• Biomedical Science Letters
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• v.27 no.4
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• pp.195-207
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• 2021

Methicillin-resistant Staphylococcus aureus (MRSA) is a bacterial pathogen capable of causing human diseases, such as soft tissue infection, bacteremia, endocarditis, toxic shock syndrome, pneumonia, and sepsis. Although the incidence rate of diseases caused by MRSA has declined in recent years, these diseases still pose a clinical threat due to their consistently high morbidity and mortality rates. However, the role of virulence factors in staphylococcal infections remains incompletely understood. Methicillin resistance, which confers resistance to all β-lactam antibiotics in cellular islets, is mediated by the mecA gene in the staphylococcal cassette chromosome mec (SCCmec). Differences in SCCmec types and differences in their sizes and structures serve epidemiological purposes and are used to differentiate between hospital-associated (HA)-MRSA and community-associated (CA)-MRSA. Some virulence factors of S. aureus are also providing a distinction between HA-MRSA and CA-MRSA. These factors vary depending on the presence of toxins, adhesion, immune evasion, and other virulence determinants. In this review, we summarized an overview of MRSA such as resistance mechanisms, SCCmec types, HA- and CA-MRSA, and virulence factors that enhance pathogenicity or MRSA epidemiology, transmission, and genetic diversity.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.186-186
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• 1996

Streptococcus pneumoniae (pneumococcus), the most common cause of bacterial pneumonia, has an ample polysaccharide(PS) capsule that is highly antigenic and is the source of PS vaccine. This investigation was undertaken to optimize the culture conditions for the production of capsular PS by type 1 pneumococcus. Among several culture media, brain heart infusion (BHI) and Casitone based media were found to support luxuriant growth of pneumococcus type 1 at the same level. Because BHI medium is rather expensive and more complex than the Casitone based media, the Casitone based media was used to study optimization of the culture condition. The phase of growth which accomodated maximum PS production was logarithmic phase. Concentrations of glucose greater than 0.2% did not enhance growth or PS production. Substitution of nitrogen sources with other resources or supplemention of various concentrations of metal ion (with the exception of calcium ion) had adverse effects on growth and PS production. On the other hand, low level aeration was beneficial for increased PS production. Addition of 3 mg/I concentration of methionine, phenylalanine, and threonine were found to enhance growth and PS production. The synergistic effect of all the favorable conditions observed in pneumococcal growth assays provided a two-fold cumulative increase in capsular PS production.

• Clinical and Experimental Pediatrics
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• v.48 no.11
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• pp.1193-1200
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• 2005

Purpose : Invasive bacterial infection is a major cause of morbidity and mortality in children. Previously, we reported etiology of invasive infections in healthy children in 1985-1995. This study was performed to update etiology of invasive bacterial infections in the previously healthy children. Methods : We reviewed medical records of 98 episodes of invasive bacterial infections in immunocompetent children at the Seoul National University Children's Hospital in 1996-2004. Results : The frequent pathogens identified over all age groups were Streptococcus pneumoniae (33%) and Staphylococcus aureus(33%). The proportion of Salmonella species and Haemophilus influenzae has been declined to 4% each from 23% and 14%, respectively, compared to previous study. S. agalactiae was the most common isolate in the infants ${\leq}3$ months. Among the infants and children aged 3 months to 2 years and children of 2-5 years, S. pneumoniae(57%, 52%, respectively, in each group) was the most common isolates followed by S. aureus(17% and 24%, respectively). S. aureus was the most common isolates(73%) in children >5 years. Primary bacteremia was the most common clinical diagnosis(27%). S. pneumoniae was responsible for 42% of primary bacteremia, 50% of meningitis, and 69% of bacteremic pneumonia and empyema. S. aureus accounted for 80% of bone and joint infections. The case fatality rate was 8.1% for all invasive infections. Conclusion : We reviewed frequency of bacterial agents of invasive infections in children. The data may be useful for pediatricians to select adequate empirical antibiotics in the management of invasive bacterial infections.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.60 no.2
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• pp.239-247
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• 2015

This experiment was conducted to obtain the have higher contents of pharmaceutical constituents as well as higher yield from colchicine induced diploid and tetraploid extracts of Platycodon grandiflorum. In order to determine the biological activity, this study was focused to evaluate the cytotoxicity, antimicrobial on the bronthus disease bacteria, antioxidant enzyme activity of diploid and tetraploid extracts in P. grandiflorum. The activities of antioxidant enzyme according to different solvent extracts were measured as superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and ascorbate peroxidase (APX). The cytotoxicity of methanol extracts of P. grandiflorum showed significant differences between tetraploid and diploid. That is, the cytotoxic effect against human cancer cell was higher in tetraploid than in diploid. At all extracts concentration, tetraploid samples showed high toxicity and the $IC_{50}$ (concentration causing 50% cell death) value showed the highest on HCT-116 cell ($105.91{\mu}g/mL$), and exhibited significant activity against the Hep 3B cell ($140.67{\mu}g/mL$), SNU-1066 cell ($154.01{\mu}g/mL$), Hela cell ($158.37{\mu}g/mL$), SNU-601 cell ($182.67{\mu}g/mL$), Calu-6 cell ($190.42{\mu}g/mL$), MCF-7 cell ($510.19{\mu}g/mL$). Antimicrobial activities of diploid P. grandiflorum were relatively low compared to tetraploid P. grandiflorum on most of the bacterial strains. In tetraploid P. grandiflorum, K. pneumoniae showed the clear zone formation (18~19 mm) of growth inhibition, followed by the clear zone formation of 13~15 mm on C. diphtheria and S. pyogenes. The antimicrobial activities in diploid P. grandiflorum were the highest on K. pneumonia (14~15 mm), and showed the clear zone formation of 11~12 mm on C. diphtheria and 12~13 mm on S. pyogenes. The antimicrobial activity is thought to look different depending on the bacterial strains and the polyploidy of P. grandiflorum. The root extract of P. grandiflorum had the highest (97.2%) SOD enzyme activity in ethyl acetate partition layer of tetraploid while water partition layer of diploid showed the lowest (48.6%) SOD enzyme activity. The activity of CAT showed higher values in the root of tetraploid than in the diploid of P. grandiflorum in all partition layers except butyl alcohol. The activities of APX and POD showed higher values in the root of tetraploid than in the diploid of P. grandiflorum in all fraction solvents except water layer. These results indicate that the tetraploid P. grandiflorum can be used as a source for developing cytotoxic agent and antimicrobials which can act against bronchus diseases bacterial strains.

• Journal of Microbiology and Biotechnology
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• v.27 no.8
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• pp.1529-1538
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• 2017

Klebsiella pneumoniae is an opportunistic and clinically significant emerging pathogen. We investigated the relative roles of Toll-like receptor (TLR) 2 and TLR4 in initiating host defenses against K. pneumoniae. TLR2 knockout (KO), TLR4 KO, TLR2/4 double KO (DKO), and wild-type (WT) mice were inoculated with K. pneumoniae. Mice in each group were sacrificed after either 12 or 24h, and the lungs, liver, and blood were harvested to enumerate bacterial colony-forming units (CFU). Cytokine and chemokine levels were analyzed using enzyme-linked immunosorbent assay and real-time PCR, and pneumonia severity was determined by histopathological analysis. Survival was significantly shortened in TLR4 KO and TLR2/4 DKO mice compared with that of WT mice after infection with $5{\times}10^3CFU$. TLR2 KO mice were more susceptible to infection than WT mice after exposure to a higher infectious dose. Bacterial burdens in the lungs and liver were significantly higher in TLR2/4 DKO mice than in WT mice. Serum $TNF-{\alpha}$, MCP-1, MIP-2, and nitric oxide levels were significantly decreased in TLR2/4 DKO mice relative to those in WT mice, and TLR2/4 DKO mice showed significantly decreased levels of $TNF-{\alpha}$, IL-6, MCP-1, and inducible nitric oxide synthase mRNA in the lung compared with those in WT mice. Collectively, these data indicate that TLR2/4 DKO mice were more susceptible to K. pneumoniae infection than single TLR2 KO and TLR4 KO mice. These results suggest that TLR2 and TLR4 play cooperative roles in lung innate immune responses and bacterial dissemination, resulting in systemic inflammation during K. pneumoniae infection.

• Neonatal Medicine
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• v.15 no.1
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• pp.61-66
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• 2008

Purpose : The purpose of this study was to describe the epidemiologic features of febrile illnesses in newborns and to predict the risk of serious infections in this population. Methods : A retrospective study was conducted on 123 full-term infants <30 days of age with an axillary temperature >38$^{\circ}C$ who were hospitalized between 2000 and 2006. Neonates with prenatal risk factors, congenital anomalies, antibiotic administration prior to admission to the hospital, or suspected hospital-acquired infections were excluded. We evaluated the symptoms, physical examination findings, laboratory data, and clinical course between the high- and low-risk groups for serious infections. Results : The high-risk group included 30 infants with the following diagnoses in order of frequency: aseptic meningitis, urinary tract infection, bacterial meningitis, infectious enteritis, sepsis concomitant with disseminated intravascular coagulopathy, bacteremia, pneumonia, cellulitis, and omphalitis. Leukocytosis and thrombocytopenia were statistically different between the two groups. Factors, such as moaning signs, seizures, body temperature, and pulse rate were statistically significant. Conclusion : Unlike previous studies, we included newborns with clinical bacterial infections and aseptic meningitis as the high-risk group. Leukocytosis, thrombocytopenia, moaning signs, seizures, and changes in vital signs were considered useful predictors for identifying febrile neonates at high-risk for serious infections in spite of a difference in the definition of serious infection.

• Korean Journal of Clinical Laboratory Science
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• v.53 no.3
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• pp.225-232
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• 2021

This study sought to investigate the distribution, antimicrobial resistance rate, and bacterial co-infection frequency of non-tuberculous mycobacteria (NTM) in a single center in Incheon, South Korea. A total of 8,258 specimens submitted for tuberculosis (TB)/NTM real-time PCR tests during the years 2015 to 2020 were retrospectively reviewed. In total, 296 specimens (3.6%) were NTM positive, and the positivity increased from 2.5% (30/1,209) in 2015 to 3.8% (66/1,740) in 2020. Of 296 NTM specimens, 54.7% (162/296) were identified as the Mycobacterium avium complex (MAC) followed by the Mycobacterium abscessus complex (MABC) 20.9% (62/296), M. fortuitum 6.4% (19/296) and M. flavescens 3.4% (10/296). Of the NTM-positive specimens, 76.7% (227/296) were tested for drug resistance. The results showed multidrug-resistant NTM in 40.1% (91/227) and extensively drug-resistant NTM in 59.9% (136/227) of these specimens. Of the 145 isolates taken for bacterial culture, bacteria/fungi co-infection with NTM accounted for 43.4% (63/145), in which the most common bacterial species was Klebsiella pneumonia (23.8%, 15/63). This study is the first report on the distribution and antimicrobial resistance of NTM in Incheon. As the proportion of NTM infections increases, active treatment and thorough infection control are required for effective management.

• The Journal of Pediatrics of Korean Medicine
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• v.12 no.1
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• pp.111-131
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• 1998

1. In oriental medicine, the case of sinusitis can be explained, not only external invasion such as PUNG HAN(wind-cold), PUNG YUL(wind-hot), SHUP YUL(damp-heat), but also functional disorder of internal organ such as spleen(脾), lung(肺), kidney(腎) The western medicine classified the cause of sinusitis as two factors. That is bacterial infection factor-Haemophilus influenza, streptococcus pyogeues, streptococcus pneumonia- and viral infection factor-Rhinovirus, parainfluenza, Echo28, Coxsacki21, Sinusitis is complicated to allergic rhinitis, chronic otitis media purulent, chronic tonsilitis, sinubronchitis. On the condition of nasal septum deformity, turbinates deformity, nasal septum deviation, sinusitis can be developed. the predisposing factors of sinusitis is swimming, air pollution, malnutrition, shortage of immunity.2. According to survey, sinusitis occurred that children from 4 to 12 years old and from 5 to 7 years old occupied 70% 3. From the past history data, they experienced chronic tonsillar hypertropy(20%), otitis media, atopic dermatitis, allergic rhinitis, bronchial asthma, pneumonia, bronchiolitis, chronic sore throat, urticaria, milk allergy in sequence. 4. the symptoms of sinusitis is nasal obstruction, postnasal dripping, purulunt(yellow)or white discharge, cough, nose bleeding in sequence. nasal obstruction take the portion of 95%, postnasal dripping 65%, night time or early morning cough 60%. 5. The suffering period of sinusitis is 6 month minimum, 4 years maximum, most cases are included in a year. The suffering period of children was shorter than adult. 6. Diagnosis depend on inspection of nasal cavity, postnasal dripping, X-ray finding. 75% of patient(15case) showed both maxillary sinusitis, 25%(5cases) showed left or right maxillary sinusitis. 7. Treatment of oriental medicine, consist of Herb-medicine, acupuncture and exposing of Lazer beam. Kamihyunggyeyungyotang(加味荊芥蓮翹湯) is administered mainly as the medical therapy, Kamigwaghyangjeungkisan(加味藿香正氣散) Kimizwakwieum(加味左歸飮), Kamihyangsosan(加味香蘇散) is administered for a additional symptoms which occurred by influenza recurrence. Kamijeonxibackchulsan(加味錢氏白朮散) is administered to treat gastro-intestine trouble patients who have sinusitis. 8. The period of treatment is varied with patient conditions and X-ray finding. The minimal period is 35days, maximal period is 202days. So it took about 86days in average and about 50% of patient(10cases) is recovered in one or two month.

• Korean Journal of Veterinary Service
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• v.42 no.4
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• pp.201-216
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• 2019

Porcine reproductive and respiratory syndrome (PRRS) is characterized by reproductive failure in sows and respiratory distress in all age pigs. Porcine respiratory disease complex (PRDC) is a disease caused by opportunistic bacterial infection secondary to a weakened immune system by a preceding respiratory infection. In this study, we tried to compare the immune responses in PRRS and PRDC groups to clearly characterize the disease severity. Eighty-five pigs were infected with various Korean field PRRS virus strains. Infected animals were classified into PRRS (n=32) and PRDC (n=53) groups based on lung lesions such as interstitial pneumonia, suppurative pneumonia, and pleuropneumonia. The immune cell population of bronchoalveolar lavage cells (BALc) was evaluated on 14 and 28 days post infection (dpi) and PMBC cytokine expression was measured on 0, 3, 7, 14 dpi to investigate early inflammatory reactions. Pulmonary lesion severity was negatively correlated with alveolar macrophage (AM) in both PRRS and PRDC groups on 14 and 28 dpi. AM in BALc was less populated in PRDC group on 28 dpi compared to PRRS group. AM in BALc was significantly less populated in PRDC group on 28 dpi compared to 14 dpi. In addition, cytotoxic T lymphocyte (CTL) in BALc was higher populated in PRDC group on 14 dpi and 28 dpi compared to PRRS group. In the case of PBMC cytokine TNF-α, IFN-α, IL-1β, IFN-γ, FoxP3, and IL-2, the PRRS group showed higher expression than the PRDC group on 7 dpi, 14 dpi, 7 dpi, 14 dpi, 14 dpi, and 14 dpi, respectively. On the other hand, in the case of IFN-β, IL-6, IL-8, IL-4, and IL-17, the PRDC group showed higher PBMC cytokine expression at 14 dpi, 7 dpi, 14 dpi, 3 dpi, and 3 dpi, respectively, than the PRRS group. Based on these results, our study could characterize differential immune responses in pigs with PRRS or PRDC.

• 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.