• Tuberculosis and Respiratory Diseases
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• v.78 no.3
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• pp.196-202
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• 2015

Background: Viridans streptococci (VS) are a large group of streptococcal bacteria that are causative agents of community-acquired respiratory tract infection. However, data regarding their clinical characteristics are limited. The purpose of the present study was to investigate the clinical and radiologic features of community-acquired pneumonia (CAP) with or without parapneumonic effusion caused by VS. Methods: Of 455 consecutive CAP patients with or without parapneumonic effusion, VS were isolated from the blood or pleural fluid in 27 (VS group, 5.9%) patients. Streptococcus pneumoniae was identified as a single etiologic agent in 70 (control group) patients. We compared various clinical parameters between the VS group and the control group. Results: In univariate analysis, the VS group was characterized by more frequent complicated parapneumonic effusion or empyema and bed-ridden status, lower incidences of productive cough, elevated procalcitonin (>0.5 ng/mL), lower age-adjusted Charlson comorbidity index score, and more frequent ground glass opacity (GGO) or consolidation on computed tomography (CT) scans. Multivariate analysis demonstrated that complicated parapneumonic effusion or empyema, productive cough, bed-ridden status, and GGO or consolidation on CT scans were independent predictors of community-acquired respiratory tract infection caused by VS. Conclusion: CAP caused by VS commonly presents as complicated parapneumonic effusion or empyema. It is characterized by less frequent productive cough, more frequent bed-ridden status, and less common CT pulmonary parenchymal lesions. However, its treatment outcome and clinical course are similar to those of pneumococcal pneumonia.

• Pediatric Infection and Vaccine
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• v.15 no.2
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• pp.206-211
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• 2008

Streptococcus pneumoniae is a common cause of acute otitis media, sinusitis, pneumonia, and the invasive bacterial infections in children. Rarely, S. pneumoniae is an uncommon cause of hemolytic-uremic syndrome (HUS). We report a 33 month-old girl who presented with pneumonia, and subsequently developed HUS. Her pulmonary infection was complicated by necrotizing pneumonia and acute respiratory distress syndrome. Cultures from blood and pleural fluid grew S. pneumoniae, serotype 19A. She was treated with antibiotics, dialysis and mechanical ventilatory support. She was discharged with normal renal function after 2 months of management. She remained healthy without renal complications at the 5 year follow-up visit.

• Pediatric Infection and Vaccine
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• v.24 no.3
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• pp.160-167
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• 2017

Purpose: Because children with asplenia have an increased risk of fulminant infection associated with a high fatality, chemoprophylaxis, and vaccinations against encapsulated bacteria are recommended. However, there have been few reports of the burden of severe bacterial infection and the current status of chemoprophylaxis and immunization among children with asplenia in Korea. Methods: We conducted a retrospective study including children with asplenia who were treated at our institute between January 1997 and December 2016. Results: From a total of 213 children with asplenia, 114 (53.5%) had congenital asplenia and 58 (27.2%) had functional asplenia. The remaining 41 (19.3%) had acquired asplenia with the median age at splenectomy being 12.2 years (range, 5.0 to 16.9 years); the most common cause of splenectomy was hereditary spherocytosis (39.0%). The chemoprophylaxis rate was 16.4%. The immunization rates were 44.1% for pneumococcus, 53.0% for Haemophilus influenzae type B, and 10.7% for meningococcus. The incidence of invasive bacterial infection among children with asplenia was 0.28/100 person-year; a total of six episodes (2.8%) were observed in five patients with congenital asplenia and one patient with functional asplenia. The median age for these infections was 15 months (range, 4 to 68 months). Five of the six episodes were bacteremia, and the other was meningitis. The most common pathogen was Streptococcus pneumoniae (n=3), followed by H. influenzae (n=1). Three of the six patients (50.0%) died, all of whom had pneumococcal bacteremia. None of the six had chemoprophylaxis or proper vaccinations. Conclusions: Although there is an increased risk of a severe infection proper vaccinations and chemoprophylaxis are still lacking. Physicians should be encouraged to implement appropriate chemoprophylaxis and immunizations for patients with asplenia.

• Clinical and Experimental Pediatrics
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• v.48 no.1
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• pp.40-47
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• 2005

Purpose : S. pneumoniae is one of major pathogens of community-acquired respiratory infections. The rate of antibiotic resistance to this organism has increased, and resistance to multiple antimicrobial agents in a single strain of S. pneumoniae may compromise the efficacy of empiric antimicrobial treatment commonly used for respiratory infections. We did this study to find out the penicillin resistant distributions and oral antibiotics susceptibility patterns against S. pneumoniae, isolated from pediatric patients with community-acquired respiratory infections in Korea. Methods : One hundred fifty six pneumococcal isolates obtained from pediatric patients with community-acquired respiratory infections such as acute otitis media(AOM), sinusitis and pneumonia between May 2000 to June 2003. And MICs of penicillin and oral antibiotics(amoxicillin, amoxicillin-clavulanate, cefaclor) were performed by broth microdilution methods according to the NCCLS(2003a). Results : Seventy eight percent of the isolates were resistant to penicillin. The isolates, collected from AOM patients showed the highest penicillin resistance(92.7%). The resistant rates of amoxicillin (16.7%) and amoxicillin-clavulanate(9.6%), based on susceptibility breakpoints established by the NCCLS, were markedly lower than these of penicillin. But, the resistant rate of cefaclor was very high, above 95%. Conclusion : We concluded that pneumococci isolated from study cases may be one of the world's highest penicillin resistant rates. But, amoxicillin and amoxicillin-clavulanate can be used as a first-line antibiotics. Finally, we hope that a continuous surveillance study to monitor resistant patterns of pneumococcal respiratory infections will be needed for the standard guidelines of empiric antibiotic treatment.

• Proceedings of the Microbiological Society of Korea Conference
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• 2008.05a
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• pp.23-25
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• 2008

Serum complement proteins comprise an important system that is responsible for several innate and adaptive immune defence mechanisms. There were three well described pathways known to lead to the generation of a C3 convertase, which catalyses the proteolysis of complement component C3, and leads to the formation of C3 opsonins (C3b, iC3b and C3d) that fix to bacteria. A pivotal step in the complement pathway is the assembly of a C3 convertase, which digests the C3 complement component to form microbial-binding C3 fragments recognized by leukocytes. The spleen clears microorganisms from the blood. Individuals lacking this organ are more susceptible to Streptococcus pneumoniae. Innate resistance to S. pneumoniae has previously been shown to involve complement components C3 and C4, however this resistance has only a partial requirement for mediators of these three pathways, such as immunoglobulin, factor B and mannose-binding lectin. Therefore it was likely that spleen and complement system provide resistance against blood-borne S. pneumoniae infection through unknown mechanism. To better understand the mechanisms involved, we studied Specific intracellular adhesion molecule-grabbing nonintegrin (SIGN)-R1. SIGN-R1, is a C-type lectin that is expressed at high levels by spleen marginal-zone macrophages and lymph-node macrophages. SIGN-R1 has previously been shown to be the main receptor for bacterial dextrans, as well as for the capsular pneumococcal polysaccharide (CPS) of S. pneumoniae. We examined the specific role of this receptor in the activation of complement. Using a monoclonal antibody that selectively downregulates SIGN-R1 expression in vivo, we show that in response to S. pneumoniae or CPS, SIGN-R1 mediates the immediate proteolysis of C3 and fixation of C3 opsonins to S. pneumoniae or to marginal-zone macrophages that had taken up CPS. These data indicate that SIGN-R1 is largely responsible for the rapid C3 convertase formation induced by S. pneumoniae in the spleen of mice. Also, we found that SIGN-R1 directly binds C1q and that C3 fixation by SIGN-R1 requires C1q and C4 but not factor B or immunoglobulin. Traditionally C3 convertase can be formed by the classical C1q- and immunoglobulin-dependent pathway, the alternative factor-B-dependent pathway and the soluble mannose-binding lectin pathway. Furthermore Conditional SIGN-R1 knockout mice developed deficits in C3 catabolism when given S. pneumoniae or its capsular polysaccharide intravenously. There were marked reductions in proteolysis of serum C3, deposition of C3 on organisms within SIGN-$R1^+$ spleen macrophages, and formation of C3 ligands. The transmembrane lectin SIGN-R1 therefore contributes to innate resistance by an unusual C3 activation pathway. We propose that in the SIGN-R1 mediated complement activation pathway, after binding to polysaccharide, SIGN-R1 captures C1q. SIGN-R1 can then, in association with several other complement proteins including C4, lead to the formation of a C3 convertase and fixation of C3. Therefore, this new pathway for C3 fixation by SIGN-R1, which is unusual as it is a classical C1q-dependent pathway that does not require immuno globulin, contributes to innate immune resistance to certain encapsulated microorganisms.

• Pediatric Infection and Vaccine
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• v.19 no.1
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• pp.19-27
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• 2012

Purpose : As the number of children who attend child care centers has increased, concerns has increased about the effect of child day care on childhood illness. This study was conducted to examine the relationship between experience in child care and common infectious diseases in children under 5 years of age. Methods : Data were collected by surveying 1,000 respondents with children under age 5 through online interviews using a structured questionnaire. The contents of the survey were composed of demographic characteristics, child care facilities usage, experience in infectious diseases, and immunization status Results : Among the 1,000 children <5 years of age, 78.5% attended a child care facility. Rates of common communicable illnesses were higher in children in child care than for children reared exclusively at home. The predominant communicable diseases which the respondents' children experienced, in order of decreasing frequency, were gastroenteritis (47.1%), otitis media (41.8%) and pneumonia (19.1%). The immunization rate of vaccines that are not included the national immunization program (NIP) (Haemophilus influenzae type b vaccine - 76.6%, hepatitis A vaccine - 63.3%, pneumococcal vaccine - 59.4%, rotavirus vaccine - 43.1%) was lower than that of the NIP vaccines (90.4%) Conclusion : Children in child care experience more bouts of common infectious disease, so nationwide policies to prevent or to control the spread of infectious agents in a child-care should be available and appropriate immunization should be emphasized as the most effective method for the control of infectious disease for children.

• Clinical and Experimental Pediatrics
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• v.46 no.9
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• pp.846-853
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• 2003

Purpose : Pneumoccocus is one of the most important causes of invasive infection through the childhood period and the prevelance of antibiotics resistance of pneumococcus is increasing worldwide. A 7-valent conjugate vaccine has been developed. It is important to know the prevalence of each serotype of pneumococci in the countries where the vaccine is used to estimate the coverage rate by the vaccine. Methods : One hundred and twenty seven strains of clinical isolates and 72 strains from healthy carriers recovered from Korean children during the period from 1997 to 2002 were subjected to determination of serotype by Quellung reaction and penicillin susceptibility with oxacillin disc diffusion test. Results : Forty-three per cent of clinical isolates were obtained from children under two years of age. Thirty strains(24%) were isolated from normally sterile body fluids. The frequent serotypes were 19F, 19A, 23F, 6A, 6B and 9V. Fifty-six per cent of the clinical isolates were represented in the current 7-valent protein conjugate pneumococccal vaccine, and 84% when the cross-reactive serotypes were included. Frequent serotypes of strains isolated from one to five year-old healthy children were 19F, 14, 11A, 23F, 18C, and 19A. Seventy-one per cent of the carrier strains were included in the 7-valent vaccine. Ninety-three per cent of the clinical isolates and 86% of carrier strains were not susceptible to penicilline. Conclusion : Fifty-six to 84% of pneumococci recovered from Korean children are covered by the current 7-valent protein conjugate pneumococcal vaccine and the prevalence of penicillin resistance was very high.

• Pediatric Infection and Vaccine
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• v.17 no.2
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• pp.91-100
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• 2010

Purpose : Recurrent otitis media (ROM) is usually defined as ${\geq}$3 distinct and well-documented episodes within 6 months or ${\geq}$4 episodes within 12 months. ROM is sufficiently important to warrant consideration of chemoprophylaxis, tympanostomy tube placement. There also is evidence that children with ROM are at risk for both hearing loss and speech delay. However, studies of ROM have been notably insufficient. In addition, even though environmental, racial, and sociocultural differences can affect risk factors, few studies have been conducted with regard to recurrent otitis media in Korea. Methods : This study was conducted from July 2009 to January 2010 with infants and children who were younger than 60 months old, who visited the out-patient clinics at Han-Il General Hospital and Kyunghee University Hospital. Data were collected by interview using a pre-formed sheet. Among a total of 892 infants and children, 457 were excluded, and the remaining 435 were allocated to 104 with ROM and 331 as a control group. Results : Attendance at daycare centers (P<0.001, OR=2.85), allergic rhinitis (P=0.026, OR=2.32), past history of bronchiolitis (P=0.003, OR=2.33), and low socioeconomic status (P=0.005, OR=2.00) were found to have a close significant correlation with ROM. Risk factors such as sex, having a sibling, breast-feeding, use of pacifiers, atopy, pneumococcal vaccination, influenza vaccination, smoking of parents, and indoor smoking are not relevant. Conclusion : Attendance at daycare centers, allergic rhinitis, past history of bronchiolitis, and low socioeconomic status have been identified as risk factors for ROM.

• Pediatric Infection and Vaccine
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• v.13 no.2
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• pp.130-136
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• 2006

Purpose : The purpose of this study is to confirm the epidemiologic change of the causative organisms of neonatal and pediatric bacterial meningitis in Korea. And we tried to evaluate the risk factors correlated with prognosis which was available on the day of admission. Methods : Retrospectively, we reviewed the medical records of 57 patients admitted for bacterial meningitis at six hospitals affiliated with Catholic Medical Center for 6 years(Jan. 2000~Dec. 2005). Results : 22 cases(38.6%) of them were neonates under 28 days and 35 cases were infants and children ; 16 cases(28.1%), under 1 year ; 6 cases(10.5%), under 5 years ; 13 cases (22.8%), under 15 years. In neonates, 16 cases(72.7%) were caused by group B streptococcus (GBS). In infants and children, S. pneumoniae(25.7%), H. influenzae type b(Hib)(22.8%) and N. meningitidis(22.8%) were common cause of bacterial meningitis in order. In the informations available on the day of admission, weight deficit for age under 3 percentile, increased CRP level and decreased glucose level of CSF were related to poor prognosis(P<0.05). Conclusion : GBS became a leading cause of neonatal bacterial meningitis. Though, pneumoccocal, Hib and meningococcal meningitis were confirmed as major causes of bacterial meningitis. The routine immunization of pneumococcal and Hib vaccines will be considered, and it is necessary to introduce meningococcal vaccines to our country in the future.

• Pediatric Infection and Vaccine
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• v.13 no.2
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• pp.163-173
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• 2006

Purpose : To reduce the number of injections necessary to vaccinate young infants, various combined vaccines have been developed. The $Comvax^{TM}$ manufactured by Merck & Co. is a combination of Hepatitis B and PRP-OMP conjugate Haemophilus influenzae Type b vaccine. The purpose of this study is to evaluate the immunogenicity and safety of $Comvax^{TM}$ in Korean infants. Methods : The infants who were vaccinated at 0 months of age with Hepatitis B vaccine, were recruited for this study after parental informed consent was obtained. The subjects were vaccinated with $Comvax^{TM}$ at 2 and 4 months of age. At each visit, infants were also immunized with DTaP, inactivated poliovirus vaccine, and pneumococcal vaccine when indicated. The serum anti-PRP and anti-HBs were measured at 2 months after the 1st dose(4 months age), and the 2nd dose(6 months age) by the ELISA and chemiluminescent microparticle immunoassay method, respectively. The local and systemic adverse reactions of vaccination were monitored for 3 consecutive days after each immunization. Results : Among sixty-five healthy infants(35 male infants) enrolled in this study; fifty eight(32 male infants) completed the scheduled immunizations. The geometric mean titers (GMTs) of anti-PRP at 2 months after the 1st dose and the 2nd dose were 1.96 ${\mu}g/mL$ (95% CI; 1.38~2.78) and 10.02 ${\mu}g/mL$ (95% CI; 7.04~14.26), respectively. Anti-PRP ${\geq}1.0$ ${\mu}g/mL$, was obtained in 63.2%(95% CI; 53.75~72.65) after 1 dose, and 96.6%(95% CI; 93.05~100) after 2 doses. The GMTs of anti-HBs were 38.32 mIU/mL(95% CI; 22.42~65.51), and 101.17 mIU/mL(95% CI; 65.94~155.25) at 2 month after the 1st dose and 2nd dose of $Comvax^{TM}$, respectively. Anti-HBs ${\geq}10$ mIU/mL was observed in 73.7%(95% CI; 65.07~82.33) after 1 dose and 94.8%(95% CI; 90.45~99.15) after 2 doses. Most of the adverse reactions after vaccination were mild. Irritability, the most common systemic reaction, was observed in 24.8%, followed by drowsiness(19.2%), poor feeding(19.2%) and fever(7.2%). Among the local reactions tenderness was observed in 25.6%, redness(${\geq}5$ mm) in 19.2% and swelling(${\geq}5$ mm) in 4.8%. Conclusion : The $Comvax^{TM}$ vaccine was highly immunogenic for PRP and safe in Korean infants. Although the hepatitis B vaccine component was administered at 0, 2, 4 months, this study showed good immunogenicity against HBsAg.