• 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.

• Food Science and Biotechnology
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• 제18권2호
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• pp.343-349
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• 2009

Inhibitory effect of Escherichia coli O157 adhered to Caco-2 cells by the cells of Lactobacillus plantarum K11 and the cell-free culture supernatant (CFCS) and bacteriocin prepared from this strain was investigated. As the cell counts of viable L. plantarum K11 previously adhered to Caco-2 were increased, the rate of adhesion and adherent cell counts of E. coli O157 was lower. However, because the heated L. plantarum K11 rarely have the adhesion ability to Caco-2, the adhesion rate and adherent cell counts of E. coli O157 were high. In addition, the inhibitory effects of E. coli O157 adhesion by the CFCS and bacteriocin of L. plantarum K11 were dose-dependent manner. Therefore, the inhibition of adhesion of E. coli O157 to Caco-2 may result from the antimicrobial substances such as lactic acid and bacteriocin. Moreover the inhibitory activity of adhesion by the heated bacteriocin for 30 min at 100oC was similar to activity of non-treated bacteriocin, but the activity was disappeared by treatment with protease.

• 대한미생물학회지
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• 제22권2호
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• pp.155-162
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• 1987

To determine the prevalence of antibiotic resistance in fecal E. coli and to investigate possible associations between antibiotic resistance and other plasmid-mediated virulence properties, antibiotic disk susceptibility tests for nine antibiotics were done on 141 strains of E. coli isolated from diarrheal children and well controls. Eighty two percent of the test strains were resistant to one or more antibiotics. Antibiotics to which the test strains were most resistant in descending order were ampicillin (85%), trimethoprim/sulfamethoxazol (60%), and cephalothin (55%). Seventy nine percent of these resistant strains were resistant to two or more antibiotics. All 141 test strains were sorted into enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enteroadherent E. coli (EAEC) and non-pathogenic E. coli and the percentages of strains resistant to multiple antibiotics were compared. Among ETEC regardless of its source, multiple drug resistance was more frequent in strains producing heatstable enterotoxin (ST) only than in strains producing only heat-labile enterotoxin (LT) or both. In EAEC, multiple resistance was more frequently associated with strains isolated from diarrheal patients than with those from well controls. The major antibiotic resistance patterns possessed by multiple resistant enteropathogenic strains were $SXT^R$ $AM^R$, $CR^R$, and $SXT^R$ $AM^R$ $CR^R$. Of 28 ST- producing $SXT^R$ ETEC, 26(96%) were also resistant to ampicillin and 17 (61%) were resistant to cephalothin. The similar pattern was observed in EAEC and EPEC as well. This study has important implications for the treatment of E. coli diarrhea with antibiotics because it is possible that dissemination of virulence could occur under the force of selective antibiotic pressure. In addition, this study suggests that the in vivo efficacy of SXT in treating diarrheal illness be reevaluated.

• 대한수의학회지
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• 제25권1호
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• pp.61-67
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• 1985

One hundred and twenty seven strains of Gram-negative rods (72 E. coli, 45 Klebsieila pneumoniae, 8 Enterobacter spp. and 2 Pseudomonas aeruginosa) isolated from bovine mastitis were examined for resistance to ampicilin, carbenicillin and cefazolin, ${\beta}$-lactamase activity and transferable ${\beta}$-lactamase plasmids. Stains resistant to ampicillin were 13.9% in E. coli, 93.3% in Klebsiella pneumoniae, 87.5% in Enterobacter. spp. and all in Pseudomonas aeruginosa, Resistance of E. coli, Klebsiella pneumoniae and Enterobacter spp. to ampicillin was due to the ${\beta}$-lactamases, but all Pseudomonas aeruginosa exhibited a high level of the non-enzymic resistance. Transferable plasmid-mediated ${\beta}$-lactamase synthesis was demonstrated in 61.9% of Klebsiella pneumoniae, 50% of E. coli and 42.9% of Enterobacter spp. The same ${\beta}$-lactamase plasmids specified different resistance levels to various ${\beta}$-lactam antibiotics in different recipients.

• Clinical and Experimental Pediatrics
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• 제60권7호
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• pp.221-226
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• 2017

Purpose: Escherichia coli sequence type (ST) 131, a multidrug-resistant clone causing extraintestinal infections, has rapidly become prevalent worldwide. However, the epidemiological and clinical features of pediatric infections are poorly understood. We aimed to explore the characteristics of ST131 Escherichia coli isolated from Korean children with urinary tract infections. Methods: We examined 114 uropathogenic E. coli (UPEC) isolates from children hospitalized at Chung-Ang University Hospital between 2011 and 2014. Bacterial strains were classified into STs by partial sequencing of seven housekeeping genes (adk, fumC, gyrB, icd, mdh, purA, and recA). Clinical characteristics and antimicrobial susceptibility were compared between ST131 and non-ST131 UPEC isolates. Results: Sixteen UPEC isolates (14.0%) were extended-spectrum ${\beta}-lactamase$ (ESBL)-producers; 50.0% of ESBL-producers were ST131 isolates. Of all the isolates tested, 13.2% (15 of 114) were classified as ST131. There were no statistically significant associations between ST131 and age, sex, or clinical characteristics, including fever, white blood cell counts in urine and serum, C-reactive protein, radiologic abnormalities, and clinical outcome. However, ST131 isolates showed significantly lower rates of susceptibility to cefazolin (26.7%), cefotaxime (40.0%), cefepime (40.0%), and ciprofloxacin (53.3%) than non-ST131 isolates (65.7%, 91.9%, 92.9%, and 87.9%, respectively; P<0.001 for all). ESBL was more frequently produced in ST131 (53.3%) than in non-ST131 (8.1%) isolates (P<0.01). Conclusion: ST131 E. coli isolates were prevalent uropathogens in children at a single medical center in Korea between 2011 and 2014. Although ST131 isolates showed higher rates of antimicrobial resistance, clinical presentation and outcomes of patients were similar to those of patients infected with non-ST131 isolates.

• Journal of Microbiology and Biotechnology
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• 제30권10호
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• pp.1552-1558
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• 2020

With an increase in the consumption of non-heated fresh food, foodborne shiga toxin-producing Escherichia coli (STEC) has emerged as one of the most problematic pathogens worldwide. Endolysin, a bacteriophage-derived lysis protein, is able to lyse the target bacteria without any special resistance, and thus has been garnering interest as a powerful antimicrobial agent. In this study, rV5-like phage endolysin targeting E. coli O157:H7, named as LysECP26, was identified and purified. This endolysin had a lysozyme-like catalytic domain, but differed markedly from the sequence of lambda phage endolysin. LysECP26 exhibited strong activity with a broad lytic spectrum against various gram-negative strains (29/29) and was relatively stable at a broad temperature range (4℃-55℃). The optimum temperature and pH ranges of LysECP26 were identified at 37℃-42℃ and pH 7-8, respectively. NaCl supplementation did not affect the lytic activity. Although LysECP26 was limited in that it could not pass the outer membrane, E. coli O157: H7 could be effectively controlled by adding ethylenediaminetetraacetic acid (EDTA) and citric acid (1.44 and 1.14 log CFU/ml) within 30 min. Therefore, LysECP26 may serve as an effective biocontrol agent for gram-negative pathogens, including E. coli O157:H7.

• 한국식품위생안전성학회지
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• 제32권3호
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• pp.222-227
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• 2017

연구는 대기압 유전체장벽방전 플라즈마 처리에 따른 식품유해 미생물 사멸효과를 조사하기 위해 수행되었다. 플라즈마 처리 시, 활성종 생성 및 농도에 영향을 미치는 노출시간, 노출거리, 산소비율, 전력 변화에 따른 E. coli의 사멸효과를 조사한 결과, E. coli의 사멸율은 플라즈마 처리를 위한 노출시간, 산소비율, 전력의 증가에 따라 증가한 반면, 노출거리의 증가에 따라서는 사멸율이 감소하였다. 이 결과는 미생물 시료가 플라즈마에 노출되는 시간이 증가됨으로서 시료 내 NO 농도가 증가되고, E. coli의 사멸율 역시 증가되는 결과로 뒷받침할 수 있고, 미생물 사멸효과를 높이기 위해서는 활성종의 농도가 증가되어야 함을 의미한다. E. coli와 함께 B. cereus, B. subtilis, B. thuringiensis, B. atrophaeus를 대상으로 대기압 유전체 장벽방전 플라즈마에 의한 살균효과를 조사한 결과, 72.3~91.3%의 높은 사멸율을 나타내었다. 이러한 결과로 미루어, 대기압 유전체장벽방전 플라즈마기술은 다양한 미생물에 적용될 수 있는 유용한 살균기술임을 확인하였다.

• KSBB Journal
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• 제13권2호
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• pp.168-173
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• 1998

Gamma irradiated and non-irradiated Agrimonia pilosa Ledebour were extracted by 70% ethanol. The combined effects of the Agrimonia pilosa Ledebour extract and NaCl on survival of Escherichia coli O157:H7 in tryptic soy broth were investigated. E. coli O157:H7 decreased ca 1 log cycle by the addition of 2% sample extract, and the anthbacterial activity was increased as the concentration of sample extract was increased. The irradiation effect of the sample on antibacterial activity was not observed. On the treatment of NaCl alone, E. coli O157:H7 was inactivated (ca 3~4 log cycle reduction within 48 hr) in more than 7% NaCl. The higher inactivation(ca 5 log cycle reduction within 48 hr) occurred in the presence of 2% sample extract and 5% NaCl than in the addition of each alone. The extracted antibacterial substance was stable in the pH range of 4.0 to 7.0, heat treatment at 121$^\circ C$ for 15 min, and freezing at -18$^\circ C$ and thawing at 37$^\circ C$. There fore, the sample extract, would substantially increase the food-safety in terms of E. coli O157:H7.

• 한국식품과학회지
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• 제47권4호
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• pp.446-451
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• 2015

본 연구는 건강한 식이에 대한 관심이 늘어나면서 그 수요량이 증가하고 있는 녹즙에 대한 미생물학적 품질평가를 목적으로 실시되었다. 또한 날것으로 섭취하는 과채류의 장출혈성 대장균의 오염으로 인한 집단식중독 사고가 많이 보고되고 있는 상황에서 E. coli O157:H7이 녹즙에 오염되었을 경우 보관온도, 보관 시간별 미생물 커뮤니티의 변화를 정량 분석법과 DGGE분석을 통해 확인하여 잠재적인 식중독 위험성을 확인해 보고자 하였다. 정량 분석 결과 초기부터 총 호기성 세균수가 식품위생법상 기준치($1.0{\times}10^5CFU/mL$)를 초과한 결과를 보였으며, E. coli O157:H7에 대한 세균수 측정결과를 보면 $5^{\circ}C$와 $10^{\circ}C$에서 균수가 감소하다가 증가하는 경향을 보였다. DGGE결과를 보면 보관시간이 길고 보관온도가 높을수록 더 많은 미생물 분포도를 보였고, 저장시간이 후반으로 갈수록 부패균인 젖산균이 다수 출현하는 것을 확인할 수 있었다. 이 외에 Rahnella aquatilis와 Citrobacter, Pseudomonas 등의 기회감염성 세균이 검출되었다. 이에, 위 녹즙시료는 잠재적인 식중독의 위험성을 보이므로 제품의 생산, 유통에 더욱 주의를 기울일 필요가 있다고 생각된다. 또한, 제품 구입 후 냉장저장을 하더라도 가능한 한 빠른 섭취가 권장되는 바이다. E. coli O157:H7에 위 제품이 오염되었을 경우 냉장과 실온조건 모두에서 세균수가 증가하였고, 특히 실온에 방치하였을 경우 그 증가폭이 크므로, 이에 특히 주의를 기울일 필요가 있다고 생각된다.

• 한국미생물생명공학회:학술대회논문집
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• 한국미생물생명공학회 2000년도 Proceedings of 2000 KSAM International Symposium and Spring Meeting
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• pp.68-75
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• 2000

D-Tagatose is a potential bulking agent in food as a non-calorific sweetener. To produce D-tagatose from cheaper resources, plasmids harboring the L-arabinose isomerase gene (araA) from Escherichia coli was constructed because L-arabinose isomerase was previously suggested as an enzyme that mediates the bioconversion of galactose to tagatose as well as that of arabinose to ribulose. In the cultures of recombinant E.coli with pTC101, which harboring araA of E.coli, tagatose was produced from galactose in 9.9 % yield. The enzyme extract of E.coli containing pTC101 also converted galactose into tagatose in 96.4 % yield. For the economic production of D-tagatose, an L-arabinose isomerase of E.coli was immobilized using covalent binding on agarose. While the free L-arabinose isomerase produced tagatose with the rate of 0.48 mg/U$.$day, the immobilized one stably converted galactose into average 7.5 g/l$.$day of tagatose during 7 days with higher productivity of 0.87 mg/U$.$day. In the scaled up immobilized enzyme system, 99.9 g/l of tagatose was produced from galactose with 20 % equilibrium in 48 hrs. The process was stably repeated additional 2 times with tagatose production of 104.1 and 103.5 g/l.