or abscess using cervical computed tomography (CT) between 2013 and 2017 were retrospectively reviewed.

Results: A total of 47 children were diagnosed with parapharyngeal and retropharyngeal inflammation. Eleven (23.4%) of them were eventually diagnosed with KD, and 36 (76.6%) were diagnosed with DNIs. There were no significantly different clinical and laboratory characteristics on admission between children diagnosed with KD and DNIs; however, significantly more children with KD were febrile for ≥3 days after admission compared to those with DNIs (P=0.009). Deep neck abscesses on CT were observed in 16 children with DNIs (44.4%) and in no child with KD (P=0.009). Among the 36 children with DNIs, 30 (83.3%) were cured with antibiotic therapy only.

Conclusion: A quarter of children presenting with deep neck inflammation were diagnosed with KD. KD should be considered in children showing deep neck inflammation unresponsive to empirical antibiotic therapy after 3 days, especially in those presenting with deep neck cellulitis rather than deep neck abscess.
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http://dx.doi.org/10.21053/ceo.2019.00948DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7010501PMC
February 2020

Serological Changes against Hepatitis B Surface Antigen in Children and Adolescents Receiving Chemotherapy for Acute Leukemia.

Mediterr J Hematol Infect Dis 2019 1;11(1):e2019052. Epub 2019 Sep 1.

Department of Pediatrics, College of Medicine, The Catholic University of Korea, Seoul, Korea.

Background: Vaccination for hepatitis B virus (HBV) after chemotherapy among pediatric patients with acute Leukemia is still a debated issue. We investigated HBV immunity before and after chemotherapy and assessed immune response to re-vaccination after chemotherapy.

Methods: We retrospectively analyzed data of children and adolescents aged <19 years requested for vaccination after chemotherapy for acute leukemia to evaluate hepatitis B surface antibody (HBsAb) status before and after chemotherapy and to identify factors related to HBsAb positivity after chemotherapy.

Results: Of 89 enrolled patients, 61 (68.5%) with acute leukemia were HBsAb positive before chemotherapy. Of these 61 patients, 48 (78.7%) seroconverted to HBsAb negative status after chemotherapy; there were 76 (85.4%) HBsAb negative patients after chemotherapy. HBsAb positive patients when compared to HBsAb negative patients after chemotherapy had a significantly higher HBsAb positive rate (100.0% vs. 63.2%, =0.008) before chemotherapy. Following HBsAb testing after one dose of the HBV vaccination, 33 (43.4%) of the 76 HBsAb negative patients seroconverted to an HBsAb positive status. HBsAb positive patients after a single dose of HBV vaccination had a significantly higher HBsAb positive rate at the time of diagnosis compared to HBsAb negative patients (84.8% vs. 48.8%, =0.001).

Conclusions: Based on these results, HBV re-vaccination after chemotherapy is recommended for all children and adolescents with acute leukemia. In addition, further investigation is required to improve the immunogenicity of HBV re-vaccination.
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http://dx.doi.org/10.4084/MJHID.2019.052DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6736336PMC
September 2019

A clinico-epidemiological multicenter study of herpes zoster in immunocompetent and immunocompromised hospitalized children.

Clin Exp Vaccine Res 2019 Jul 31;8(2):116-123. Epub 2019 Jul 31.

Department of Pediatrics, Seoul St. Mary's Hospital, Seoul, Korea.

Purpose: There are limited population-based data regarding herpes zoster in children. Thus we conducted a multi-institutional epidemiological analysis of herpes zoster in children and comparative analysis according to their immune status.

Materials And Methods: The study included 126 children under the age of 18 years who were hospitalized for herpes zoster at 8 hospitals in South Korea, between July 2009 and June 2015. The subjects were divided into 2 groups according to their immune status, and medical records were reviewed.

Results: There were 61 cases (48.4%) in the immunocompetent group and 65 cases (51.6%) in the immunocompromised group. Median age was older in immunocompromised group (11.4 vs. 8.6) (p<0.001). The mean duration of hospitalization was longer in immunocompromised group (11.0 vs. 6.6) (p<0.001). Patients were treated with oral or intravenous antiviral agents. A total of 12 in immunocompetent group were cured only by oral acyclovir. No treatment failure was found in both groups. Six immunocompromised patients had postherpetic neuralgia and 1 case was in immunocompetent group. In immunocompetent children, herpes zoster was likely caused by early varicella infection. There was no increase in progression of severity in both groups due to appropriate treatment.

Conclusion: Early initiation of therapy is necessary for those in immunocompromised conditions. And inactivated herpes zoster vaccination may be considered in immunocompromised adolescents in the future.
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http://dx.doi.org/10.7774/cevr.2019.8.2.116DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6689498PMC
July 2019

Reply letter: trends in varicella and herpes zoster epidemiology before and after the implementation of universal one-dose varicella vaccination over one decade in South Korea, 2003-2015.

Hum Vaccin Immunother 2019 1;15(11):2562-2563. Epub 2019 Aug 1.

Vaccine Bio Research Institute, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.

In the letter, Lai SW suggested that the cost-benefit of two-dose varicella vaccines should be considered since universal one-dose vaccination effectively reduced varicella incidence in Taiwan. However, the vaccination impact was different between South Korea and Taiwan. In South Korea, only a moderate reduction in varicella incidence was observed after implementing universal one-dose vaccination. Such difference possibly reflects the relatively high background varicella incidence in South Korea. As substantial variability in varicella epidemiology exists across countries, an optimal vaccination strategy may differ in each country. Despite the effectiveness of one-dose vaccine being moderate, primary vaccine failure and rapidly waning immunity are major concerns. Therefore, two-dose vaccination would be a reasonable choice for effectively preventing virus transmission in South Korea.
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http://dx.doi.org/10.1080/21645515.2019.1643678DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6930042PMC
January 2020

Seroprevalence of Hepatitis A Virus in Pediatric Patients with Hematologic Malignancies after Chemotherapy and Hematopoietic Cell Transplantation.

Infect Chemother 2019 Jun;51(2):183-187

Department of Pediatrics, College of Medicine, The Catholic University of Korea, Seoul, Korea.

This retrospective study was performed to determine the seroprevalence of hepatitis A virus (HAV) in children and adolescents with hematologic malignancies after the completion of chemotherapy and hematopoietic cell transplantation (HCT). Of 97 enrolled patients, 60 (61.9%) were seropositive for HAV. The seroprevalences in patients undergoing chemotherapy and HCT were 60.3% (41/68) and 65.5% (19/29), respectively ( = 0.628). No significant factors associated with seropositivity for HAV after chemotherapy and HCT were identified. Anti-HAV tests and HAV re-vaccinations can be considered in children and adolescents with underlying hematologic malignancies after chemotherapy and HCT based on the anti-HAV results.
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http://dx.doi.org/10.3947/ic.2019.51.2.183DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6609742PMC
June 2019

Early Corticosteroid Therapy for Pneumonia Irrespective of Used Antibiotics in Children.

J Clin Med 2019 May 22;8(5). Epub 2019 May 22.

Departments of Pediatrics, College of Medicine, The Catholic University of Korea, Seoul 06591, Korea.

Antibiotics' effect on (MP) infection still remains controversial. A prospective study of 257 children with MP pneumonia during a recent epidemic (2015-2016) was conducted. All MP pneumonia patients were treated with corticosteroids within 24-36 h after admission. Initially, oral prednisolone (1 mg/kg) or intravenous methylprednisolone (IVMP; 1-2 mg/kg) was administered for mild pneumonia patients, and IVMP (5-10 mg/kg/day) for severe pneumonia patients. If patients showed a persistent fever for 36-48 h or disease progression, additive IVMP (5 mg/kg or 10 mg/kg) was given. Thirty-three percent of patients received only a broad-spectrum antibiotic without a macrolide. The mean age and the male-to-female ratio was 5.6 ± 3.1 years and 1:1, respectively. Seventy-four percent of patients showed immediate defervescence within 24 h, and 96% of patients showed defervescence within 72 h with improvements in clinical symptoms. Three percent of patients (8/257) who received additive IVMP also showed clinical improvement within 48 h without adverse reactions. There were no clinical or laboratory differences between patients treated with a macrolide ( = 172) and without ( = 85). Early corticosteroid therapy might reduce disease morbidity and prevent disease progression in MP pneumonia patients without side effects, and antibiotics may have limited effects on MP infection.
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http://dx.doi.org/10.3390/jcm8050726DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6572103PMC
May 2019

Trends in varicella and herpes zoster epidemiology before and after the implementation of universal one-dose varicella vaccination over one decade in South Korea, 2003-2015.

Hum Vaccin Immunother 2019 7;15(11):2554-2560. Epub 2019 May 7.

Vaccine Bio Research Institute, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.

: In South Korea, the one-dose varicella vaccine was included in the National Immunization Program for children aged 12-15 months in 2005, and the vaccine coverage reached >95%. The impact of varicella vaccination on varicella and herpes zoster (HZ) was investigated, accounting for demographic changes over time.: We calculated the crude and age-sex standardized incidence rates (IRs) and age-specific IRs of varicella and HZ from 2003 to 2015, using the National Health Information Database including approximately 50 million Koreans. The annual incidence rate ratios (IRRs) were calculated using a negative binomial regression analysis, adjusting for age and sex.: The crude varicella IR steadily declined by 67%, from 5.70/1000 to 1.87/1000 person years (IRR per year: 0.91; 95% CI 0.89-0.93), but the adjusted IRs showed a significant decline only during 2010-2015 (adjusted IRR per year: 0.90; 95% CI 0.88-0.93). The greatest decline was found in children ≤4 years of age, whereas the IR increased until 2011 and then declined afterward in children aged 5-9 years, who represented the highest incidence age group in 2013-2015. The crude HZ IR increased from 2.67/1000 to 9.80/1000 person years (IRR per year: 1.12; 95% CI 1.10-1.15), and the adjusted IR also followed the same trend. A similar increasing trend was observed before and after universal vaccination.: One-dose varicella vaccination was moderately effective in preventing varicella, but this strategy was insufficient to interrupt varicella transmission in children. Furthermore, the HZ incidence dramatically increased over this decade. The current vaccination strategy against varicella-zoster disease should be reconsidered.
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http://dx.doi.org/10.1080/21645515.2019.1603985DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6930048PMC
May 2020

The Measles Strikes Back.

J Korean Med Sci 2019 Feb 12;34(6):e59. Epub 2019 Feb 12.

Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.

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http://dx.doi.org/10.3346/jkms.2019.34.e59DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6374549PMC
February 2019

Enzyme-linked immunosorbent assay for detecting anti-pertussis toxin antibody in mouse.

Clin Exp Vaccine Res 2019 Jan 31;8(1):64-69. Epub 2019 Jan 31.

The Vaccine Bio Research Institute, College of Medicine, The Catholic University of Korea, Seoul, Korea.

Purpose: Although the DTaP and Tdap vaccines used to prevent pertussis have been used for a long time, there is no standard method for measuring pertussis antigens. Therefore, this preliminary study was conducted to develop an enzyme-linked immunosorbent assay method using an animal model for measuring antibodies against pertussis toxin, the most important pertussis pathogenic antigen, in the sera of vaccinated mice.

Materials And Methods: Tohama phase I was cultured for 24-30 hours, and then pertussis toxin was purified from the culture medium by chromatography. Purified pertussis toxin was diluted in phosphate-buffered saline-coating buffer, and 100 µL of diluted pertussis toxin was added to each well and reacted at room temperature for 4 hours. Positive serum was diluted to 1/1,250-1/80,000 and negative serum was diluted to 1/50 to determine the coating concentration with the optimal signal/noise ratio. Optimal test conditions were confirmed from the dilution factors of the secondary antibody and streptavidin horseradish peroxidase (SA-HRP).

Results: Optimal conditions were as follows: 4 µg/mL for coating antigen; 1/40,000 for secondary antibody; and 1/1,000 for the SA-HRP dilution factor. Comparison of the sera obtained from mice treated with a developing vaccine and commercial vaccine with National Institute for Biological Standard and Control standard serum under the established conditions showed the following results: 1,300.62, 534.94, and 34.85, respectively.

Conclusion: The method developed in this study is suitable for measuring anti-pertussis toxin antibodies and may be applicable for clinical sample analysis or indirect diagnosis of pertussis.
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http://dx.doi.org/10.7774/cevr.2019.8.1.64DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6369130PMC
January 2019

Development and implementation of standardized method for detecting immunogenicity of acellular pertussis vaccines in Korea.

Clin Exp Vaccine Res 2019 Jan 31;8(1):35-42. Epub 2019 Jan 31.

Vaccine Bio Research Institute, The Catholic University of Korea, Seoul, Korea.

Purpose: There is no standard method for confirming the immunogenicity of acellular pertussis vaccines. We tried to develop a local standard method for evaluating the immunogenicity of the three-component of acellular pertussis vaccines which was developed by a Korean local company.

Materials And Methods: The developed pertussis antigens (pertussis toxin, filamentous hemagglutinin, pertactin) were evaluated by in-house enzyme-linked immunosorbent assay (ELISA) using 189 negative sera, 25 positive sera, and 73 paired sera (pre- and post-Tdap [tetanus, diphtheria, and acellular pertussis] vaccinated sera). ELISA units were calculated by the reference line method, compared with World Health Organization reference sera, and the cut-off value was calculated using negative sera.

Results: When compared to National Institute for Biological Standards and Control control antigen (NIBSC) control antigens, the developed pertussis toxin (PT) and filamentous haemagglutinin (FHA) antigens were 203.48 and 61.60 IU/µg, respectively. Each in-house ELISA was established by validating the coefficients of variation % (PT, 11.53%; FHA, 8.60%; pertactin [PRN], 9.86%) obtained from the results of inter- and intra-assay variation. Also, the cut-off values of PT, FHA, and PRN were 11.65, 38.95, and 5.66 EU/mL, respectively. The distributions of antibody levels in paired showed that 93.15% (68/73) in anti-PT IgG, 97.26% (72/73) in anti-FHA IgG, and 100% in anti-PRN IgG were higher than a 100% increase after vaccination. Additionally, the values of 89.04% (65/73) in anti-PT IgG, 97.26% (72/73) in anti-FHA IgG, and 100% in anti-PRN IgG were below each cut-off point.

Conclusion: We established an in-house ELISA method using self-developed antigens, and these immunoassays have provided a way to standardize measuring the immunogenicity of newly developed vaccines, through single- and dual-serology.
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http://dx.doi.org/10.7774/cevr.2019.8.1.35DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6369126PMC
January 2019

Comparison of the immunogenicity and safety of 3 inactivated hepatitis A vaccines in Korean children aged 12 to 18 months: An open-label, randomized, prospective, multicenter study.

Medicine (Baltimore) 2019 Feb;98(6):e14364

Department of Pediatrics, College of Medicine, The Catholic University of Korea, Seoul.

Several approved inactivated hepatitis A (HA) vaccines are available in Korea. These have been shown to be immunogenic and safe in European children; however, their immunogenicity and safety have not been investigated among Korean children. We aimed to compare the immunogenicity and safety of the most commonly used HA vaccines in ethnic Korean children aged 12 to 18 months.In this open-label, randomized, prospective, multicenter study, 108 children were enrolled and randomized to receive a pediatric form of Avaxim, Epaxal, or Havrix. The 2nd dose was administered after an interval of 6 months. Anti-HA virus (HAV) immunoglobulin (Ig) G was measured to assess geometric mean concentrations (GMCs) and seropositvity rates (≥20 mIU/mL anti-HAV IgG). To assess safety, local solicited adverse events (AEs), systemic solicited AEs, unsolicited AEs, and serious AEs (SAEs) were graded.Among the 108 participants enrolled, 37, 34, and 37 received Avaxim, Epaxal, and Havrix, respectively. After administration of 2 doses, the seropositivity rates in the Avaxim, Epaxal, and Havrix groups were all 100% (95% confidence intervals [CIs]: 99.0-100, 98.9-100, and 99.0-100, respectively; P < .001). The anti-HAV GMCs in the Avaxim, Epaxal, and Havrix groups were 5868.4 (95% CI: 4237.2-8126.6), 1962.1 (95% CI: 1298.0-2965.9), and 2232.9 mIU/mL (95% CI: 1428.4-3490.4), respectively, after administration of 2 doses (P < .001). There were no significant differences in the proportions of participants reporting local solicited AEs, systemic solicited AEs, unsolicited AEs, and SAEs among the 3 vaccine groups after the 1st and 2nd doses. All local solicited and unsolicited AEs were grade 1 or 2. Grade 3 systemic solicited AE occurred in 5.4% and 2.9% of the participants in the Havrix group after the 1st and 2nd doses, respectively. SAEs after the 1st and 2nd doses were reported in 2 participants and 1 participant, respectively, but none was assessed as being related to vaccination.The results indicate that these vaccines were safe and immunogenic in ethnic Korean children. The results have contributed to the establishing of an HA vaccination policy in Korea and will be informative to countries that plan to initiate vaccination programs against HAV.
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http://dx.doi.org/10.1097/MD.0000000000014364DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6380807PMC
February 2019

A Phase III Study to Evaluate the Immunogenicity and Safety of GC1107 (Adult Tetanus Diphtheria Vaccine) in Healthy Adults.

J Korean Med Sci 2019 Jan 16;34(4):e31. Epub 2019 Jan 16.

Department of Pediatrics, Seoul St. Mary's Hosptial, College of Medicine, The Catholic University of Korea, Seoul, Korea.

Background: This study was conducted to assess the immunogenicity and safety of GC1107 (adult tetanus diphtheria [Td] vaccine). The primary goal was to evaluate the non-inferiority of the immunogenicity of GC1107 compared to the control vaccine. Additionally, the safety profiles of GC1107 and the control vaccine were compared.

Methods: The subjects were adults ≥ 18 years old who were not injected with Td or adult tetanus-diphtheria-pertussis (TdaP) vaccine within the recent 5 years. A total of 253 subjects were enrolled and randomized to either the GC1107 group or the control group. For immunogenicity assessment, blood samples were collected at baseline and 28 days after vaccination and antibody titer of diphtheria and tetanus were assessed.

Results: The seroprotection rates of diphtheria and tetanus were 89.76% and 91.34%, respectively, in the GC1107 group, and 87.80% and 86.99% in the control group. The geometric mean titer (GMT) of the anti-diphtheria antibody increased after vaccination in both groups, showing no significant difference between the groups ( = 0.139). The anti-tetanus GMTs after vaccination also showed comparable increases in both groups, and showed no significant difference ( = 0.860). In the safety evaluation, solicited local adverse reactions occurred in 81.2% of the subjects in the GC1107 group and in 86.4% of the subjects in the control group. Solicited systemic adverse events occurred in 33.2% of the subjects in the GC1107 group and in 47.2% of the subjects in the control group, which did not reach statistical significance.

Conclusion: This phase III study demonstrated non-inferiority in immunogenicity and comparable safety of GC1107 compared with the control Td vaccine.

Trial Registration: ClinicalTrials.gov Identifier: NCT02361866.
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http://dx.doi.org/10.3346/jkms.2019.34.e31DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6345633PMC
January 2019

Respiratory Viral Infections in Children and Adolescents with Hematological Malignancies.

Mediterr J Hematol Infect Dis 2019 1;11(1):e2019006. Epub 2019 Jan 1.

Department of Pediatrics, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea.

Background: Despite the introduction of a polymerase chain reaction (PCR) test for the diagnosis of respiratory viral infection (RVI), guidance on the application of this test and the management of RVI in immunocompromised children is lacking. This study evaluated the clinical characteristics of RVI and established strategies for the PCR test in children and adolescents with hematological malignancies.

Methods: This study included children and adolescents with underlying hematological malignancies and respiratory symptoms, in whom a multiplex PCR test was performed. Patients in whom RVI was identified and not identified were categorized into Groups I and II, respectively. Group I was sub-divided into patients with upper and lower respiratory infections. The medical records of the enrolled patients were retrospectively reviewed.

Results: A total of 93 respiratory illnesses were included. Group I included 46 (49.5%) cases of RVI, including 31 (67.4%) upper and 15 (32.6%) lower respiratory infections. Rhinovirus (37.0%) was the most common viral pathogen. Significantly more patients in Group I had community-acquired respiratory illnesses (=0.003) and complained of rhinorrhea (<0.001) and sputum (=0.008) than those in Group II. In Group I, significantly more patients with lower respiratory infections had uncontrolled underlying malignancies (=0.038) and received re-induction or palliative chemotherapy (=0.006) than those with upper respiratory infections.

Conclusions: A multiplex PCR test should be considered for RVI diagnosis in immunocompromised children and adolescents with respiratory symptoms, especially in those with rhinorrhea or sputum prominent over a cough. The early application of the PCR test in patients with uncontrolled underlying malignancies may improve outcomes.
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http://dx.doi.org/10.4084/MJHID.2019.006DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6328038PMC
January 2019

Enterococcal bacteremia in febrile neutropenic children and adolescents with underlying malignancies, and clinical impact of vancomycin resistance.

Infection 2019 Jun 19;47(3):417-424. Epub 2018 Dec 19.

Department of Pediatrics, College of Medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul, 06591, Republic of Korea.

Purpose: Enterococci are a common cause of bacteremia in immunocompromised patients. Although the increase of vancomycin-resistant enterococci (VRE) makes appropriate antibiotic therapy difficult, clinical characteristics of enterococcal bacteremia and the impact of VRE infection on outcomes have rarely been reported in immunocompromised children.

Methods: We enrolled children and adolescents (< 19 years of age) with underlying malignancies who were diagnosed with enterococcal bacteremia during febrile neutropenia between 2010 and 2017. Medical records of the enrolled children were retrospectively reviewed to evaluate the clinical characteristics of enterococcal bacteremia and impact of VRE infection on outcomes.

Results: Thirty-six episodes of enterococcal bacteremia were identified in 30 patients. VRE infection was identified in 11 episodes (30.6%); the 7- and 30-day mortalities were 27.8% and 44.4%, respectively. Acute lymphoblastic leukemia (50.0%) and acute myeloid leukemia (30.6%) were the most common underlying disorders. Three (8.3%) of the patients were in complete remission, and palliative and reinduction chemotherapies were administered in 47.2% and 36.1% of episodes, respectively. Empirical antibiotic therapy was appropriate in 64.0% of patients with vancomycin-susceptible enterococcal infection and in none of the VRE-infected patients (p = 0.001). However, the 30-day mortality was not significantly different between the two patient groups (44.0% vs. 45.5%, p = 1.000).

Conclusions: Most episodes of enterococcal bacteremia occurred in advanced stages of underlying malignancies, and still showed high mortality. The prognosis seemed to be related to the underlying disease condition rather than vancomycin resistance of the isolated enterococci, although the number of enrolled patients was small.
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http://dx.doi.org/10.1007/s15010-018-1260-zDOI Listing
June 2019

Risk factors for latent tuberculosis infection in children in South Korea.

Postgrad Med 2018 Sep 22;130(7):637-643. Epub 2018 Aug 22.

a Department of Pediatrics, College of Medicine , The Catholic University of Korea , Seoul , Republic of Korea.

Objectives: In South Korea, latent tuberculosis infection (LTBI) screening is a critical strategy associated with efforts to reduce the incidence of tuberculosis (TB). Currently, only children with a known history of TB contact are considered as pediatric high-risk groups for LTBI, and consequently, LTBI screening is only provided to these children. However, to reduce the incidence of TB, the high-risk groups that undergo LTBI screening should be expanded. This study aimed to assess the risk factors for LTBI among children living in South Korea with no known history of TB contact for the identification of additional high-risk groups. We investigated the risk factors for LTBI among US visa applicant children, who undergo LTBI screening regardless of their TB contact history.

Methods: We obtained data on demographic characteristics, medical history, Bacillus Calmette-Guerin (BCG) vaccination history, and results of LTBI screening for children aged 2-14 years. A tuberculin skin test was used for the diagnosis of LTBI, and an induration of 10 mm or greater was used to define a positive test. Adjusted odds ratios and 95% confidence intervals were calculated to determine the association between clinical and demographic variables and LTBI.

Results: Of the 1,664 study participants, 91 (5.5%) had LTBI. The binary logistic regression analysis showed that children born in high TB burden foreign countries had the highest odds of LTBI when considering all the risk factors investigated. Increasing age, absence of BCG vaccination, and a previous diagnosis of asthma were also significant risk factors for LTBI.

Conclusion: These results indicate that children born in high TB burden foreign countries should be considered a high-risk group for LTBI in South Korea; the inclusion of these children in LTBI screening should be considered.
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http://dx.doi.org/10.1080/00325481.2018.1510709DOI Listing
September 2018

Genetic structures of invasive Streptococcus pneumoniae isolates from Korean children obtained between 1995 and 2013.

BMC Infect Dis 2018 06 8;18(1):268. Epub 2018 Jun 8.

Department of Pediatrics, University of Ulsan College of Medicine, Seoul, South Korea.

Background: Understanding the population genetics of pneumococci will allow detection of changes in the prevalence of circulating genotypes and evidence for capsular switching. We aimed to analyze the genetic structure of invasive pneumococcal isolates obtained from children before and after the use of pneumococcal conjugate vaccines (PCVs) in Korea.

Methods: A total of 285 invasive pneumococcal isolates were analyzed using serotyping, multilocus sequence typing, and antimicrobial susceptibility testing. We classified the isolation year to pre-PCV7 (1995-2003; n = 70), post-PCV7 (2004-2010; n = 142), and post-PCV13 (2011-2013; n = 73) periods.

Results: Of the 10 clonal complexes (CCs), antibiotic-resistant international clones, CC320 (31.6%), CC81 (14.7%), and CC166 (6.7%) were the main complexes. Serotype 19A was the main serotype of CC320 throughout the periods. Serotypes of CC81 mainly comprised of 23F (53.3%) in pre-PCV7 period and replaced by non-vaccine types (NVTs; 6C [10%], 13 [30%], 15A [40%], and 15B/C [20%]) in post-PCV13 period. The main serotype responsible for CC166 also changed from 9 V (80%) in pre-PCV7 to NVT 11A (50%) in post-PCV13 periods. Non-susceptibility to penicillin (42.3%) was the highest in CC320, increasing from 0 to 76%.

Conclusion: The genetic structures of invasive pneumococcal isolates in Korean children have changed concomitantly with serotype after the implementation of PCVs.
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http://dx.doi.org/10.1186/s12879-018-3177-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5994121PMC
June 2018