• Pediatric Infection and Vaccine
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• 제4권1호
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• pp.73-78
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• 1997

목 적 : Escherichia coli (E. coli) O157은 설사, 출혈성대장염 등을 일으키며, 드물게 용혈성 요독증후군까지 일으키는 세균이다. 미국이나 유럽에서는 세균성설사의 2~3번째로 흔한 원인균이다. 우리나라는 이 세균감염이 거의 없는것으로 알려져 왔으나, 우리나라도 점차 햄버거와 같은 간이음식의 섭취가 늘어나, 이 세균감염이 생겼을 가능성이 있을 것으로 사료되어, 향후 이 세균에 대한 통상적인 변배양 검사의 필요성 여부를 알아보고자 하였다. 방 법 : 1996년 3월부터 1997년 2월까지 6개월 이상된 소아설사 환아의 변배양 검체를 대상으로 하였다. Sorbitol-MacConkey 한천에 배양한 후 형성된 집락 중 무색 집락을 대상으로 E. coli로 동정된 것을 E. coli O157 라텍스 응집검사를 실시하여 응집이 되면 양성으로 판독하였다. 결 과 : 총 317 검체중 11월에 1 검체 (0.3%)에서 Shiga 독소를 생성하지 않는 E. coli O157:NM이 분리되었다. 7세 남아로 2일간의 복통과 1일간의 설사 및 구토를 주소로 입원 한 후 특별한 치료없이 2일후 증상이 호전되어 퇴원하였다. 결 론 : 검사된 모든 대변 검체중 한 검체 (0.3%)만이 E. coli O157이 분리되었으나 Shiga 독소를 생성하지 않는 군주였다. 따라서 이 세균의 분리를 위한 통상적인 변배양 검사는 아직 불필요한 것으로 사료되었다.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제15권1호
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• pp.29-37
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• 2012

Purpose: To examine the prevalence of $Clostridium$ $difficile$ ($C.$ $difficile$) colonization (CDC) and potential neonatal determinants of CDC in hospitalized preterm infants. Methods: Fecal samples were serially collected within 72 h after birth and at 1, 2, and 4-6 weeks of age from preterm infants in the neonatal intensive care units (NICUs) of two different university hospitals. Total bacterial DNA was extracted from each fecal sample from 49 infants, and polymerase chain reaction (PCR) was performed with primers for the 16S gene of $C.$ $difficile$ and the toxin A and toxin B genes. The correlation between the results of $C.$ $difficile$ PCR assays and the clinical characteristics of the infants was analyzed. Results: The prevalence rates of CDC were 34.7, 37.2, 41.3, and 53.1% within 72 h after birth and at 1, 2, and 4.6 weeks of age, respectively. The toxin positivity rate was significantly higher in the infants with persistent CDC than in those with transient CDC (8/12 [66.7%] vs. 6/25 [24.5%] ($p$=0.001). Among the various neonatal factors, only the feeding method during the first week after birth was significantly associated with persistent CDC. Exclusive breast-milk feeding (EBMF) significantly decreased the risk of persistent CDC compared to formula or mixed feeding (adjusted odds ratio: 0.133, 95% confidence interval: 0.02-0.898, $p$=0.038). Conclusion: The prevalence of CDC increased with the duration of hospitalization in preterm infants in the NICU. EBMF during the first week after birth in hospitalized preterm infants may protect against persistent CDC.

• 한국축산식품학회지
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• 제38권1호
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• pp.203-208
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• 2018

The objective of this study was to investigate the pathogenicity and antimicrobial resistance of foodborne pathogens isolated from farmstead cheeses. Twenty-seven isolates, including 18 Bacillus cereus, two Escherichia coli, and seven Staphylococcus aureus, were subjected to polymerase chain reaction (PCR) to detect virulence genes and toxin genes, and the antibiotic resistances of the isolates were determined. All E. coli isolates were determined by PCR to be non-pathogenic. Among the 18 B. cereus isolates, 17 isolates (94.4%) were diarrheal type, as indicated by the presence of nheA, entFM, hbIC, cytK and bceT genes, and one isolate (5.6%) was emetic type, based on the presence of the CER gene. Among the seven S. aureus isolates, three (42.9%) had the mecA gene, which is related to methicillin-resistance. Most B. cereus isolates (94.7%) showed antibiotic resistance to oxacillin and penicillin G, and some strains also showed resistance to ampicillin (26.3%), erythromycin (5.3%), tetracycline (10.5%), and vancomycin (5.3%). These results indicate that microbial food safety measures for farmstead cheese must be implemented in Korea because antibiotic resistant foodborne pathogens, with resistance even to vancomycin, harboring virulence genes were found to be present in the final products of farmstead cheese.

• Journal of Microbiology and Biotechnology
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• 제24권8호
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• pp.1051-1058
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• 2014

Platelet-activating factor receptor (PAFR) plays an important role in bacterial infection and inflammation. We examined the effect of the bacterial cell wall components lipopolysaccharide (LPS) and lipoteichoic acid (LTA) from Lactobacillus plantarum (pLTA) and Staphylococcus aureus (aLTA) on PAFR expression in THP-1, a monocyte-like cell line. LPS and aLTA, but not pLTA, significantly increased PAFR expression, whereas priming with pLTA inhibited LPS-mediated or aLTA-mediated PAFR expression. Expression of Toll-like receptor (TLR) 2 and 4, and CD14 increased with LPS and aLTA treatments, but was inhibited by pLTA pretreatment. Neutralizing antibodies against TLR2, TLR4, and CD14 showed that these receptors were important in LPS-mediated or aLTA-mediated PAFR expression. PAFR expression is mainly regulated by the nuclear factor kappa B signaling pathway. Blocking PAF binding to PAFR using a PAFR inhibitor indicated that LPS-mediated or aLTA-mediated PAF expression affected TNF-${\alpha}$ production. In the mouse small intestine, pLTA inhibited PAFR, TLR2, and TLR4 expression that was induced by heat-labile toxin. Our data suggested that pLTA has an anti-inflammatory effect by inhibiting the expression of PAFR that was induced by pathogenic ligands.

• Journal of Microbiology and Biotechnology
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• 제24권12호
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• pp.1609-1621
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• 2014

The plant pathogen Burkholderia gladioli, which has a broad host range that includes rice and onion, causes bacterial panicle blight and sheath rot. Based on the complete genome sequence of B. gladioli BSR3 isolated from infected rice sheaths, the genome of B. gladioli BSR3 contains the luxI/luxR family of genes. Members of this family encode N-acyl-homoserine lactone (AHL) quorum sensing (QS) signal synthase and the LuxR-family AHL signal receptor, which are similar to B. glumae BGR1. In B. glumae, QS has been shown to play pivotal roles in many bacterial behaviors. In this study, we compared the QS-dependent gene expression between B. gladioli BSR3 and a QS-defective B. gladioli BSR3 mutant in two different culture states (10 and 24 h after incubation, corresponding to an exponential phase and a stationary phase) using RNA sequencing (RNA-seq). RNA-seq analyses including gene ontology and pathway enrichment revealed that the B. gladioli BSR3 QS system regulates genes related to motility, toxin production, and oxalogenesis, which were previously reported in B. glumae. Moreover, the uncharacterized polyketide biosynthesis is activated by QS, which was not detected in B. glumae. Thus, we observed not only common QS-dependent genes between B. glumae BGR1 and B. gladioli BSR3, but also unique QS-dependent genes in B. gladioli BSR3.

• Journal of Microbiology and Biotechnology
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• 제33권3호
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• pp.329-338
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• 2023

Enterohemorrhagic Escherichia coli (EHEC) is a foodborne pathogen that produces attaching and effacing lesions on the large intestine and causes hemorrhagic colitis. It is primarily transmitted through the consumption of contaminated meat or fresh produce. Similar to other bacterial pathogens, antibiotic resistance is of concern for EHEC. Furthermore, since the production of Shiga toxin by this pathogen is enhanced after antibiotic treatment, alternative agents that control EHEC are necessary. This study aimed to discover alternative treatments that target virulence factors and reduce EHEC toxicity. The locus of enterocyte effacement (LEE) is essential for EHEC attachment to host cells and virulence, and most of the LEE genes are positively regulated by the transcriptional regulator, Ler. GrlA protein, a transcriptional activator of ler, is thus a potential target for virulence inhibitors of EHEC. To identify the GrlA inhibitors, an in vivo high-throughput screening (HTS) system consisting of a GrlA-expressing plasmid and a reporter plasmid was constructed. Since the reporter luminescence gene was fused to the ler promoter, the bioluminescence would decrease if inhibitors affected the GrlA. By screening 8,201 compounds from the Korea Chemical Bank, we identified a novel GrlA inhibitor named Grlactin [3-[(2,4-dichlorophenoxy)methyl]-4-(3-methylbut-2-en-1-yl)-4,5-dihydro-1,2,4-oxadiazol-5-one], which suppresses the expression of LEE genes. Grlactin significantly diminished the adhesion of EHEC strain EDL933 to human epithelial cells without inhibiting bacterial growth. These findings suggest that the developed screening system was effective at identifying GrlA inhibitors, and Grlactin has potential for use as a novel anti-adhesion agent for EHEC while reducing the incidence of resistance.

• Pediatric Infection and Vaccine
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• 제27권2호
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• pp.90-101
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• 2020

목적: 급성 위장염의 대부분의 경우 원인 병원체가 확인되지 않는다. 최근 들어 발달한 multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) 검사는 장염 병원체 검출에 도움을 줄 수 있다. 이 연구는 multiplex RT-PCR을 이용해, 소아 장염환자에서 병원체의 역학을 조사하고자 하였다. 방법: 2015년 5월부터 2018년 6월까지 대한민국 서울의 2차병원에서 급성 위장염으로 진단받은 소아 환자의 대변에서 병원체를 확인하기 위해 multiplex RT-PCR 검사를 시행하였다. 결과: 바이러스 병원체에 대한 1,366개의 대변 검체 중, 483개(35.3%)에서 1개 이상의 병원체가 분리되었다. A군 로타바이러스는 106건(7.8%)에서 확인되었으며, 양성률은 3.0% (8/263)에서 16.7% (48/288)까지 매년 증가했다(P<0.001). 노로바이러스 GII는 가장 흔한 바이러스성 병원체였고(263/1366, 19.3%), 3년간 양성률은 증가하지 않았다. 세균성 병원체에 대한 304개의 대변 검체 중 캄필로박터(32/304, 10.5%)는 가장 흔한 세균성 병원체였으며, 그 다음으로 Clostridium difficile (toxin B) (22/304, 7.2%), 살모넬라균(17/304, 5.6%)이었다. 이 균들의 양성률은 연구기간 동안 증가하지 않았다. 결론: 로타바이러스 백신 도입 이후 노로바이러스 GII가 소아 장염에서 주요한 병원체였지만, 연구기간 동안 로타바이러스 감염 환자가 증가했고, 특히 2018년에는 급증했다. 따라서 새로운 로타바이러스 균주의 등장 가능성을 포함한 추가 연구가 필요하다. 캄필로박터는 소아 세균성 장염의 주요 원인이며, 적절한 치료를 위해 이 균의 임상적 특성을 고려하고 지속적 감시가 필요하겠다.

• 한국수산과학회지
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• 제33권6호
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• pp.550-553
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• 2000

해수에서 분리한 마비성패류독 분해 균주 Enterobactersp. CW-6 균주의 마비성 패류독소 최적 분해 온도 및 시험 균주의 독소 분해과정 중의 독소 함량 및 구성성분을 조사한 결과는 다음과 같다. 시험 균주는 배양 적온으로 확인된 $30, 35^{\circ}C$에서 배양 5일만에 각각 최초 첨가 독력의 $56.8, 44.1{\%}$, 12일 후에는 $93.0, 79.5{\%}$를 분해하였다. 그러나, 배양 적온에서 벗어날수록 균주의 독소 분해 활성은 감소하여 $20^{\circ}C$에서는 배양 12일 후에도 최초 독력의 $69.0{\%}$가 잔존하였다. 시험 균주 Enterobacter sp. CW-6는 $30^{\circ}C$에서의 조독소를 이용한 분해 활성 측정에서 초기 농도 38.2nmole/g의 마비성패류독을 배양 8일 및 12일째 각각 $88.4, 92.7{\%}$ 분해하였다. 정제 독소를 이용한 분해 시험에서, 조독소 분해과정 중에 일시적으로 증가하는 STX group은 GTX2, 3에서 전환된 것으로 확인되었다. 시험 균주 Enterobactersp. CW-6는 정제 독소에 대해서도 강한 분해 활성을 나타내었으며, 최초 농도 47 nmole/g 의 GTX1과 37 nmole/g GTX4를 분해 과정 12일 후에 각각 $100, 90.8{\%}$ 분해하였으며, GTX2, 3 혼합물에 대하여는 최초농도 25.6 nmole/g의 독소를 12일 후에 $66.4{\%}$까지 분해하였다.

• 한국균학회소식:학술대회논문집
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• 한국균학회 2014년도 추계학술대회 및 정기총회
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• pp.13-13
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• 2014

Species belonging to the genus Fusarium are widely distributed and cause diseases in many plants. Isolation of fungal strains from air or cereals is necessary for disease forecasting, disease diagnosis, and population genetics [1]. Previously we showed that Fusarium species are resistant to toxoflavin produced by the bacterial rice pathogen Burkholderia glumae while other fungal genera are sensitive to the toxin, resulting in the development of a selective medium for Fusarium species using toxoflavin [2]. In this study, we have tried to elucidate the resistant mechanism of F. graminearum against toxoflavin and interaction between the two pathogens in nature. To test whether B. glumae affects the development of F. graminearum, the wild-type F. graminearum strains were incubated with either the bacterial strain or supernatant of the bacterial culture. Both conditions increased the conidial production five times more than when the fungus was incubated alone. While co-incubation resulted in dramatic increase of conidial production, conidia germination delayed by either the bacterial strain or supernatant. These results suggest that certain factors produced by B. glumae induce conidial production and delay conidial germination in F. graminearum. To identify genes related to toxoflavin resistance in F. graminearum, we screened the transcriptional factor mutant library previously generated in F. graminearum [3] and identified one mutant that is sensitive to toxoflavin. We analyzed transcriptomes of the wild-type strain and the mutant strain under either absence or presence of toxoflavin through RNAseq. Expression level of total genes of 13,820 was measured by reads per kilobase per million mapped reads (RPKM). Under the criteria with more than two-fold changes, 1,440 genes were upregulated and 1,267 genes were down-regulated in wild-type strain than mutant strain in response to toxoflavin treatment. A comparison of gene expression profiling between the wild type and mutant through gene ontology analysis showed that genes related to metabolic process and oxidation-reduction process were highly enriched in the mutant strain. The data analyses will focus on elucidating the resistance mechanism of F. graminearum against toxoflavin and the interaction between the two pathogens in rice. Further evolutionary history will be traced through figuring out the gene function in populations and in other filamentous fungi.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제1권1호
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• pp.138-143
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• 1998

저자들은 만성 설사 및 점액성 혈변을 주소로 내원한 25개월 남아에서 대장 내시경 및 조직생검, latex 응집 반응검사로 위막성 대장염 1례를 진단, 치료하였기에 보고하는 바이다.