• Journal of Microbiology and Biotechnology
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• v.33 no.6
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• pp.736-744
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• 2023

The introduction of the toxT-139F allele triggers the expression of TCP (toxin co-regulated pilus) and CT (cholera toxin) under simple laboratory culture conditions in most Vibrio cholerae strains. Such V. cholerae strains, especially strains that have been used in OCVs (oral cholera vaccines), can induce antibody responses against TCP in animal models. However, CT produced in these V. cholerae strains is secreted into the culture medium. In this study, V. cholerae strains that can express intracellular CTB under the control of the toxT-139F allele have been constructed for potential application in OCVs. First, we constructed a recombinant plasmid directly linking the ctxAB promoter to ctxB without ctxA and confirmed CTB expression from the plasmid in V. cholerae containing the toxT-139F allele. We constructed another recombinant plasmid to express NtrCTB, from which 14 internal amino acids-from the 7^th to the 20^th amino acid-of the leader peptide of CTB have been omitted, and we found that NtrCTB remained in the cells. Based on those results, we constructed V. cholerae strains in which chromosomal ctxAB is replaced by ntrctxB or ntrctxB-dimer. Both NtrCTB and NtrCTB-dimer remained in the bacterial cells, and 60% of the NtrCTB-dimer in the bacterial cells was maintained in a soluble form. To develop improved OCVs, these strains could be tested to see whether they induce immune responses against CTB in animal models.

• Pediatric Infection and Vaccine
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• v.30 no.3
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• pp.165-172
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• 2023

Pyogenic liver abscess is a rare condition in healthy children in developed countries, but it can have severe consequences if diagnosis and treatment are delayed. Staphylococcus aureus is the most commonly identified cause of pyogenic liver abscess worldwide, while Klebsiella pneumoniae is the predominant causative agent in Korea. However, cases of pyogenic liver abscess caused by anaerobic bacteria have also been rarely reported. A 14-year-old boy presented to the emergency room with fever and pain in the upper right abdomen. He exhibited tenderness in the right upper quadrant, elevated white blood cell count, anemia, and elevated liver enzyme levels. Abdominal computed tomography with contrast revealed pyogenic liver abscess. The patient underwent percutaneous catheter drainage for two weeks and received a 4-week course of antibiotic therapy. Prevotella intermedia, an anaerobic bacterium commonly found in the oral flora, was isolated from the drained pus. However, no evidence was found suggesting that the infection originated from a dental source. This case highlights the importance of considering the possibility of pyogenic liver abscess even in otherwise healthy children.

• Pediatric Infection and Vaccine
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• v.5 no.2
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• pp.215-220
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• 1998

Purpose : Asymptomatic infections with positive throat culture for group A beta-hemolytic streptococci(GABHS) and high antistreptolysin O(ASO) concentration may lead to sequelae such as rheumatic fever or acute poststreptococcal glomerulonephritis. Children with asymptomatic infections were treated with oral penicillin V to evaluate the effectiveness of penicillin treatment on the asymptomatic infections. Methods : Throat culture and ASO concentration analysis were performed against healthy elementary school children. Thirty-six children with positive throat culture for GABHS and ASO concentrations of 400 IU/mL or more were divided into two groups. Twenty-two children were treated with oral penicillin V for 10 days, and the others were not treated. Eradication rate of GABHS and the change of ASO concentration between the two groups were compared after one month later. Results : Eradication rates of GABHS between treated and untreated children were 91%(20/22) and 50%(7/14) respectively(P<0.05). Children showing elevation of ASO levels more than 100IU/mL were 22%(4/18) in the treated group and 30%(3/10) in the untreated group, while children showing a decrease of more than 200IU/mL in the ASO level were 44%(8/18) and 40%(4/10) respectively. Conclusion : We confirmed the validity of penicillin treatment, because when we treated the asymptomatic children with penicillin V, the GABHS was eradicated effectively. But there was no significant difference of decrease in the ASO levels between the two groups due to long half-life of ASO or poor compliance. Treatment failure was 22% in terms of elevated ASO levels after penicillin treatment.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.9 no.2
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• pp.153-161
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• 2006

Purpose: This study was designed to investigate rotavirus infection by comparing the clinical characteristics in neonates and infants. Methods: We enrolled 104 neonates and 250 infants wiht gastroenteritis and a rotazyme test positive reaction at the Soonchunhyang University Bucheon Hospital from February 2001 to January 2003. Results: The seasonal peaks of infection in infants occurred from February to June. However, in neonates, it occurred from October to December due to nursery outbreaks. Diarrhea, vomiting, fever and convulsions were significant symptoms in infants; however, metabolic acidosis with dehydration, jaundice, irritability, apnea, bloody stool, gastric residual, grunting, poor oral intake, lethargy as well as fever and diarrhea were more common in the neonates. Upper respiratory infection, pneumonia and bronchitis were present in the infants; however, necrotizing enterocolitis was more commonly observed in the in neonates. Among the patients with rotaviral infection, formula feeding was more popular than breast milk feeding in both the neonates and infants; however, this finding was not statistically significant. Conclusion: Rotavirus can be a significant pathogen in neonates as well as infants. Neonates suffering from fever, poor oral intake, lethargy and apnea should be investigated for rotaviral infection. A new vaccine, rotaviral specific immunoglobulin and treatment guidelines are needed for eradicating rotavirus infection. Further studies on isolation, infection pathway, immune response and treatment of rotavirus are needed.

• Pediatric Infection and Vaccine
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• v.22 no.3
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• pp.201-205
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• 2015

Acute maxillary sinusitis is a common disorder affecting children. Untreated acute sinusitis can develop into chronic sinusitis, and complications, such as orbital cellulitis or abscess, can occur. Maxillary sinusitis of odontogenic origin is not a well-recognized condition and is frequently missed in children. As an odontogenic source of sinusitis, the dentigerous cyst is one of the most prevalent types of odontogenic cysts, and it is associated with the crown of an unerupted or developing tooth. This report concerns a nine-year-old boy who was diagnosed with maxillary sinusitis originating from a dentigerous cyst with supernumerary teeth. The boy visited our pediatric clinic presenting with rhinorrhea and nasal obstruction and was initially diagnosed with maxillary sinusitis only. With antibiotic treatment, his symptoms seemed to improve, but after 2 months, he came to our clinic with left facial swelling with persistent rhinorrhea and nasal obstruction. Radiographic examinations of the sinuses were performed, and he was diagnosed with maxillary sinusitis originating from a dentigerous cyst with supernumerary teeth. After a surgical procedure involving the removal of the dentigerous cyst with supernumerary teeth, the symptoms of sinusitis gradually diminished. There are only very few cases in the pediatric medical literature that remind us that odontogenic origin can cause maxillary sinusitis in children. Our patient can act as a reminder to general pediatricians to include dentigerous cysts in the differential diagnosis of maxillary sinusitis.

• Pediatric Infection and Vaccine
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• v.25 no.3
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• pp.148-155
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• 2018

Purpose: The purpose of this study was to investigate the clinical significance of Bacille Calmette-$Gu{\acute{e}}rin$ (BCG) site reaction in terms of diagnosis and outcome prediction in young children with Kawasaki disease (KD). Methods: The incidence of BCG site reaction in the respective age ranges was investigated in 1,058 patients who were admitted at Asan Medical Center between January 2006 and February 2017. The 416 patients under 18 months of age were enrolled as subjects for the analysis of the association between BCG site reaction and other laboratory and clinical findings. The analysis was performed separately in complete and incomplete KD groups. Results: The incidence rate of BCG site reaction was peaked at 6-12 months (83%) and decreased with increasing age after 12 months in 1,058 patients (P<0.001). The incidence rate was above 70% in KD aged less than 18 months and more frequent than those of cervical lymphadenopathy. The logistic regression analyses showed that the principal clinical findings including conjunctivitis (P=0.781), red lips/oral mucosa (P=0.963), rash (P=0.510), cervical lymphadenopathy (P=0.363), changes in extremities (P=0.283) and the coronary artery aneurysm (P=0.776) were not associated with the BCG site reaction. Conclusions: The BCG site reaction could be a useful diagnostic tool independent to principal clinical findings in KD developing in children aged <18 months, who underwent BCG vaccination. Outcome of KD patients was not different between groups with or without the BCG site reaction in both complete KD and incomplete KD.

• Journal of Microbiology
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• v.44 no.5
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• pp.548-555
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• 2006

FaeG is the key factor in the infection process of K88ad enterotoxigenic Escherichia coli (ETEC) fimbrial adhesin. In an attempt to determine the possibility of expressing recombinant FaeG with immunogenicity for a new safe and high-production vaccine in E. coli, we constructed the recombinant strain, BL21 (DE3+K88), which harbors an expression vector with a DNA fragment of faeG, without a signal peptide. Results of 15% SDS-polyacrylamide slab gel analysis showed that FaeG can be stably over-expressed in BL21 (DE3+K88) as inclusion bodies without FaeE. Immunoglobulin G (IgG) and M (IgM) responses in pregnant pigs, with boost injections of the purified recombinant FaeG, were detected 4 weeks later in the sera and colostrum. An in vitro villius-adhesion assay verified that the elicited antibodies in the sera of vaccinated pigs were capable of preventing the adhesion of K88ad ETEC to porcine intestinal receptors. The protective effect on the mortality rates of suckling piglets born to vaccinated mothers was also observed one week after oral challenge with the virulent ETEC strain, $C_{83907}$ (K88ad, $CT^+,\;ST^+$). The results of this study proved that the adhesin of proteinaceous bacterial fimbriae or pili could be overexpressed in engineered E. coli strains, with protective immune responses to the pathogen.

• Pediatric Infection and Vaccine
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• v.22 no.3
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• pp.210-215
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• 2015

Macrophage activation syndrome (MAS) is a rare complication in systemic lupus erythematosus (SLE) that can be triggered by infections. Due to the fact that MAS may mimic clinical features of underlying rheumatic disease, or be confused with an infectious complication, its detection can prove challenging. This is particularly true when there is an unknown/undiagnosed disease; and could turn into an even greater challenge if MAS and SLE are combined with a viral infection. A-14-year-old female came to the hospital with an ongoing fever for 2 weeks and a painful facial skin rash. Hepatomegaly, pancytopenia, increased aspartate aminotransferase, elevated serum ferritin and lactate dehydrogenase were reported. No hemophagocytic infiltration of bone marrow was reported. The patient was suspected for hemophagocytic lymphohistiocytosis. Her skin rashes were eczema herpeticum, which is usually associated with immune compromised conditions. With the history of oral ulcers and malar rash, positive ANA and low C3, C4 and the evidence of hemolytic anemia, she was diagnosed as SLE. According to the diagnostic guideline for MAS in SLE, she was diagnosed MAS as well, activated by acute HSV infection. After administering steroids and antiviral agent, the fever and skin rash disappeared, and the abnormal laboratory findings normalized. Therefore, we are reporting a rare case of MAS triggered by acute HSV infection as the first manifestation of SLE.

• Korean Journal of Veterinary Service
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• v.42 no.1
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• pp.39-42
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• 2019

Tetanus is an acute, often fatal, and infectious disease of all species of domestic animals caused by the neurotoxin of Clostridium tetani (C. tetani). This disease is usually known to develop after microbial contamination in the deep or penetrating wound sites. In February 2017, a farmer who was raising 76 cows injected foot and mouth disease vaccine to three or more cows with one syringe. Their clinical symptoms were observed 2 to 16 days after the vaccination. The initial symptoms were stiffness, rigidity of the neck and limbs, pricked ears, and prolapse of the third eyelid. Subsequently, there was recumbency with extension of the limbs, convulsions and opistotonus and the affected 20 cows were all died. Two dead cows were submitted to Animal and Plant Quarantine Agency for disease diagnosis. At necropsy, a focal edematous abscess of 15 to 20 cm in diameter was grossly observed in the subcutaneous and intramuscular tissue of scapular region and filled with a large amount of greenish pus. The feed was full in oral cavity and slightly observed in the trachea and lobes of lung. Histopathologically, focal granulomatous nodules with eosinophilic materials in the tissue were observed. In the lung, aspiration pneumonia and gram (+) bacteria were seen. The C. tetani was isolated in samples anaerobically cultured using reinforced clostridial medium and identified by PCR. To our knowledge, no previous outbreak of tetanus in cattle has affected such a high number of animals; neither has it been associated with misuse of the same syringe and needle to administer multiple individuals.

• IMMUNE NETWORK
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• v.21 no.2
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• pp.14.1-14.17
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• 2021

Scrub typhus develops after the individual is bitten by a trombiculid mite infected with Orientia tsutsugamushi. Since it has been reported that pneumonia is frequently observed in patients with scrub typhus, we investigated whether intranasal (i.n.) vaccination with the outer membrane protein of O. tsutsugamushi (OMPOT) would induce a protective immunity against O. tsutsugamushi infection. It was particular interest that when mice were infected with O. tsutsugamushi, the bacteria disseminated into the lungs, causing pneumonia. The i.n. vaccination with OMPOT induced IgG responses in serum and bronchoalveolar lavage (BAL) fluid. The anti-O. tsutsugamushi IgA Abs in BAL fluid after the vaccination showed a high correlation of the protection against O. tsutsugamushi. The vaccination induced strong Ag-specific Th1 and Th17 responses in the both spleen and lungs. In conclusion, the current study demonstrated that i.n. vaccination with OMPOT elicited protective immunity against scrub typhus in mouse with O. tsutsugamushi infection causing subsequent pneumonia.