• Journal of Dairy Science and Biotechnology
• /
• 제39권2호
• /
• pp.51-62
• /
• 2021

Escherichia coli are the predominant facultative bacteria found in the gastrointestinal tract of animals and humans. Some strains of E. coli that acquire virulence factors and cause foodborne and waterborne diseases in humans are called pathogenic E. coli and can be divided into five pathotypes according to the virulence mechanism: EAEC, EHEC, EIEC, EPEC, and ETEC. Although selective media have been developed to detect E. coli, distinguishing pathogenic strains from non-pathogenic ones is difficult because of their similar biochemical properties. Therefore, it is very important to find a new and effective diagnostic method to identify pathogenic E. coli. With recent advances in molecular biology and whole genome sequencing, the use of polymerase chain reaction (PCR) is increasing rapidly. In this review paper, we provide an overview of pathogenic E. coli and present a review on PCR detection methods that can be used to diagnose pathogenic E. coli. In addition, the possibility of real-time PCR incorporating IAC is introduced. Consequently, this review paper will contribute to solving the current challenges related to the detection of pathogenic E. coli.

• 한국식품과학회지
• /
• 제51권6호
• /
• pp.604-609
• /
• 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.

• 한국동물위생학회지
• /
• 제46권1호
• /
• pp.35-45
• /
• 2023

Pathogenic Escherichia coli is the cause of a wide range of diseases in pigs, including diarrhea, edema disease, and septicemia. Diarrhea caused E. coli may result in significant economic losses, making pathogenic E. coli an important pathogen for the swine industry. This study investigated the prevalence of virulence factor genes, antimicrobial resistance phenotypes, and resistance genes in E. coli isolated from feces of piglets in Korea between 2017 and 2020. As a result, 119 pathogenic E. coli isolates were obtained from 601 fecal samples. The F4 adhesin gene and the STb enterotoxin gene were commonly present in E. coli isolated from diarrhea samples. The dominant virulotypes of isolates from diarrhea samples were STb, Stx2e, and F4:LT:STb. More than 80% of the screened isolates were resistant to ampicillin, sulfisoxazole, chloramphenicol, or tetracycline. To confirm the resistance mechanisms for β-lactam or quinolone, we investigated the genotypic factors of resistance. Each of the ceftiofur-resistant E. coli produced an extended-spectrum β-lactamase encoded by bla_CTX-M-14, bla_CTX-M-27, and bla_CTX-M-55. And all ciprofloxacin-resistant E. coli harbored mutations in quinoloneresistance-determining-regions. In addition, some of the ciprofloxacin-resistant E. coli contained the plasmid-mediated-quinolone-resistance genes such as qepA, qnrB1, or qnrD. This study has confirmed that the F4 fimbria and the STb enterotoxin are the most predominant in pathogenic E. coli isolated from piglets with diarrhea in Korea and there is a great need for responsible and prudent use of antimicrobials to treat colibacillosis.

• 농업과학연구
• /
• 제42권3호
• /
• pp.201-205
• /
• 2015

The experiment was conducted to evaluate the effects of pathogenic Escherichia coli on diarrhea, growth performance, and blood profile of weaned pigs. A total of 48 pigs were used and housed in individual pens of disease containment chambers for 16 d (4 d before and 12 d after the first challenge [d0]). The treatments were with or without the pathogenic E. coli challenge (F-18 E. coli strain; heat-labile, heat-stable, and Shiga-like toxins). Pigs were orally inoculated with a dose of $10^{10}cfu$ E. coli per 3 mL PBS daily for 3 days. The common nursery diet and water were available at all times. The ADG, ADFI, G:F, diarrhea score, ratio of fecal ${\beta}$-hemolytic coliforms from total coliforms (RHT), and blood profile were measured. The pathogenic E. coli reduced (P < 0.05) ADG from d0 to 6 (117 vs. 297 g/d) and from d0 to 12 (377 vs. 238 g/d) compared with the control. Meanwhile, the pathogenic E. coli increased (P < 0.05) diarrhea score (average 3.4 vs. 1.4) and RHT (average 82 vs. 11%) on d3, 6, and 9 and the number of white blood cells (17.59 vs. $13.48{\times}10^3/{\mu}L$) on d6 compared with the control. No differences were found on ADFI and others in the blood profile (total protein and hematocrit). In conclusion, pathogenic E. coli used in this experiment successfully caused mild diarrhea, increased number of white blood cells, and adversely affected growth rate of weaned pigs.

• 한국축산식품학회지
• /
• 제37권6호
• /
• pp.799-803
• /
• 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.

• 한국환경보건학회지
• /
• 제46권3호
• /
• pp.353-358
• /
• 2020

Objectives: An outbreak of pathogenic Escherichia coli food poisoning in Korea was first reported in 1998. They have continued to occure since then. This study was performed to describe the long-term trend in pathogenic E. coli food poisoning occurrences in Korea and examine the relation with climate factors. Methods: Official Korean statistics on food poisoning outbreaks and meteorological data for the period 2002-2017 were used. Pearson's correlation analysis was employed to establish the relationship between outbreaks of pathogenic E. coli food poisoning and meteorological factors. The influence of meteorological factors upon the outbreaks was analyzed by regression analysis. Results: During the study period, pathogenic E. coli food poisoning ranked second for the number of outbreaks (excluding unknowns) and first for the number of cases. Average temperature, the highest and lowest temperatures, precipitation, number of days with rainfall, and humidity all had a significant correlation with monthly number of outbreaks of pathogenic E. coli food poisoning (p<0.001). It was found that the lowest and highest temperatures and precipitation had a significant influence on the monthly number of outbreaks of food poisoning (p<0.001). These variables together explained 42.1% of the total variance, with the lowest temperature having the greatest explanatory power. Conclusion: These results show that food poisoning incidences may have been influenced by climate change, especially warming. The results also suggest that pathogenic E. coli infections are now an important public health issue in Korea since it is one of the countries where climate change is occurring rapidly.

• 대한수의학회지
• /
• 제39권3호
• /
• pp.554-559
• /
• 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.

• 미생물학회지
• /
• 제11권4호
• /
• pp.175-180
• /
• 1973

This study was attempted to see more clear relationships among the enterobacteria, especially between the intestinal normal flora and pathogenic bacteria. It has been known that some intestinal normal flora produce the bactrial metabolites that are harmful to other enteric bacteria. One of the metabolites is known as colicin, the protein fraction, which possesses certain degree of inhibitory effect against other bacterial growth fraction, whih possesses certain degree of inhibitory effect against other bacterial growth. As a preliminary study for a colicin purification, the antagonistic effect of E, coli to groups of Salmonella and Shigella has been studied by means of in vitro quantitative culture method. 1. E.coli showed definite inhibitory effects aganist both Salmonella and Shigella groups in the mixture of two organisms. 2. The inhibitory effects of E.coli in the E.coli-Salmonella and the E.coli-Shigella mixture occurred from 4 hours incubation following the inoculation. 3. Even the complete inhibition of pathogenic enteric bacterial growth was noticed in the E.coli-Salmonella mixture at overnight incubation. 4. Among the diluted mixtures, 1:100, 1:1,000, and 1:10,000, survival rate of pathogenic enteric bacteria in the mixtures with E.coli showed least affected at the 1:1,000 dilution. 5. It was found that the antagonistic effect aganist groups of Salmonella-shigella was depending upon the groups of the genera.

• 한국미생물·생명공학회지
• /
• 제48권2호
• /
• pp.121-128
• /
• 2020

Diarrhea is a major public health concern associated with pathogenic Escherichia coli infections. Food-borne pathogenic E. coli can lead to large diarrheal outbreaks and hence, there is a need to estimate the frequency of pathogenic E. coli load in the various types of meat available in markets. In the present study, we classified and characterized diarrheagenic E. coli isolates collected from 399 raw meat samples from retail sources in Korea. Shiga toxin-producing E. coli (STEC) were detected in 11 (9.7%) samples, including nine strains (8.0%) in beef and two strains (1.8%) in chicken. The frequency of the detected virulence markers were as follows: astA, 28.3%; escV,18.6%; eaeA,17.7%; ent, 7.0%; EHEC-hly, 4.4%; stx1, 3.5%; and stx2, 3.5%. We did not observe any typical EPEC, EIEC, or ETEC virulence determinants in any of the samples. The STEC serotype O26 was detected in one sample, but no other serogroups (O91, O103, O128, O157, O145, O111, and O121) were found. Further research is needed to better understand the virulence mechanism of STEC serotypes, their ecology, and prevalence in animals, food, and the environment. These results will help improve risk assessment and predict the sources of food poisoning outbreaks.

• Journal of Dairy Science and Biotechnology
• /
• 제39권2호
• /
• pp.68-77
• /
• 2021

This study aimed to evaluate the effects of antibacterial activity of Tibetan mushroom exopolysaccharide against foodborne pathogenic bacteria Staphylococcus aureus 305, Listeria monocytogenes ATCC19114, Escherichia coli O157:H7 ATCC42894 and Escherichia coli O55. The yield of exopolysaccharide isolated from Tibetan mushroom culture was 620 mg/L. The antibacterial activity of exopolysaccharide against foodborne pathogenic bacteria exhibited 15 mm and 12 mm clear zone against S. aureus 305 and L. monocytogenes ATCC 19114, respectively. However, no clear zone was observed against E. coli O157:H7 ATCC 42894 and E. coli O55. In conclusion, exopolysaccharide isolated from Tibetan mushroom culture have the antibacterial activity only against Gram-positive foodborne pathogenic bacteria.