Eun Hee Chung

The Causative Organisms of Bacterial Meningitis in Korean Children in 1996-2005

Bacterial meningitis remains a serious cause of morbidity and mortality in childhood, despite the availability of effective vaccines against Haemophilus influenzae type b (Hib) or Streptococcus pneumoniae. The purpose of this study was to analyze data on bacterial meningitis cases in Korea from 1996 through 2005. The information of all hospitalized bacteria-proven meningitis cases was obtained from 17 university hospitals nationwide. A total of 402 cases were identified. Of these, 125 (29.9%) cases were neonates. Streptococcus agalactiae was the most common bacteria responsible for 99 (24.6%) of all cases regardless of age, followed by S. pneumoniae for 91 (22.6%) and H. influenzae for 67 (16.7%) patients. The common etiology beyond the neonatal period was S. pneumoniae for 91 (33.0%) followed by H. influenzae for 63 (22.8%) patients. The overall case fatality rate was 9.4%, which was similar with that in 1986-1995. In conclusion, S. agalactiae, S. pneumoniae and H. influenzae were important etiologic agents of bacterial meningitis in children in the last 10 yrs. It is required to establish the preventive strategy of the three bacteria. The nationwide epidemiologic study should be continued to evaluate immunization strategy and efficacy.

Comparison of polymerase chain reaction and the indirect particle agglutination antibody test for the diagnosis of Mycoplasma pneumoniae pneumonia in children during two outbreaks.

Background: Diagnosis of Mycoplasma pneumoniae pneumonia is challenging because of the lack of standardized rapid tests. Many serologic tests and polymerase chain reaction (PCR) based methods are used with different diagnostic criteria. Methods: This retrospective study was conducted to compare the diagnostic values of the indirect particle agglutination test and nested PCR of nasopharyngeal aspirates for the diagnosis of M. pneumoniae pneumonia in children. These assays were evaluated in 234 hospitalized children with community-acquired lower respiratory tract infections during 2 outbreaks of M. pneumoniae pneumonia in 2000 and 2003. Results: The cumulative PCR positive rate was 26.7% in patients with maximum antibody titers of ≤1:320 and 78.2% in those with titers of ≥1:640. Based on these data, a positive PCR, a 4-fold increase in antibody titer, or a single titer ≥1:640 were considered to indicate acute M. pneumoniae infection. Overall, 152 children were diagnosed to have M. pneumoniae pneumonia; 27 (18%) by serology only, 26 (17%) by PCR only, and 99 (65%) by both methods. Children who were diagnosed by PCR only were significantly younger (P = 0.003) and were more often immunocompromised (P = 0.019) than those that were PCR negative. Duration of cough before PCR diagnosis was shorter in cases diagnosed by PCR only than those that were PCR negative (P = 0.045). Conclusions: In conclusion, during the 2 outbreaks of M. pneumoniae infection, we found that the PCR test may be useful for the rapid diagnosis of M. pneumoniae pneumonia, particularly in young children and in immunocompromised patients and in early stage disease.

Prevalence of primary immunodeficiency in Korea

This study represents the first epidemiological study based on the national registry of primary immunodeficiencies (PID) in Korea. Patient data were collected from 23 major hospitals. A total of 152 patients with PID (under 19 yr of age), who were observed from 2001 to 2005, have been entered in this registry. The period prevalence of PID in Korea in 2005 is 11.25 per million children. The following frequencies were found: antibody deficiencies, 53.3% (n = 81), phagocytic disorders, 28.9% (n = 44); combined immunodeficiencies, 13.2% (n = 20); and T cell deficiencies, 4.6% (n = 7). Congenital agammaglobulinemia (n = 21) and selective IgA deficiency (n = 21) were the most frequently reported antibody deficiency. Other reported deficiencies were common variable immunodeficiencies (n = 16), X-linked agammaglobulinemia (n = 15), IgG subclass deficiency (n = 4). Phagocytic disorder was mostly chronic granulomatous disease. A small number of patients with Wiskott-Aldrich syndrome, hyper-IgE syndrome, and severe combined immunodeficiency were also registered. Overall, the most common first manifestation was pneumonia. This study provides data that permit a more accurate estimation PID patients in Korea.

Immunogenicity and Safety of Two Different Haemophilus influenzae Type b Conjugate Vaccines in Korean Infants

The incidence of invasive diseases, including meningitis caused by Haemophilus influenzae type b (Hib) was markedly decreased after routine immunization of Hib vaccine through diverse schedules in many countries. The purpose of this study was to evaluate the immunogenicity and safety of Hib conjugate vaccines in Korean children before the implementation of a national immunization program against Hib in Korea. A multicenter controlled trial was performed on two different Hib vaccines in Korean children. A total of 319 infants were enrolled: 199 infants were immunized with the Hib polysaccharide conjugated to the tetanus toxoid (PRP-T) and 120 infants with the Hib polysaccharide conjugated to the outer-membrane protein of Neisseria meningitides (PRP-OMP). Immunogenicity was evaluated by enzyme-linked immunosorbent assay (ELISA) and serum bactericidal assay. Both vaccines showed good immunologic responses after primary immunization. After 2 doses of PRP-T or PRP-OMP, 78.9% and 91.7% of infants achieved an antibody level of ≥1.0 µg/mL, respectively. Both vaccines were safe and well-tolerated. No serious adverse events were observed. Thus, Hib conjugate vaccines appear to be safe and show good immunogenicity in Korean infants. These results will be important reference data for the implementation of Hib vaccine in the national immunization program of Korea.

Immunogenicity and safety of a combined diphtheria, tetanus, acellular pertussis, and inactivated poliovirus vaccine (DTaP–IPV) compared to separate administration of standalone DTaP and IPV vaccines: A randomized, controlled study in infants in the Republic of Korea☆

This randomized trial enrolled 442 infants in the Republic of Korea to assess the immunogenicity and safety of a combined diphtheria, tetanus, acellular pertussis, and inactivated poliovirus vaccine (DTaP-IPV; Tetraxim™) for primary vaccination at 2, 4 and 6 months of age compared with DTaP and IPV vaccines given separately. Immunogenicity was high in both groups; seroprotection and seroconversion rates of the combined vaccine (Group A) were non-inferior to the control vaccines (Group B). All subjects were seroprotected against poliovirus types 1, 2 and 3 (≥ 81/dil) and anti-diphtheria (≥ 0.01 IU/mL); 99.0% were seroprotected against tetanus (≥ 0.1 IU/mL). At least 93.6% had anti-diphtheria antibody titers ≥ 0.1 IU/mL. Anti-pertussis toxoid (PT) and anti-filamentous haemagglutinin (FHA) seroconversion (≥ 4-fold increase in antibody titer) rates were 96.6% and 94.4% for Group A, 92.2% and 78.4% for Group B. Most solicited reactions occurred within 4 days of vaccination, resolved within 3 days and were mild. Severe solicited reactions occurred after ≤ 0.5% of doses in Group A and ≤ 0.9% in Group B. No withdrawals occurred because of adverse events. The DTaP-IPV combined vaccine given at 2, 4, and 6 months of age was well tolerated; immunogenicity was similar to the control vaccines.

Current status and clinical presentations of invasive neonatal Group B streptococcal infections in Korea

Background:  Group B streptococcus (GBS) is the most common cause of invasive neonatal infections in developed countries. The incidence of early‐onset GBS disease in Korea is known to be much lower than that in other developed countries; however neonatal GBS disease has been frequently reported in recent years in Korea. This retrospective study sought to determine the current status and clinical presentation of neonatal GBS disease in Korea.

Varicella and Varicella Vaccination in South Korea

ABSTRACT With continuing occurrence of varicella despite increasing vaccine coverage for the past 20 years, a case-based study, a case-control study, and an immunogenicity and safety study were conducted to address the impact of varicella vaccination in South Korea. Varicella patients under the age of 16 years were enrolled for the case-based study. For the case-control study, varicella patients between 12 months and 15 years of age were enrolled with one control matched for each patient. For the immunogenicity and safety study, otherwise healthy children from 12 to 24 months old were immunized with Suduvax (Green Cross, South Korea). Fluorescent antibody to membrane antigen (FAMA) varicella-zoster virus (VZV) antibody was measured before and 6 weeks after immunization. In the case-based study, the median age of the patients was 4 years. Among 152 patients between 1 and 15 years of age, 139 children received varicella vaccine and all had breakthrough infections. Clinical courses were not ameliorated in vaccinated patients, but more vaccinated patients received outpatient rather than inpatient care. In the case-control study, the adjusted overall effectiveness of varicella vaccination was 54%. In the immunogenicity and safety study, the seroconversion rate and geometric mean titer for FAMA antibody were 76.67% and 5.31. Even with increasing varicella vaccine uptake, we illustrate no upward age shift in the peak incidence, a high proportion of breakthrough disease, almost no amelioration in disease presentation by vaccination, and insufficient immunogenicity of domestic varicella vaccine. There is need to improve the varicella vaccine used in South Korea.

Seasonal Patterns of Asthma in Children and Adolescents Presenting at Emergency Departments in Korea

Purpose Seasonal variations in asthma-related hospitalizations and emergency department visits have long been recognized. This study aimed to investigate the seasonal patterns of asthma in children and adolescents who presented at emergency departments in Korea. Methods We analyzed the National Emergency Department Information System records from 117 emergency departments in Korea that comprised all of the patients with asthma who were aged 3-18 years and who presented at the emergency departments from 2007 to 2012. The children and adolescents were divided into 3 groups based on their ages, namely, 3-6 years, 7-12 years, and 13-18 years. The data were tabulated, and graphs were created to show the seasonal trends in the monthly numbers of emergency department visits as a consequence of asthma. Results A total of 41,128 subjects were identified, and the male-to-female ratio was 1:0.5. General ward admissions comprised 42.6% (n=17,524 patients) of the emergency department visits, and intensive care unit admissions comprised 0.8% (n=335 patients) of the emergency department visits. The monthly numbers of emergency department visits for asthma varied according to the season, with high peaks during fall, which was from September to November, and low levels in summer, which was from June to August. Conclusions Important differences in the seasonal patterns of emergency department visits for asthma were evident in children and adolescents. Identifying seasonal trends in asthma-related emergency department visits may help determine the causes and reduce the likelihood of asthma exacerbation.

Clinical characteristics of children and adolescents with croup and epiglottitis who visited 146 Emergency Departments in Korea

Purpose Croup is a common pediatric respiratory illness with symptoms of varying severity. Moreover, epiglottitis is a rare disease that can rapidly progress to life-threatening airway obstruction. Although the clinical course and treatments differ between croup and epiglottitis, they are difficult to differentiate on presentation. We aimed to compare the clinical characteristics of croup and epiglottitis in Emergency Department patients. Methods The 2012 National Emergency Department Information System database of 146 Korean Emergency Departments was used to investigate patients aged ≤18 years presenting with croup or epiglottitis. Results We analyzed 19,374 croup patients and 236 epiglottitis patients. The male:female sex ratios were 1.9:1 and 2.3:1 and mean ages were 2.2±2.0 and 5.6±5.8 years, respectively. The peak incidence of croup was observed in July and that of epiglottitis was observed in May. The hospitalization rate was lower in croup than in epiglottitis patients, and the proportion of patients treated in the intensive care unit was lower among croup patients. The 3 most common chief complaints in both croup and epiglottitis patients were cough, fever, and dyspnea. Epiglottitis patients experienced dyspnea, sore throat, and vomiting more often than croup patients (P<0.05). Conclusion Both groups had similar sex ratios, arrival times, 3 most common chief complaints, and 5 most common comorbidities. Epiglottitis patients had a lower incidence rate, higher mean age of onset, and higher hospitalization rate and experienced dyspnea, sore throat, and vomiting more often than croup patients. Our results may help in the differential diagnosis of croup and epiglottitis.

A nationwide study of children and adolescents with pneumonia who visited Emergency Department in South Korea in 2012.

Purpose Acute respiratory infection, particularly pneumonia, is the most common cause of hospitalization and death among children in developing nations. This study aimed to investigate the characteristics of children and adolescents with pneumonia who visited Emergency Department (ED) in South Korea in 2012. Methods We analyzed National Emergency Department Information System (NEDIS) records from 146 EDs in South Korea for all pediatric patients aged ≤18 years who were diagnosed with pneumonia between January and December 2012. Results Among 38,415 subjects, the male-to-female ratio was 1:0.8. Patients aged <12 months comprised 18.0% of the study population; those aged 1 to 3 years, 54.4%; those aged 4 to 6 years, 16.8%; those aged 7 to 12 years, 7.4%; and those aged 13 to 18 years, 3.4%. Presentation rates were highest in April, followed by January, March, and May. The hospital admission rate was 43.5%, of which 2.6% were in intensive care units. The mortality rate was 0.02%. Based on the International Classification of Diseases, 10th Revision, diagnostic codes, the types of pneumonia according to cause were viral pneumonia (29.0%), bacterial pneumonia (5.3%), Mycoplasmal pneumonia (4.5%), aspiration pneumonia (1.3%), and pneumonia of unknown origin (59.3%). Conclusion Despite the limited data due to the ED data from the NEDIS lacking laboratory results and treatment information, this study reflects well the outbreak patterns among children and adolescents with pneumonia. Our results provide a basis for future studies regarding ED treatment for children and adolescents with pneumonia.