• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.4
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• pp.640-651
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• 1997

This study was performed to examine the distribution patterns, ecological characteristics and celluar fatty acid compositions of marine bacteria in Suyeong Bay. During study periods, total cell count (TC) and viable cell count (VC) were $10^7-10^8/m\ell\;and\;10^4-10^6\;cfu/m\ell$, respectively. The temporal variations of TC showed similar patterns between surface and bottom layer, but the VC at bottom decreased gradually from winter to summer. Among the 303 bacterial strains isolated in the study area, which belong to 10 genus types, Pseudomonas spp., $(32.3\%)$, Acinetobader sup. $(19.1\%)$, Vibrio spp. $(11.2\%)$, Flovobacterium spp. $(10.6\%)$ and Bacillus spp. $(7.9\%)$ were dominant. Thirty-one fatty acids were detected from Pseudomonas spp. and Bacillus spp., which were the most predominated among Gram positive and Gram negative bacteria. Celluar fatty acid compositions of Bacillus spp. were relatively simple compared to those of Pseudomonas spp.. Relatively high ratio of monounsaturated forms were detected in Pseudomonas spp. while branched types were dominant in those of Bacillus spp.. Hydroxy and cyclopropane fatty acid were detected only in the cellular fatty acid of Pseudomonas spp.. Cellular fatty acid compositions of Pseudomonas spp. revealed relatively high percentage of $C_{16:1},\;C_{17:1},\;C_{18:1}\;and\;C_{16:0}$, While Bacillus spp. predominated $C_{16:0}\;iso\;C_{16:0}\;anteiso,\;C_{17:0}\;anteiso\;and\;C_{16:1}$.

• Clinical and Experimental Pediatrics
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• v.48 no.11
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• pp.1206-1211
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• 2005

Purpose : Pneumococcal protein vaccine based on pneumococcal surface protein A (PspA) is in development with the potential to offer a broad range of protection against different strains. PspA elicits protection in mice against fatal sepsis as well as carriage and lung infection. This study was performed to investigate the frequency of PspA families among Streptococcus pneumoniae recovered from Korean children and adults. Methods : A total of 89 pneumococcal isolates was included in the study. They were capsule serotyped by the slide agglutination assay with commercial antisera. PspA families were determined with polymerase chain reaction using the pair of primers for family 1 and family 2. Results : Seventeen pneumococcal serotypes were found in a total of 89 isolates. PspA typing was able to ascertain 79 of the 89 isolates (88.8 percent). Among these, 20 (22.5 percent) isolates were family 1 PspA, 59 (66.3 percent) were family 2. Moreover, because 9 (10.1 percent) isolates were of positive reactions for both, families 1 and 2 primers, the potential coverage of PspA vaccine was 98.9 percent. PspA families were not associated with age group, source of isolates, or penicillin susceptibility. However, the relative distribution of family 1 isolates to family 2 isolates was significantly different over capsular serotypes. Conclusion : The finding that 98.9 percent of Korean isolates belonging to PspA families 1 and 2 support the hypothesis that a human PspA vaccine covering a few PspA families could be broadly effective. The monitoring of the PspA families derived from large population-based isolates will be necessary in the context of vaccine development.

• Microbiology and Biotechnology Letters
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• v.40 no.2
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• pp.92-97
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• 2012

Antimicrobial peptides (AMPs) are important components of living organisms acting against Gram-negative and Gram-positive bacterial and fungal pathogens. Cathelicidin human peptides have a variety of biological activities that can be used in clinical applications. AMPs are not produced naturally in large quantities, and chemical synthesis is also economically impractical, especially for long peptides. Therefore, as an alternative, heterologous expression of AMPs by recombinant techniques has been studied as a means to reduce production costs. E. coli is an excellent host for the expression of AMPs, as well as other recombinant proteins, because of the low cost involved and its easy manipulation. However, overexpression of AMPs in E. coli has been shown to cause difficulties resulting from the toxicity of the subsequently produced AMPs. Therefore, fusion expression was theorized to be a solution to this problem. In this study, AMPs were expressed as fused proteins with the glutathione S-transferase (GST) binding protein to protect against the toxicity of AMPs when expressed in E. coli. The LL37, and hybrid gaegurin and LL37 (GGN4(1-16)-LL37(17-32), which we designated as GL32, peptides were expressed as GST-fusion proteins in E. coli and the fusion proteins were then purified by affinity columns. The purified peptides were obtained by removal of GST and were confirmed by western blot analysis. The purified antimicrobial peptides then demonstrated antimicrobial activities against Gram-negative and Gram-positive bacterial strains.

• Journal of Microbiology and Biotechnology
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• v.28 no.11
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• pp.1928-1936
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• 2018

Recently, human infections caused by severe fever with thrombocytopenia syndrome virus (SFTSV), which can lead to fatality, have dramatically increased in East Asia. With the unavailability of vaccines or antiviral drugs to prevent and/or treat SFTSV infection, early rapid diagnosis is critical for prevention and control of the disease. Here, we report the development of a simple, rapid and sensitive portable detection method for SFTSV infection applying reverse transcription-loop mediated isothermal amplification (RT-LAMP) combined with one-pot colorimetric visualization and electro-free reaction platform. This method utilizes a pocket warmer to facilitate diagnosis in a resource-limited setting. Specific primers were designed to target the highly-conserved region of L gene of SFTSV. The detection limit of the RT-LAMP assay was approximately $10^0$ viral genome copies from three different SFTSV strains. This assay exhibited comparable sensitivity to qRT-PCR and 10-fold more sensitivity than conventional RT-PCR, with a rapid detection time of 30 to 60 minutes. The RT-LAMP assay using SFTSV clinical specimens has demonstrated a similar detection rate to qRT-PCR and a higher detection rate compared to conventional RT-PCR. Moreover, there was no observed cross-reactive amplification of other human infectious viruses including Japanese Encephalitis Virus (JEV), Dengue, Enterovirus, Zika, Influenza and Middle East Respiratory Syndrome Coronavirus (MERS-CoV). This highly sensitive, electro- and equipment-free rapid colorimetric visualization method is feasible for resource-limited SFTSV field diagnosis.

• Journal of Microbiology and Biotechnology
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• v.21 no.5
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• pp.509-514
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• 2011

This study was conducted to investigate the phenotypic and genotypic characteristics of Korean isolates of Cronobacter spp. (Enterobacter sakazakii). A total of 43 Cronobacter spp., including 5 clinical isolates, 34 food isolates, 2 environmental isolates, and 2 reference strains (C. sakazakii ATCC 29004 and C. muytjensii ATCC51329) were used in this study. Korean isolates of Cronobacter spp. were divided into 11 biogroups according to their biochemical profiles and 3 genomic groups based on the analysis of their 16S rRNA gene sequences. Biogroups 1 and 2 contained the majority of isolates (n=26), most of which were contained in 16S rRNA cluster 1 (n=34). Korean isolates of Cronobacter spp. showed diverse biochemical profiles. Biogroup 1 contained C. sakazakii GIHE (Gyeonggido Research Institute of Health and Environment) 1 and 2, which were isolated from babies that exhibited symptoms of Cronobacter spp. infection such as gastroenteritis, sepsis, and meningitis. Our finding revealed that Biogroup 1, C. sakazakii, is more prevalent and may be a more pathogenic biogroup than other biogroups, but the pathogenic biogroup was not represented clearly among the 11 biogroups tested in this study. Thus, all biogroups of Cronobacter spp. were recognized as pathogenic bacteria, and the absence of Cronobacter spp. in infant foods should be constantly regulated to prevent food poisoning and infection caused by Cronobacter spp.

• Pediatric Infection and Vaccine
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• v.27 no.2
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• pp.90-101
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• 2020

Purpose: The multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) test developed recently can help detect enteric pathogens of acute gastroenteritis (AGE). This study aimed to investigate the epidemiology of pathogens in children with AGE using the multiplex RT-PCR. Methods: From May 2015 to June 2018, multiplex RT-PCR tests were performed to identify pathogens in the feces of pediatric patients diagnosed with AGE at a secondary hospital in Seoul, Korea. Results: Of the 1,366 stool samples examined for viral pathogens, 483 (35.3%) tested positive for ≥1 pathogen. Group A rotavirus (RV) was detected in 106 cases (7.8%). The positivity rate increased annually from 3.0% (8/263) to 16.7% (48/288) and surged in 2018 (P<0.001). Norovirus (NoV) GII was the most common viral pathogen (263/1,366, 19.3%), and the positivity rate did not increase during the 3 years. Of the 304 stool samples tested for bacterial pathogens, Campylobacter spp. was the most common bacterial pathogen (32/304, 10.5%), followed by Clostridium difficile (22/304, 7.2%) and Salmonella spp. (17/304, 5.6%). The positivity rate of these bacterial pathogens did not change significantly during the study period. Conclusions: NoV GII is the main pathogen in childhood AGE since the introduction of RV vaccine, yet the number of rotavirus-infected patients increased during our study, especially in 2018. Therefore, further research is needed including the possibility of emergence of novel RV strains. Campylobacter spp. is the predominant cause of bacterial AGE in children. For proper treatment, the clinical characteristics of the bacteria should be taken into consideration, and continuous monitoring is necessary.

• Pediatric Infection and Vaccine
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• v.10 no.2
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• pp.178-185
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• 2003

Purpose : Group A streptococci(GAS) was isolated from the patients with acute pharyngitis. Epidemiological studies using T typing and emm genotyping was performed for GAS and compared with the results of the carriers. Methods : Throat cultures were taken from 246 children(123 boys, 123 girls) from November, 2001 to May, 2002 who visited a pediatrician's office located in Jinju, Gyeongnam province. T types were identified with slide agglutination and emm genotypes were identified with DNA sequencing after amplification of emm genes. Results : One hundred thirty(52.8%) out of 246 children yielded beta-hemolytic streptococci, of which 96.1% were group A. Children from 4 to 7 years old comprised 70.4% of the GAS positive group. T12 were the most common(35.2%) and T non-typeable strains were the next(30.4%). emm12 was most frequent(28.5%), and emm75(18.7%), emm22(13.0%), emm2(12.2%), and emm8(8.1%) were relatively common. Conclusion : Since GAS is so highly prevalent in acute pharyngitis, indeed being half of the population, good clinical practice dictates the systematic employment of throat culture for acute pharyngitis before prescribing antibiotics in a pediatric setting. The distribution of the T antigens and emm genes showed similar pattern between the acute pharyngitis and the carriers.

• Asian Pacific Journal of Cancer Prevention
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• v.17 no.1
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• pp.285-287
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• 2016

Background: The efficacy of standard treatment of Helicobacter pylori (H. pylori) is declining because of antibiotic resistance. Clarithromycin resistance is also increasing in many Asian countries. The aim of this study was to determine the antibiotic susceptibility patterns of H. pylori infection and clinical association in Laos. Materials and Methods: A total of 329 Lao dyspeptic patients who underwent gastroscopy at Mahosot Hospital, Vientiane, Laos during December 2010-March 2012 were enrolled in this study. During gastroscopy, 4 biopsies were collected (2 each from the antrum and body) for CLO-test and histopathology. Only the positive CLO-test gastric tissues was stored at $-80^{\circ}C$ in a freezer until DNA was extracted and a GenoType$^{(R)}$HelicoDR test was conducted for detecting mutations in the rrl gene encoding 23S rRNA (clarithromycin resistance) and mutations in gyrA gene (fluoroquinolone resistance). Results: Of the total, 119 Lao patients (36.2%) were infected with H. pylori including 59 males (49.6%) and 60 females (50.4%) with a mean age of 46 years. Clarithromycin and fluoroquinolone resistance of H. pylori infection was demonstrated in 15 (12.6%) and 16 strains (13.4%) respectively. In clarithromycin resistance, the number of patients who had education above primary school and $BMI{\geq}25kg/m^2$ were significantly higher than those who had education below primary school and BMI<$25kg/m^2$ (23.1% vs 7.5%, P-value= 0.036 and 20.5% vs 8%, P-value= 0.048, respectively). In fluoroquinolone resistance, the number of lowland Lao was significantly higher than those of non-lowland (highland and midland) Lao ethnic groups (16.7% vs 0%, P-value= 0.039). Conclusions: H. pylori infections remain common in Laos. Clarithromycin and fluoroquinolone resistance with H. pylori infection are growing problems. Education above primary school and $BMI{\geq}25kg/m^2$ might be predictors for clarithromycin resistance and lowland Lao ethnicity might be predictors for fluoroquinolone resistance with H. pylori infection in Laos.

• Biomedical Science Letters
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• v.11 no.3
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• pp.259-266
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• 2005

Mast cells and goblet cells have been known to protect the host against parasites. In this study, we examined the response of the mast cells and goblet cells over a period of 6 weeks in the duodenum, jejunum and ileum of C3H/HeN and C57BL/6 mice infected with Echinostoma hortense (E. hortense). In addition, we investigated whether the worm recovery rate of uninfected mice (the control group) or E. hortense-infected mice (the experimental group) was associated with the number of mast cells and goblet cells. The worm recovery rate was higher in the C3H/HeN mice than in the C57BL/6 mice. The number of goblet cells significantly increased in the experimental group of the C3H/HeN and C57BL/6 mice compared with the control group of both strains (P<0.005). Worm recovery peaked 3 weeks after the infection of the C57BL/6 mice and at 2 weeks after the infection of the C3H/HeN mice, and it was higher in the duodenum than in the jejunum and ileum. However, the infected site in the intestine had no relation with worm expulsion. In the C3H/HeN and C57BL/6 mice, the number of goblet cells in the experimental group was significantly higher than that in the control group (P<0.005). The number reached a peak 2 weeks after the infection and it even increased in duodenum, jejunum and ileum. The increased number of goblet cells was retained 6 weeks after infection. The number of goblet cells was higher in the C3H/HeN mice than in the C57BL/6 mice (P<0.01). These results indicate that goblet cells are related with the worm expulsion. Furthermore, immunohistostaining of the antral intestinal walls for lectin showed the significant increase of the number of goblet cells in the experimental group (P<0.001). The high infection rate in the duodenum was found during the early infection. An increased infection rate in the jejunum and ileum was found 3 weeks after infection and the infection rate was higher in the C3H/HeN mice than in the C57BL/6 mice. Taken together, the present study indicates that goblet cells, rather than mast cells, may play critical roles in parasite expulsion.

• Microbiology and Biotechnology Letters
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• v.41 no.1
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• pp.88-95
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• 2013

Candida biofilms are self-organized microbial communities growing on the surfaces of host tissues and medical devices. These biofilms have been displaying increasing resistance against conventional antifungal agents. The roots of Scutellaria baicalensis have been widely used for medicinal purpose throughout East Asia. The aim of the present study was to evaluate the effect of S. baicalensis aqueous extract upon the preformed biofilms of 10 clinical C. albicans isolates, and assess the mechanism of the antibiofilm activity. Its effect on preformed biofilm was judged using an XTT reduction assay and the metabolic activity of all tested strains were reduced ($57.7{\pm}17.3$%) at MIC values. The S. baicalenis extract inhibited (1, 3)-${\beta}$-D-glucan synthase activity. The effect of S. baicalensis on the morphology of C. albicans was related to the changes in growth caused by inhibiting glucan synthesis; most cells were round and swollen, and cell walls were densely stained or ruptured. The anticandidal activity was fungicidal, and the extract also arrested C. albicans cells at $G_0/G_1$. The data suggest that S. baicalensis has multiple fatal effects on target fungi, which ultimately result in cell wall disruption and killing by inhibiting (1, 3)-${\beta}$-D-glucan synthesis. Therefore, S. baicalensis holds great promise for use in treating and eliminating biofilm-associated Candida infections.