• Journal of Microbiology and Biotechnology
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• 제32권5호
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• pp.602-611
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• 2022

The persistence of pathogenic Escherichia coli under acidic conditions poses a serious risk to food safety, especially in acidic foods such as kimchi. To identify the bacterial factors required for acid resistance, transcriptomic analysis was conducted on an acid-resistant enterotoxigenic E. coli strain and the genes with significant changes in their expression under acidic pH were selected as putative resistance factors against acid stress. These genes included those associated with a glutamate-dependent acid resistance (GDAR) system and copper resistance. E. coli strains lacking GadA, GadB, or YbaST, the components of the GDAR system, exhibited significantly attenuated growth and survival under acidic stress conditions. Accordantly, the inhibition of the GDAR system by 3-mercaptopropionic acid and aminooxyacetic acid abolished bacterial adaptation and survival under acidic conditions, indicating the indispensable role of a GDAR system in acid resistance. Intriguingly, the lack of cueR encoding a transcriptional regulator for copper resistance genes markedly impaired bacterial resistance to acid stress as well as copper. Conversely, the absence of YbaST severely compromised bacterial resistance against copper, suggesting an interplay between acid and copper resistance. These results suggest that a GDAR system can be a promising target for developing control measures to prevent E. coli resistance to acid and copper treatments.

• 한국식품위생안전성학회지
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• 제6권3호
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• pp.147-155
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• 1991

내열성장독소(ST)를 생산하는 병원성대장균(KS-4, KM-7, KM-12)을 설사돈으로부터 분리하고 몇가지 배양상 특성과 ST생산유전자의 성질을 조사하였다. 분리균은 succinate salts 배지의 pH가 8.5~9.0일 때 ST 생산량이 가장 많았으며, ST정제용 배지로는 succinate salts 배지가 가장 유리한 것으로 생각되어 진다. ST 생산, 축적은 분리균 모두 14~16 시간에서 가장 높았고 균체량은 배양 시작 후 20시간에 가장 많았다. ST 생산 능력이 가장 우수한 KM-7균주로 부터 ST생산 유전을 함유하는 약 80Kbp의 plasmid를 분리하고 EcoRI 제한효소를 절단한 16Kbp의 DNA절편을 pBR 322 vector DNA에 접합시킨 pKD 37 plasmid를 E. coli K-12에 형질전화시켜서 KM-7 보다 ST 생산능력이 우수한 균주(eKT 53)를 얻었다.

• 한국미생물·생명공학회지
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• 제13권3호
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• pp.203-207
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• 1985

장내세균 Bifidobacterium longum에 의한 대장균성 설사증의 주 원인균인 E. coli $A_2$의 생육저해를 혐기적 조건에서 조사한 결과를 요약하면 다음과 같다. 한국 성인으로부터 분리ㆍ동정한 Bif. longum SKD-2001은 E. coli $A_2$의 생육을 저해시키는 생육저해 작용을 가지고 있었다. Bifidus 균제제에서 분리ㆍ동정한 Bif. longum SKD-2004도 역시 E. coli $A_2$의 생육을 저해하였다. pH가 저하됨에 따라서 생육저해가 있는 것으로 보아 E. coli $A_2$의 생육저해는 Bif., longum이 생산한 lactic acid와 acetic acid에 의해 배양액의 pH가 저하됨으로써 나타나는 것으로 사료되었다.

• 한국수산과학회지
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• 제49권6호
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• pp.800-806
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• 2016

In total, 151 Escherichia coli isolates from Ruditapes philippinarum in Gomso Bay were analyzed for their susceptibility to 18 different antimicrobial agents and for genes associated with virulence. For virulence genes, each strain of the isolates was positive for the enterotoxigenic E. coli (ETEC)-specific heat-stable toxin (estA), enteroinvasive E. coli (EIEC)-specific invasion-associated locus (iaa) gene and enteropathogenic E. coli (EPEC)-specific attaching and effacing (eae) gene. According to a disk diffusion susceptibility test, resistance to ampicillin was most prevalent (23.2%), followed by resistance to amoxicillin (22.5%), ticarcillin (20.5%), tetracycline (18.5%), nalidixic acid (12.6%), ciprofloxacin (10.6%), streptomycin (9.9%), and chloramphenicol (6.6%). More than 35.8% of the isolates were resistant to at least one antimicrobial agent, and 19.9% were resistant to four or more classes of antimicrobials; these were consequently defined as multidrug resistant. Minimum inhibitory concentration (MIC) ranges for the antimicrobial resistance of the 15 different antimicrobial agents of 54 E. coli strains were confirmed by varying the concentrations from $32-2,048{\mu}g/mL$. Overall, these results not only provide novel insights into the necessity for seawater and R. philippinarum sanitation in Gomso Bay but they also help to reduce the risk of contamination by antimicrobial-resistant bacteria.

• 한국동물위생학회지
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• 제21권4호
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• pp.413-429
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• 1998

Escherichia coli is recovered from a wide variety of infections in many animals species. It may be a primary or secondary agent. Nursing and young animals are particularly susceptible, and urinary tract infections are frequent. The various serotypes of E coli are intestinal inhabitants of animals including humans and probably infect most mammals and birds : therefore, they have a cosmopolitan distribution. Colibacillosis refers to any totalized or systemic infection caused entirely or partly by E coli. Collibacillosis in mammals is most often a primary enteric disease, whereas collibacillosis in poultry is typically a secondary located or systemic disease occurring when host defenses have been impaired or overwhelmed. Other opportunistic bacteria, which can be identified by culture, may play a similar role to that of I coli in secondary infections. Collectively, infections caused by E coli are responsible for significant economic losses to the animal performance. From the standpoint of pathogenic mechanisms and diseases, four major categories of E coli are recognized : enterotoxigenic(ETEC), enteropathogenic (EPEC), enteroinvasive(EIEC), and enterohemorrhagic(EHEC). In addition, two less-well-defined E coli categories are recognized in animals and humans : enteroaggregative and cytotoxin necrotizing factor-positive. The aforementioned categories are represented by different serotypes. Certain serotypes show a host preference and are encountered more frequently in some disease syndromes. Of the four major categories, ETEC is the most common cause of diarrhea in calves, lambs, and pigs. Strains in the other categories cause the less-common diarrhea and other disease syndromes. Enterotoxins and pilus antigens are the two most prominent virulence factors thus far identified for ETEC. Two enterotoxins, one heat-stable(ST) and one heat-labile(LT), are produced by enterotoxigenic strains of E coli : not all culture produce both of these plasmid-based enterotoxins.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• 제25권1호
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• pp.79-86
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• 2022

Purpose: To determine the effect of zinc deficiency on fecal protein, electrolyte, and short-chain fatty acid levels in both heat-stable (ST) and heat-labile (LT) enterotoxigenic Escherichia coli (ETEC)-induced diarrhea in rats. Methods: Albino rats, weighing 100 to 150 g, were divided into 2 groups, with 15 animals each: non-zinc and zinc-deficient. These two groups were sub-divided into three sub-groups with five rats each: control (saline); LT-ETEC; and ST-ETEC. Sodium phytate (30 mmol/L) was added to the animals' water to induce zinc deficiency, while diarrhea was induced using 5×10⁹ ETEC cells/mL. Fecal protein levels were estimated using the Bradford method, while sodium and potassium levels were determined using atomic absorption spectrophotometry. Short-chain fatty acids were measured using gas chromatography-mass spectrometry. Results: Among the non-zinc and zinc-deficient groups, there were significant increases (p=0.04), (p=0.03) in fecal protein concentrations (mg/mL) in the LT-ETEC- (4.50±0.33), (6.50±0.26) and ST-ETEC- (3.85±0.19), (5.98±0.32) induced groups compared to the control groups (2.60±0.52), (3.50±0.11) respectively. Fecal sodium and potassium levels (mg/L) were significantly (p=0.029) increased in non-zinc-deficient rats induced with LT-ETEC (9.35±0.95, 1.05±0.48), and ST-ETEC (9.96±1.02, 1.21±0.45) compared with the control group (8.07±0.44, 0.47±0.17) but the increase were not statistically significant (p=0.059) in the zinc deficient rat groups. Fecal acetate and propionate levels (mg/g) significantly (p=0.032) increased when induced with LT-ETEC and ST-ETEC in non-zinc and zinc-deficient groups compared with the control groups. Conclusion: Zinc deficiency among rats with ETEC-induced diarrhea elevated fecal protein loss but may not have an effect on fecal sodium, potassium and short-chain fatty acid levels.

• 한국축산식품학회:학술대회논문집
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• 한국축산식품학회 2003년도 제31차 춘계 학술대회
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• pp.15-23
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• 2003

식품으로 인한 질병은 개인의 생명을 위협할 뿐 아니라 건전한 노동력의 상실로 생산성을 감소시키고 의료비를 증가시켜 개인의 행복 및 국가 경제에 부담을 준다 (Buzby et al. 1996, Mead et at. 2000). HACCP와 여러 식품안전에 관한 규제의 시행 등의 많은 노력에도 불구하고 Salmonella serotypes, Staphylococcus aureus, Camplobacter jejuni, Campylobacter coli, enterotoxigenic and enteroinvasive Escherichia coli, Clostridium perfringens, Bacillus cereus와 같은 식품기원 병원성 세균으로 인한 질병은 줄어들고 있지 않다. 오히려 외식 위주로 변해가는 생활습관은 식품을 통한 이들 병원성 세균의 전파가능성을 증가시키고 있다. 게다가 새로운 병원성균 (Yersinia enterocolitica, Listeria monocytogenes, E. coli 0157:H7, Aeromonas spp., Plesiomonas spp.) 의 출현 또는 특정 식품과 연관되어 나타나는 특정 subtype (Salmonella serotype Enteritidis) 의 출현은 이제까지 통용되어왔던 식품기원 세균을 위한 제어프로그램과는 다른 각도로 재원을 활용해야 할 동기를 부여하고 있다.

• 대한수의학회지
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• 제38권4호
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• pp.837-842
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• 1998

The present study describes the effectiveness of egg yolk antibodies (IgY) against enteric colibacillosis and edema disease in piglets. The antibodies were gained from the egg yolk of hens immunized with k88, k99, 987p fimbrial adhesin and heat-labile toxin antigens of enterotoxigenic Escherichia coli (ETEC). Orally-administered egg yolk antibodies solution protected against experimental challenge with ETEC $K88^+$ and $k99^+$ strains in neonatal piglets and mice. In field trial, a total of 598 diarrheal piglets were orally treated with 3ml of antibody once a day to determine for the therapeutic effect. Of them, 582 (97.3%) piglets were recovered from diarrhea in 3 days. We also experimentally treated with the egg yolk antibodies twice a day for 5 consecutive days for 94 weaning piglets with edema disease for the determination of therapeutic effects. Seventy four piglets (78.7%) were recovered from clinical edema signs. Theses findings indicate that egg yolk antibodies against k88, k99, 987p and LT of ETEC are useful source of passive immunity for enteric colibacillosis and edema disease of piglets.

• 대한수의학회지
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• 제51권2호
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• pp.151-158
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• 2011

The study evaluated whether a transgenic carrot vaccine could induce a K88-specific immune response in sows and whether the resultant maternal antibody could protect piglets against enterotoxigenic Escherichia coli (ETEC) K88ac infection. Sows (n = 15) selected randomly from a farm in Korea were assigned to three groups (n = 5 per group: control [untreated]), group A (orally inoculated with a nontransgenic and transgenic carrot vaccines at 2 and 4 weeks ante partum, respectively), and group B (conventionally vaccinated according to the manufacturer's instructions). After 7 days of lactation, 5 piglets selected randomly from each group were challenged with $1{\times}10^{10}$ colony forming units/mL ETEC K88ac. Group C had the lowest mean fecal consistency score on post-challenge days 1 and 7. Histiologically, On post-challenge day 7, group C showed an increased duodenum and ileum villus:crypt ratio, compared to group A in the duodenum, with group B displaying the highest ratio. Groups B and C had more increased villus width than group A in the jejunum. Group C displayed the greatest increase in villus width in the ileum. The colostrums and serum from groups B and C displayed higher concentrations of IgA and IgG against ETEC K88, compared to group A. Based on the results, it was concluded that the transgenic carrot vaccine in sow per oral may have an effect on preventing piglet diarrhea as good as commercial recombinant vaccine.

• 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.