• Pediatric Infection and Vaccine
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• v.13 no.2
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• pp.147-155
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• 2006

Purpose : The purpose of this study is to evaluate epidemiological data of pathogens obtained from stool exams and compare them with the clinical course in pediatric patients with symptoms of acute gastroenteritis. Methods : Subjects were selected from patients presenting with symptoms of acute gastroenteritis who visited the outpatient clinic or who were admitted to the Dankook University Hospital from December of 2004 to December of 2005. Stool exams for 17 pathogens was performed. RT-PCR was used to detect norovirus and enzyme-linked immunoabsorbant assay (ELISA) was used to detect rotavirus, adenovirus and astrovirus in the subjects stool samples. Ten different species of bacteria(Salmonella spp., Shigella spp., Clostridium perfrigens, Campylobacter spp., Escherichia coli, Vibrio spp., Staphylococcus aureus, Bacillus cereus, Yersinia spp., and L. monocytogenes) were each selectively cultivated and enzyme immunoassays(EIA) was used to test for antigens for C. parvum, E. histolytica and G. lamblia. Retrospective chart review was performed for comparisons of clinical manifestations. Results : A total of 215 subjects was selected and of these 89 cases(41.4%) showed positive results for at least one pathogen. Male to female ratio was 1.3:1. Age distribution showed 4 cases less than one month(4.5%), 4 cases from 1~2 months(4.5%), 24 cases from 3~12 months(26.7%), 47 cases form 13~48 months(52.8%), 10 cases greater than 48 months (21.2%). Viruses showed the greatest proportion of cases with 68 subjects(77.5%), of these rotavirus being the most commonly reported in 50 cases. Bacteria was identified in 26 cases (29.2%), of these nontyphoidal salmonella was noted in 10 cases. Protozoa followed with 21 cases(23.6%), of these C. parvum was noted in 11 cases and G. lamblia was noted in 10 cases. Mixed infections with more than two pathogens were seen in 22 cases(24.7%), of these viral infection with accompanying parasitic infection was seen in 12(54.5%) cases. Conclusion : In this study we examined various pathogens known to cause acute gastroenteritis in children. Further studies for various pathogens can provide useful information for management of the acute gastroenteritis.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.88-89
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• 2013

A variety of influenza A viruses from animal hosts are continuously prevalent throughout the world which cause human epidemics resulting millions of human infections and enormous industrial and economic damages. Thus, early diagnosis of such pathogen is of paramount importance for biomedical examination and public healthcare screening. To approach this issue, here we propose a fully integrated Rotary genetic analysis system, called Rotary Genetic Analyzer, for on-site detection of influenza A viruses with high speed. The Rotary Genetic Analyzer is made up of four parts including a disposable microchip, a servo motor for precise and high rate spinning of the chip, thermal blocks for temperature control, and a miniaturized optical fluorescence detector as shown Fig. 1. A thermal block made from duralumin is integrated with a film heater at the bottom and a resistance temperature detector (RTD) in the middle. For the efficient performance of RT-PCR, three thermal blocks are placed on the Rotary stage and the temperature of each block is corresponded to the thermal cycling, namely $95^{\circ}C$ (denature), $58^{\circ}C$ (annealing), and $72^{\circ}C$ (extension). Rotary RT-PCR was performed to amplify the target gene which was monitored by an optical fluorescent detector above the extension block. A disposable microdevice (10 cm diameter) consists of a solid-phase extraction based sample pretreatment unit, bead chamber, and 4 ${\mu}L$ of the PCR chamber as shown Fig. 2. The microchip is fabricated using a patterned polycarbonate (PC) sheet with 1 mm thickness and a PC film with 130 ${\mu}m$ thickness, which layers are thermally bonded at $138^{\circ}C$ using acetone vapour. Silicatreated microglass beads with 150~212 ${\mu}L$ diameter are introduced into the sample pretreatment chambers and held in place by weir structure for construction of solid-phase extraction system. Fig. 3 shows strobed images of sequential loading of three samples. Three samples were loaded into the reservoir simultaneously (Fig. 3A), then the influenza A H3N2 viral RNA sample was loaded at 5000 RPM for 10 sec (Fig. 3B). Washing buffer was followed at 5000 RPM for 5 min (Fig. 3C), and angular frequency was decreased to 100 RPM for siphon priming of PCR cocktail to the channel as shown in Figure 3D. Finally the PCR cocktail was loaded to the bead chamber at 2000 RPM for 10 sec, and then RPM was increased up to 5000 RPM for 1 min to obtain the as much as PCR cocktail containing the RNA template (Fig. 3E). In this system, the wastes from RNA samples and washing buffer were transported to the waste chamber, which is fully filled to the chamber with precise optimization. Then, the PCR cocktail was able to transport to the PCR chamber. Fig. 3F shows the final image of the sample pretreatment. PCR cocktail containing RNA template is successfully isolated from waste. To detect the influenza A H3N2 virus, the purified RNA with PCR cocktail in the PCR chamber was amplified by using performed the RNA capture on the proposed microdevice. The fluorescence images were described in Figure 4A at the 0, 40 cycles. The fluorescence signal (40 cycle) was drastically increased confirming the influenza A H3N2 virus. The real-time profiles were successfully obtained using the optical fluorescence detector as shown in Figure 4B. The Rotary PCR and off-chip PCR were compared with same amount of influenza A H3N2 virus. The Ct value of Rotary PCR was smaller than the off-chip PCR without contamination. The whole process of the sample pretreatment and RT-PCR could be accomplished in 30 min on the fully integrated Rotary Genetic Analyzer system. We have demonstrated a fully integrated and portable Rotary Genetic Analyzer for detection of the gene expression of influenza A virus, which has 'Sample-in-answer-out' capability including sample pretreatment, rotary amplification, and optical detection. Target gene amplification was real-time monitored using the integrated Rotary Genetic Analyzer system.

• Pediatric Infection and Vaccine
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• v.24 no.2
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• pp.95-101
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• 2017

Purpose: Acute bacterial gastroenteritis (ABG) can cause more severe symptoms than acute viral gastroenteritis in children. This study was aimed at determining the etiologic trends and to examine the clinical characteristics of ABG in children. Methods: We sent stool samples from the children with acute gastroenteritis who were treated at a secondary hospital located in Seoul, Korea between January 2011 and December 2014 to Seoul Metropolitan Government Research Institute of Public Health and Environment to find the causative organisms. Clinical characteristics of patient were analyzed through a medical records review. Results: Out of 664 stool samples, 183 (27.6%) yielded bacterial pathogens. Staphylococcus aureus was the most common bacterial pathogen, found in 72 cases (39.3%), even though it was only tested for since 2012. The monthly isolation rate was the highest (24.6%) in August. The isolation rate of Campylobacter spp. by patient's age group was high (16.7%) in the 12- to 18-year-age group (P=0.04). In patients with bloody stool, Campylobacter spp. was the most commonly isolated (31.0%, P=0.04). When comparing C-reactive protein, the Salmonella spp.- or Campylobacter spp.-isolated group showed higher values than the S. aureus- or pathogenic Escherichia coli-isolated group ($5.7{\pm}0.6mg/dL$ vs. $2.1{\pm}0.3mg/dL$, P<0.01). Conclusions: S. aureus, Salmonella spp., pathogenic E. coli, and Campylobacter spp. were important pathogens of ABG among children. Considering the differences in pathogens found according to age, a clinical symptom and inflammation index might be helpful in assuming the causative organism.