• Neonatal Medicine
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• v.16 no.1
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• pp.94-98
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• 2009

Listeria monocytogenes (L. monocytogenes) is a foodborne anaerobic gram-positive rod and the third most common pathogen for neonatal meningitis. Although the mortality and morbidity of L. monocytogenes infections are high, thus causing serious problems in Western populations, neonatal listeriosis is relatively rare in Eastern countries, including Korea. Possible routes for intrauterine infection or vertical transmission of L. monocytogenes include infected placentas and the reproductive tract. Intrauterine infections may cause chorioamnionitis, preterm labor, spontaneous abortion, stillbirth, or neonatal infection. A high index of suspicion and early empirical antibiotic treatment are critical to achieve a favorable prognosis for neonatal listeriosis. We managed a case of L. monocytogenes sepsis and pneumonia in a premature neonate born at 26 weeks of gestational age from an asymptomatic mother with culture-proven placental infection. The neonate was successively treated with ampicillin and gentamicin.

• Parasites, Hosts and Diseases
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• v.37 no.3
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• pp.149-156
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• 1999

Pneumocystis carinii is pulmonary pathogen of immunocompromised humans or other mammals. Its infection results from activation of organism involves in latent infection or form new infection through the air. Almost all children are known to be infected within 2 to 4 years of birth, though prenatal transplacental transmission has not yet been demonstrated. In this study we observed experimental P.carinii infection in neonatal rats, thus investigating the possibility of transplacental vertical transmission by Diff-Quik staining of the lung impression smears and in-sity hybridization for lung sections. The postive rate of P.carinii infection in immunosuppressed maternal rats was 100%, but that in normal maternal rats was 0%. Cystic forms of P.carinii were observed in three of six 1-week old neonatal rats born of heavily infected mothers, but none of them was positive by in-situ hybridization. Five weeks after birth, cystic forms were detected in four neonatal rats. In the lobes of the lungs, no predilection site of P.carinii was recognized. Counts of cystic forms on smears and the reactivity of in-situ hbridization in the lungs of neonatal rats 0 were signficantly lower than in maternal rats. The present findings suggest that P.carinii is rarely transmitted through the placenta and proliferates less successfully in the lungs of neonatal rats than in mothers.

• Clinical and Experimental Pediatrics
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• v.53 no.12
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• pp.989-993
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• 2010

Although numerous clinical observational studies have been conducted over a period of over 30 years, the clinical significance of $Ureaplasma$ infection is still under debate. The $Ureaplasma$ speices. is a commensal in the female genital tract and considered to have of low virulence; however, $Ureaplasma$ colonization has been associated with infertility, stillbirth, preterm delivery, histologic chorioamnionitis, and neonatal morbidities, including congenital pneumonia, meningitis, bronchopulmonary dysplasia, and perinatal death. Recently, $Ureaplasma$ was subdivided into 2 separate species and 14 serovars. $Ureaplasma$ $parvum$ is known as biovar 1 and contains serovars 1, 3, 6, and 14, and $Ureaplasma$ $urealyticum$ (biovar 2) contains the remaining serovars (2, 4, 5, and 7-13). The existence of differences in pathogenicities of these 14 serovars and 2 biovars is controversial. Although macrolides are the only antimicrobial agents currently available for use in neonatal ureaplasmal infections, in the current clinical field, it is difficult to make decisions regarding which antibiotics should be used. Future investigations involving large, multicenter, randomized, controlled studies are needed before proper recommendations can be made for clinical practice.

• Pediatric Infection and Vaccine
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• v.21 no.3
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• pp.219-224
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• 2014

Invasive infection of the Streptococcus bovis group in a neonate is rare. In cases reported to date, the pathogen of neonatal S. bovis infections is usually Streptococcus gallolyticus subsp. pasteurianus (S. bovis biotype II/2). Streptococcus lutetiensis (S. bovis biotype II/1) was identified using 16S rRNA and tuf gene sequence analysis of the isolates from blood and cerebrospinal fluid (CSF) of a fever-presenting 28-day-old male. Blood culture analysis was performed using automatic equipment (VITEK 2) and identified Streptococcus infantarius supsp. infantarius, yet we were unable to get accurate results from the CSF culture. The fever subsided on the second day of hospitalization, and the patient was discharged without neurologic complication after 14 days of antibiotic therapy. In this case, we were able to accurately identify the pathogen using molecular genetic methods. To our knowledge, this is the first case of late onset neonatal bacteremia and meningitis caused by S. lutetiensis.

• Bulletin of Food Technology
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• v.18 no.3
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• pp.45-61
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• 2005

The first cases of neonatal meningitis believed to have been caused by Enterobacter sakazakii were reported in 1961. Prompted by several subsequent outbreaks of E. sakazakii infections in neonates and an increasing number of neonates in intensive care units being fed rehydrated powdered infant formula, considered to be a source of the pathogen, public health authorities and researchers are exploring ways to eliminate the bacterium or control its growth in dry infant formula, processing environments and formula preparation areas in hospitals. Reviewed here are advances in taxonomy and classification of E. sakazakii, methods of detecting, isolating and typing the bacterium, antibiotic resistance, clinical etilogy and pathogenicity. Outbreaks of E. sakazakii infections in neonates and adults are summarized. Reports on the presence of E. sakazakii in clinical settings, the environment and foods and food processing facilities are reviewed.

• Pediatric Infection and Vaccine
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• v.6 no.2
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• pp.194-202
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• 1999

Background : Group B ${\beta}$-hemolytic Streptococcus(GBS) has been the major pathogen of neonatal sepsis in western country. In contrast, GBS has played little role in neonatal sepsis in Korea. But recently, neonatal GBS infections are encountered more frequently. It is important to characterize the clinical and epidemiological features of GBS infection in Korean children. Methods: We reviewed retrospectively the medical records of twenty-seven infants and children with GBS infection experienced at the Seoul National University Children's Hospital during 14 year-period from June, 1985 to June, 1999. Fourteen strains isolated from blood and cerebrospinal fluid were serotyped. Minimum inhibitory concentrations of 10 strains were determined by agar dilution method for penicillin, ampicillin, ampicillin with sulbactam, cefarolin, cefuroxime, and cefuiaxone. Results: The numbers of cases with GBS infection increased in 1990s. Among twenty seven cases, twenty-five cases were under three months of age and both of two cases with underlying disease occurred at three years of age. All neonatal infections were late-onset type and meningitis predominated. Serotypes were III(6 strain), Ib(4), Ia(l) and V(2). All of the strain were susceptible to all of the antibiotics tested. Conclusion: GBS infections in infants were increasingly recognized. GBS should be considered as an etiological agent of neonatal sepsis or meningitis in Korea. Maternal screening and prophylactic antibiotic therapy may be considered.

• Clinical and Experimental Pediatrics
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• v.56 no.8
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• pp.332-337
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• 2013

Purpose: To identify the frequency of bacterial isolates in early-onset neonatal sepsis (EONS) and their antimicrobial resistance pattern. Methods: A retrospective study of EONS was conducted at the Beni Suef University Hospital from September 2008 to September 2012. A case of EONS was defined as an infant who had clinical signs of infection or who was born to a mother with risk factors for infection, and in whom blood culture obtained within 72 hours of life grew a bacterial pathogen. Results: Of 673 neonates screened, there were 138 positive blood cultures (20.5%) (confirmed EONS). Of the recovered isolates, 86.2% were gram-negative pathogens. Klebsiella pneumoniae (42.8%), Enterobacter cloacae (22.5%), and Escherichia coli (13.8%) were the commonest isolated organisms. The most common gram-positive microorganism was Staphylococcus aureus accounting for only 12 isolates (8.7%). All Klebsiella isolates and 93% of Enterobacter isolates were resistant to ampicillin. Gram-negative pathogens had the maximum overall sensitivity to imipenem, cefepime, and ciprofloxacin; whereas, gram-positive isolates were most susceptible to vancomycin, imipenem, and piperacillin. Conclusion: K. pneumoniae was the predominant causative bacteria of EONS followed by E. cloacae and E. coli. There was a high resistance to ampicillin. Imipenem had the maximum overall activity against the causative bacteria. Continuous surveillance is needed to monitor the changing epidemiology of pathogens and antibiotic sensitivity.

• Korean Journal of Veterinary Research
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• v.61 no.2
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• pp.12.1-12.9
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• 2021

The mosquito-borne pathogen Zika virus may result in neurological disorders such as Guillain-Barré syndrome and microcephaly. The virus is classified as a member of the Flaviviridae family and its wide spread in multiple continents is a significant threat to public health. So, there is a need to develop animal models to examine the pathogenesis of the disease and to develop vaccines. To examine the clinical profile during Zika virus infection, we infected neonatal and adult wild-type mice (C57BL/6 and Balb/c) and compared the clinical signs of African-lineage strain (MR766) and Asian-lineage strain (PRVABC59, MEX2-81) of Zika virus. Consistent with previous reports, eight-week-old female Balb/c mice infected with these viral strains showed no changes in body weight, survival rate, and neurologic signs, but demonstrated increases in the weights of spleens and hearts. However, one-day-old neonates showed significantly lower survival rate and body weight with the African-lineage strain than the Asian-lineage strain. These results confirmed the pathogenic differences between Zika virus strains. We also evaluated the clinical responses in neonatal and adult mice of different strains. Our findings suggest that these are useful mouse models for characterization of Zika virus for vaccine development.

• Clinical and Experimental Pediatrics
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• v.62 no.1
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• pp.36-41
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• 2019

Purpose: In this study, we investigated the clinical features and prognostic factors of early-onset sepsis (EOS) in neonatal intensive care unit (NICU) patients. Methods: A retrospective analysis was conducted on medical records from January 2010 to June 2017 (7.5 years) of a university hospital NICU. Results: There were 45 cases of EOS (1.2%) in 3,862 infants. The most common pathogen responsible for EOS was group B Streptococcus (GBS), implicated in 10 cases (22.2%), followed by Escherichia coli, implicated in 9 cases (20%). The frequency of gram-positive sepsis was higher in term than in preterm infants, whereas the rate of gram-negative infection was higher in preterm than in term infants (P<0.05). The overall mortality was 37.8% (17 of 45), and 47% of deaths occurred within the first 3 days of infection. There were significant differences in terms of gestational age (26.8 weeks vs. 35.1 weeks) and birth weight (957 g vs. 2,520 g) between the death and survival groups. After adjustments based on the difference in gestational age and birth weight between the 2 groups, gram-negative pathogens (odds ratio [OR], 42; 95% confidence interval [CI], 1.4-1,281.8) and some clinical findings, such as neutropenia (OR, 46; 95% CI, 1.3-1,628.7) and decreased activity (OR, 34; 95% CI, 1.8-633.4), were found to be associated with fatality. Conclusion: The common pathogens found to be responsible for EOS in NICU patients are GBS and E. coli. Gram-negative bacterial infections, decreased activity in the early phase of infection, and neutropenia were associated with poor outcomes.

• Food Science and Biotechnology
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• v.14 no.6
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• pp.875-877
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• 2005

Presence of Enterobacter sakazakii, occasional pathogen of powdered infant formula causing rare, but life-threatening diseases such as neonatal meningitis, bacteremia, necrotizing enterocolitis, and necrotizing meningoencephalitis after ingestion was examined in 45 powdered infant formula products manufactured in Korea using chromogenic Druggan-Forsythe-Iversen (DFI) medium, and isolates were identified with API 20E. Ent. sakazakii was isolated from three products. Ent. sakazakii isolates were genotyped by RAPD-PCR using two random primers, and their banding patterns were compared.