• Title, Summary, Keyword: E. coli

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Growth Inhibition of Enteropathogenic Escherichia coli $A_2$and Escherichia coli $G_7$ by the Organic Acid Producing Bacteria (유기산 생성균에 의한 병원성 Escherichia Coli $A_2$와 Escherichia Coli $G_7$의 생육억제)

  • 백영진;배형석
    • Microbiology and Biotechnology Letters
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    • v.16 no.2
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    • pp.111-118
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    • 1988
  • The growth inhibition of enteropathogenic Escheriohia coli $A_2$and Escherichia coli G$_7$, causing the diarrhea in piglets, by the organic acid producing bacteria was studied in vitro. The metabolites of the organic acid bacteria, such as lactic acid, acetic acid inhibited the growth of E. coli $A_2$and E. coli G$_7$ in BL medium. The more the organic acid producing bacteria have ability to produce the organic acids, the higher these bacteria excelled the inhibitory efficacy against enteropathogenic E. coli. Among the strains examined, Lactobacillus casei Y and Streptococcus faecium C showed relatively strong growth inhibition against enteropathogenic E. coli.. When the organic acid producing bacteria and the enteropathogenic E. coli were incubated simultaneously in BL medium, bacteriostasis of E. coli was observed when the pH of BL culture was lowered to 5.0, and bacteriocidal effect was observed when the pH became Bess than 4.5, E. coli. $A_2$was more resistant to the organic acid bacteria than E. coli G$_7$.

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Clinical Characteristics and Antibiotic Resistance of Urinary Tract Infections in Children: Escherichia. coli Versus Non-E. coli (소아 요로감염의 원인균주별 임상양상과 항생제 내성률 : 대장균과 비대장균의 비교)

  • Bae, E-Young;Lee, Soo-Young;Jeong, Dae-Chul;Kang, Jin Han
    • Pediatric Infection and Vaccine
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    • v.17 no.2
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    • pp.67-73
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    • 2010
  • Purpose : We aimed to compare the clinical features and antibiotic resistance of urinary tract infection (UTI) caused by pathogens other than E. coli (non-E. coli) with UTI caused by E. coli in children. Methods : We enrolled patients with culture-proven UTI, who were admitted to the study hospital from September 2008 to August 2009. We investigated clinical data of patients with UTI and antibiotic resistance of isolated strains. For comparison, patients were divided according by results of the urine culture into E. coli and non-E. coli UTI groups. Results : A total of 84 patients participated in this study. Twenty one cases (25.0%) were caused by non-E. coli pathogens. Frequency of non-E. coli UTI differed according to age and sex: 'male <6 months', 10.5%; 'male ${\geq}$6 months', 50.0%; 'female <6 months', 43.7%; and 'female ${\geq}$6 months', 25.0% (P=0.014). More patients who received previous antibiotic treatment (P=0.017), but fewer patients who showed hematuria (P=0.014) were included in the non-E. coli UTI group than in the E. coli UTI group. Comparison of antibiotic resistance showed that the non-E. coli UTI group possessed more strains that were resistant to cefazolin, cefotaxime, imipenem, trimethoprim/sulfamethoxazole (TMP/SMZ) and tetracycline than the E. coli UTI group (P<0.05). Conclusion : Increased incidence, different distribution by age and sex, and high antibiotic resistance of non-E. coli UTI should be considered in selection of empirical antibiotics for treatment of UTI in children.

Construction Various Recombiant Plasmids for the Enhancement of Glutathione Production in E. coli. (E. coli에서 글루타치온 생산 증가를 위한 재조합 플라스미드의 구성)

  • 남용석;이세영
    • Journal of Life Science
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    • v.7 no.4
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    • pp.253-261
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    • 1997
  • In order to enhance glutathione production, various recombinant plasmids containing gshI and/or gshII genes isolated from E. coli K-12 were constructed and introduced into E. coli. Some plasmids contained one to three copies of gshI genes in pBR325 and others contained both gshI and genes for glutathione biosynthesis. $\gamma$-Glutamylcysteine synthetase activities of E, coli strains amplified tandem repeated gshI genes were dependent on the number of inserted gshI genes. The glutathione productivity of E. coli strains harboring various plasmids was investigated using an E. coli acetate kinase reaction as an ATP regenerating system. The glutathione productivity of E. coli strains harboring tandem repeated gshI genes was increased in proportion to the number of inserted gshI genes. By the introduction of gshII gene, the glutathione productivity of the E. coli was increased by two-fold compared with E. coli strain amplified gshI gene only. The enzymatic production of glytathione in E. coli was mainly affected by the increase of $\gamma$-glutamylcysteine synthetase activity. The highest glutathione productivity was obtained in E. coli strains harboring pGH-501 plasmid containing two copies of gshI and copy of gshII genes in pUC8 vector.

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Interaction of Escherichia coli K1 and K5 with Acanthamoeba casfellanii Trophozoites and Cysts

  • Matin, Abdul;Jung, Suk-Yul
    • The Korean Journal of Parasitology
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    • v.49 no.4
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    • pp.349-356
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    • 2011
  • The existence of symbiotic relationships between Acanthamoeba and a variety of bacteria is well-documented. However, the ability of Acanthamoeba interacting with host bacterial pathogens has gained particular attention. Here, to understand the interactions of Escherichia coli K1 and E. coli K5 strains with Acanthamoeba castellanii trophozoites and cysts, association assay, invasion assay, survival assay, and the measurement of bacterial numbers from cysts were performed, and nonpathogenic E. coli K12 was also applied. The association ratio of E. coli K1 with A. castellanii was 4.3 cfu per amoeba for 1 hr but E. coli K5 with A. castellanii was 1 cfu per amoeba for 1 hr. By invasion and survival assays, E. coli K5 was recovered less than E. coli K1 but still alive inside A. castellanii. E. coli K1 and K5 survived and multiplied intracellularly in A. castellanii. The survival assay was performed under a favourable condition for 22 hr and 43 hr with the encystment of A. castellanii. Under the favourable condition for the transformation of trophozoites into cysts, E. coli K5 multiplied significantly. Moreover, the pathogenic potential of E. coli K1 from A. castellanii cysts exhibited no changes as compared with E. coli K1 from A. castellanii trophozoites. E. coli K5 was multiplied in A. castellanii trophozoites and survived in A. castellanii cysts. Therefore, this study suggests that E. coli K5 can use A. castellanii as a reservoir host or a vector for the bacterial transmission.

Isolation of Verocytotoxin Producing Escherichia coli O157:H7 Due to Fcal Contamination on Carcass Surfaces (도체표면의 분변오염과 Verotoxin 생성 Escherichia coli O157:H7 분리에 관한 연구)

  • 홍종해;고주언
    • Journal of Food Hygiene and Safety
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    • v.12 no.1
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    • pp.78-82
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    • 1997
  • Surface swab samples from beef (188), pork (240) and chicken (95) carcasses were collected from slaughterhouse in Kangwon and Kyunggi areas from March through July 1996. The samples were examined on the level of E. coli biotype I relevant to fecal contamination due to unsanitary processing control and the existence of verocytotoxin-producing E. coli (VTEC). E. coli biotype I were confirmed from 38.8% of beef, 40.0% of pork, and 69.5% of chicken carcasses. Little variation was noted among three sampling points; rump, flank and neck of beef, ham, belly and jowls of pork. coli O157:H7 was only confirmed from 2 of 188 beef carcasses. E. coli biotype I. All the isolated E. coli O157 showed positive for vero cell cytotoxicity test. Isolation rate of E. coli O157 in summer was higher than in spring. In case of pork and chicken carcasses, E. coli O157 was isolated in summer only.

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Mutagenic Mechanism of Chloropropanols in Escherichia coli (대장균 변이주를 이용한 Chloropropanol 변이원성 기구의 해석)

  • Song, Geun-Seoup;Han, Sang-Bae;Choi, Dong-Seong
    • Korean Journal of Food Science and Technology
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    • v.31 no.1
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    • pp.246-251
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    • 1999
  • This study was designed to evaluate the mutagenicity and the primary mutagenic mechanism of chloropropanols by using various genotypes of E. coli WP2, E. coli TK and E. coli GW series strains. Chloropropanols showed the low mutagenic activities in E. coli WP2s and WP2 establishing the following order; 2,3-DCP> 3-MCPD>1,3-DCP. As compared with E. coli WP2s, the decrease of mutagenic activity and the increase of survival rate in E. coli WP2 $(WP2s\;uvrA^+)$ suggest that DNA lesions produced by chloropropanols could be easily removed by excision-repair system. From the diminution of mutagenic activity and survival rate in E. coli CM611 (WP2s lexA), it was confirmed that the mutagenesis by chloropropanols was dependent on the SOS-repair system. This fact could be also confirmed from the result that both the mutagenic activity and survival rate in E. coli TK610 (umuC) were much lower than those in E. coli TK603 $(umuC^+)$. In the experiment to examine the possibility that chloropropanols might have effects on the LexA of SOS response negative regulator, there was no variation in ${\beta}-galactosidase$ activities of E. coli GW1105 $[lexA3\;(Ind^-)]$ and GW1107 [lexA51 (Def)] by addition of the compounds, indicating that chloropropanols do not have any effects on the LexA, itself.

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Comparison of Upgraded Methods for Detecting Pathogenic Escherichia coli in Foods Using Centrifugation or Filtration

  • Choi, Yukyung;Lee, Heeyoung;Lee, Soomin;Kim, Sejeong;Lee, Jeeyeon;Ha, Jimyeong;Oh, Hyemin;Yoon, Yohan
    • Food Science of Animal Resources
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    • v.37 no.6
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    • pp.799-803
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    • 2017
  • In the present study, centrifugation and filtration pretreatments were evaluated to decrease sample preparation time and to improve the sensitivity and specificity of multiplex polymerase chain reaction (PCR) for the detection of low levels of pathogenic Escherichia coli in various foods. Pathogenic E. coli (E. coli NCCP11142, E. coli NCCP14037, E. coli NCCP 14038, E. coli NCCP14039, and E. coli NCCP15661) was inoculated into pork, beef, and baby leafy vegetables at 1, 2, and 3 Log CFU/g. The samples were shaken 30 times (control), then centrifuged or filtered. DNA extracts from the samples were subjected to PCR using the $Powerchek^{TM}$ Diarrheal E. coli 8-plex Detection Kit. In the pork samples, no E. coli was detected in the control samples, while E. coli were detected in 100% of 3-Log CFU/g inoculated and centrifuged samples, and in 100% of 2 and 3-Log CFU/g inoculated, and filtered samples. In the beef samples, all control samples appeared to be E. coli-negative, while E. coli was detected in 50-75% of centrifuged samples, regardless of inoculated level, and in 100% of 2 and 3-Log CFU/g inoculated, and filtered samples. In baby leafy vegetables, E. coli were not detected in 25-50% of the control samples, while E. coli were detected in 0-25% of the centrifuged samples, and 75-100% of the filtered samples, depending on the inoculum amount. In conclusion, filtration pretreatment can be used to minimize sample preparation time, and improve the sensitivity and specificity of rapid detection of pathogenic E. coli in various foods.

Phloretin Protects Macrophages from E. coli-Induced Inflammation through the TLR4 Signaling Pathway

  • Chauhan, Anil Kumar;Jang, Mihee;Kim, Yangmee
    • Journal of Microbiology and Biotechnology
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    • v.30 no.3
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    • pp.333-340
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    • 2020
  • Macrophages are the cells of the first-line defense system, which protect the body from foreign invaders such as bacteria. However, Gram-negative bacteria have always been the major challenge for macrophages due to the presence of lipopolysaccharides on their outer cell membrane. In the present study, we evaluated the effect of phloretin, a flavonoid commonly found in apple, on the protection of macrophages from Escherichia coli infection. RAW 264.7 cells infected with standard E. coli, or virulent E. coli K1 strain were treated with phloretin in a dose-dependent manner to examine its efficacy in protection of macrophages. Our results revealed that phloretin treatment reduced the production of nitric oxide (NO) and generation of reactive oxygen species along with reducing the secretion of proinflammatory cytokines induced by the E. coli and E. coli K1 strains in a concentration-dependent manner. Additionally, treatment of phloretin downregulated the expression of E. coli-induced major inflammatory markers i.e. cyclooxygenase-2 (COX-2) and hemeoxygenase-1 (HO-1), in a concentration dependent manner. Moreover, the TLR4-mediated NF-κB pathway was activated in E. coli-infected macrophages but was potentially downregulated by phloretin at the transcriptional and translational levels. Collectively, our data suggest that phloretin treatment protects macrophages from infection of virulent E. coli K1 strain by downregulating the TLR4-mediated signaling pathway and inhibiting NO and cytokine production, eventually protecting macrophages from E. coli-induced inflammation.

Isolation of bacteriophages having depolymerase and control of pathogenic E. coli O103 in biofilm on lettuce

  • Park, Dasom;Park, Jong-Hyun
    • Korean Journal of Food Science and Technology
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    • v.51 no.6
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    • pp.604-609
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    • 2019
  • To control pathogenic E. coli in biofilm, bacteriophages were isolated from environmental samples. Seventeen isolates had depolymerase activities by translucent zones at the rims of plaques. To determine biofilm-forming ability, an abiotic plastic surface of polystyrene was used; E. coli O103 showed the highest biofilm formation at 30℃ after 24 h. Moreover, biofilm by E. coli O103 on the biotic surface of lettuce was observed by a scanning electron microscope. The bacteriophage cocktail of ΦNOECP40 and ΦNOECP44 showing depolymerase activities was prepared to eliminate the E. coli inbiofilm. By organic acids, reduction of E. coli in biofilm was insignificant and almost undetectable. However, the abundance of E. coli in biofilm was reduced by 3 log CFU/mL from 7.3 log CFU/mL after 60 min with the bacteriophage cocktail. Therefore, we suggest that bacteriophages with depolymerase could be utilized to effectively control pathogenic E. coli in biofilm.

Feasibility Study on the Use of Liposomes for Detecting Food-borne Pathogenic Bacteria (식중독 세균 검출에 있어서 리포좀의 이용 가능성)

  • 김명희;김왕준;신원선;손동화;차성관
    • Food Science of Animal Resources
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    • v.23 no.3
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    • pp.278-283
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    • 2003
  • Feasibility tests on using liposomes for detecting food-borne pathogenic bacteria were studied with E. coli 0157:H7 as a model analyte. lmmunoliposomes, whose surface was conjugated with anti-E. coli 0157:H7 IgG and which encapsulated the marker dye, sulforhodamine B, were used for the detection label. Among the feasibility tests, the first test was to use a test-strip on which antibodies to anti-E. coli O157:H7 IgG were immobilized. In this format, immunoliposomes that did not bind to E. coli O157:H7 in sample were captured and then exhibited a visible signal which was inversely related with the number of E. coli O157:H7 in sample. The second test was a direct liposome assay followed by immunomagnetic separation. In this format, immunoliposomes which were bound to E. coli O157:H7 were lysed with detergent and produced a signal which was proportionally related with the number of E. coli O157:H7 in sample. The results from both formats indicate that liposomes can be utilized as a detection label.