Enteropathogenic Escherichia coli Outbreak and its Incubation Period: Is it Short or Long?

Pathophysiology of enteropathogenic Escherichia coli during a host infection

Enteropathogenic Escherichia coli (EPEC) is a major cause of infantile diarrhea in developing countries. However, sporadic outbreaks caused by this microorganism in developed countries are frequently reported recently. As an important zoonotic pathogen, EPEC is being monitored annually in several countries. Hallmark of EPEC infection is formation of attaching and effacing (A/E) lesions on the small intestine. To establish A/E lesions during a gastrointestinal tract (GIT) infeciton, EPEC must thrive in diverse GIT environments. A variety of stress responses by EPEC have been reported. These responses play significant roles in helping E. coli pass through GIT environments and establishing E. coli infection. Stringent response is one of those responses. It is mediated by guanosine tetraphosphate. Interestingly, previous studies have demonstrated that stringent response is a universal virulence regulatory mechanism present in many bacterial pathogens including EPEC. However, biological signficance of a bacterial stringent response in both EPEC and its interaction with the host during a GIT infection is unclear. It needs to be elucidated to broaden our insight to EPEC pathogenesis. In this review, diverse responses, including stringent response, of EPEC during a GIT infection are discussed to provide a new insight into EPEC pathophysiology in the GIT.

Quantitative microbial risk assessment of pathogenic Escherichia coli in commercial kimchi in South Korea

Owing to convenience, ease of preparation, and price, the consumption of commercial kimchi is gradually rising in South Korea. Here, we estimated the risk level posed by pathogenic Escherichia coli in commercial kimchi products using the quantitative microbial risk assessment (QMRA) approach to develop measures for preventing potential foodborne outbreaks from kimchi consumption. We collected 610 samples of commercial kimchi products produced in Korea, 267 kimchi samples from foreign countries imported to Korea, and 187 raw materials used in kimchi preparation, and analyzed them for contamination with pathogenic E. coli. A Predictive model was developed to observe the survival characteristics of pathogenic E. coli. A dose-response model was selected, and the risk level was estimated using @RISK software. Although a prior epidemiological study indicated the frequent occurrence of foodborne outbreaks arising from contaminated kimchi products consumed in food service facilities, we found a low probability of foodborne illness caused by pathogenic E. coli in commercial kimchi products.

Diarrheal outbreak caused by atypical enteropathogenic Escherichia coli O157:H45 in South Korea

Background: In May 2013, an outbreak of gastroenteritis occurred in a high school in Incheon, South Korea. We investigated the outbreak in order to identify the pathogen and mode of transmission.

MATERIALS AND METHODS

A case-control study was performed using standardized questionnaires with a case definition of illness with diarrhea. Stool samples, environmental samples, and samples from preserved food items were collected to test pathogens. Pulsed-field gel electrophoresis (PFGE) was performed on the outbreak-related Escherichia coli strains.

RESULTS

Thirty-three people (attack rate: 2.5%) met the case definition, and the pattern of the epidemic curve suggested a point-source outbreak. The common symptoms of cases were diarrhea (100.0%), abdominal pain (75.8%), chills (45.5%), and nausea (39.4%). Cases were found to be 8.26 times more likely to have eaten spicy fish soup with cod (95% confidence interval: 1.05-65.01). Consumption of egg soup with spring onions or braised eggs with razor clam flesh was significantly associated with illness. Atypical enteropathogenic E. coli O157:H45 was isolated from samples of 9 cases (27.3%) and tuna bibimbap. PFGE patterns of all tested isolates of O157 serotype were indistinguishable.

CONCLUSIONS

This outbreak was caused by atypical enteropathogenic E. coli O157:H45 and the food vehicle was suspected to be tuna bibimbap. The statistical analysis was not in concordance with the microbiologic tests, probably owing to low pathogenicity of atypical enteropathogenic E. coli O157. This is the first report of an outbreak caused by atypical enteropathogenic E. coli O157.