• 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$_7$.

• 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.

• 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.

• 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.

• 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.

• 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.

• Parasites, Hosts and Diseases
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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.

• 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.

• 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.

• Korean Journal of Veterinary Research
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• v.39 no.3
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• pp.554-559
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• 1999

The purpose of this study was to evaluate effect of chitosan-oligosaccharides (CHIOL) on hydrophobicity of pathogenic E coli including a field isolate from suckling piglet with diarrhea, E coli-O157 : H7, and E coli-O149 : K88ac. E coli field isolate appeared adhesion of 100% to n-hexadecane between 0.00125% and 0.05% CHIOL. E coli-O157 : H7 occurred adhesion of 69% and 64% under the level of 0.00125% and 0.025% CHIOL, respectively. E coli-O149 : K88ac showed adhesion of 100% in higher than 0.025% CHIOL. For cationic action, the adhesion of E coli isolate and E coli-O149 : K88ac to n-hexadecane were inhibited at level of higher than 10mM $Ca^{2+}$ but did not induce any difference among the concentrations used(p < 0.01). However, the adhesion of E coli-O157 : H7 to n-hexadecane was inhibited at level of higher than 50mM $Ca^{2+}$. In a field trial, control piglets showed average mortality of up to 58% during 3 days after the onset of diarrhea. In contrast, the prevalence of E coli-induced diarrhea in CHIOL-treated groups without mortality was dropped down to average 34% on the 1st day after the treatment of CHIOL, and average 2% on the 4th day. After then, piglets with diarrhea was not present. In conclusion, the low concentrations of CHIOL were most likely to associate with the enhancement of hydrophobicity to pathogenic E coli. Calcium inhibited the hydrophobicity of E coli by CHIOL. These results suggested that CHIOL could be played an efficient and reliable role in treating enteric colibacillosis of piglets.