An Outbreak of Foodborne Illness Caused by Enteroaggregative Escherichia coli in a High School in South Korea

Investigation of Pathogenic Escherichia coli Contamination of Vegetables Distributed in a Korean Agricultural Wholesale Market

The purpose of this study was to investigate the monthly contamination rate of pathogenic Escherichia coli, a major cause of food poisoning, in vegetables sold in agricultural wholesale markets, which distribute vegetables from all over the country, in the Incheon Metropolitan City area, South Korea, and to identify a source of the pathogen. In total, 1739 vegetables of 80 types, along with 109 soil, 67 manure, and 33 livestock feces samples, were tested for pathogenic E. coli using polymerase chain reaction, from September 2016 through August 2017. The average annual prevalence rate of vegetables was 5.8%, and the prevalence rate was above 5% from June through October. The highest prevalence rate (15.7%) was recorded in July. Water dropwort showed the highest prevalence rate (28.6%) among the vegetables examined. Pathogenic E. coli was detected in >20 types of the vegetables that were to be consumed without cooking. Among these, the prevalence rates of ponytail radish (n = 21), crown daisy (n = 86), young radish (n = 68), romaine lettuce (n = 133), perilla leaf (n = 103), Korean leek (n = 43), young Chinese cabbage (n = 68), and Chinese cabbage (n = 30) were 9.5%, 8.1%, 7.4%, 6.8%, 4.9%, 4.7%, 4.4%, and 3.3%, respectively. Among the vegetables cooked before consumption, prevalence rates were 28.6%, 27.3%, and 25.0% in wormwood, sweet potato stalk, and edible mountain vegetables (Saussurea sp., etc.), respectively. In soil, manure, and livestock feces, 36.7%, 26.9%, and 90.6% prevalence rates were confirmed, respectively. This study confirmed the pathogenic E. coli contamination of vegetables to be consumed without cooking. Therefore, to produce agricultural products that do not induce food poisoning and are safe for consumption, it is important to develop a process for killing the pathogenic microorganisms and set up a sanitary environment for effectively managing compost. In addition, it is necessary to establish surveillance systems to monitor the production chain.

Food handling practices and associated factors among food handlers working in public food and drink service establishments in Woldia town, Northeast Ethiopia

INTRODUCTION

foodborne disease (FBD) is a major public health problem globally. Inadequate food workers' knowledge, attitude, and low level of food handling practices (FHPs) may all contribute to the possibility of FBD outbreaks in public food service establishments. This study aimed to assess FHPs and associated factors among food handlers working in public food and drink service establishments in Woldia town, Northeast Ethiopia.

METHODS

an institutional-based cross-sectional study was conducted from 01 to 29, January 2017. A total of 288 food handlers were recruited through a simple random selection method. A structured interviewer-administered questionnaire and observation checklists were used to collect the respondents' socio-demographic characteristics, knowledge status on FHPs, and food handling working practices data. Descriptive statistics, bivariate and multivariate logistic regression analysis were employed using SPSS version 20 software. Those variables with a p< 0.05 were considered statistically significant.

RESULTS

out of 288 participants, 91.7% were female, and 82.3% were single, while 69.8% were literate. One hundred eighty-four (63.9%) of them were under 15-25 years of age, with a median age of 23.3 years. The proportion of good FHP was (n=134, 46.5%) (95% CI: 41.00-52.4%). Advanced age (adjusted odds ratio (AOR) =12.01, 95% CI: 1.96-73.52), education (participants who attend grades 7-12 (AOR=2.33, 95% CI: 1.14-4.79), and above secondary education (AOR=2.29, 95% CI: 1.05-4.61), work experience above six years (AOR=2.43, 95% CI: 2.08-3.17), received formal training (AOR=1.79, 95% CI: 1.68-4.71), and inspection visits by a concerned body (AOR=2.24, 95% CI: 1.05-3.09) were factors positively associated with handling practices.

CONCLUSION

the study revealed that FHP in the study area was low. Age, education, service year, training received and sanitary inspection visits by the regulatory personnel were factors significantly associated with FHPs. This finding highlights the importance of employing regular sanitary inspection visits to public food service establishments by the concerned authority to ensure that all food handlers have the knowledge and the skill to provide safe food.

Recent (2011-2017) foodborne outbreak cases in the Republic of Korea compared to the United States: a review

This study analyzes and compares foodborne disease outbreaks reported in the Republic of Korea (KR) and the United States (US) during 2011-2017. The foodborne outbreaks data in the KR and the US were collected from the Ministry of Food and Drug Safety and from the Surveillance for Foodborne Disease Outbreaks United States, respectively. The average number of outbreaks and illness population were higher in the US than in the KR, but the KR's illness ratio considering population size was 2.4 times higher than that of the US. When the sites of outbreaks compared, the number of illness was the highest at schools in the KR whereas outbreaks at restaurants were more frequent in the US. In the KR, bacterial infections were the primary cause of outbreaks while bacterial and viral infections accounted for the largest share of outbreaks in the US. Specifically, pathogenic E. coli presented a significant risk in the KR whereas Salmonella was the most prevalent in the US. These results indicate that the main microbiological targets for detection and control in the KR should differ from the US, which should be considered for developing food safety related policies.

Co-infection With Chromosomally-Located bla CTX-M-14 and Plasmid-Encoding bla CTX-M-15 in Pathogenic Escherichia coli in the Republic of Korea

The emergence of third-generation cephalosporin resistance in Escherichia coli is increasing at an alarming rate in many countries. Thus, the aim of this study was to analyze co-infecting bla _CTX-M-producing pathogenic E. coli isolates linked to three school outbreaks. Among 66 E. coli isolates, 44 were identified as ETEC O25, an ETEC isolate serotype was O2, and the other 21 were confirmed as EAEC O44. Interestingly, six patients were co-infected with EAEC O44 and ETEC O25. For these isolates, molecular analysis [antibiotic susceptibility testing, identification of the β-lactamase gene, multilocus sequence typing (MLST), and pulsed-field gel electrophoresis (PFGE)] was performed for further characterization. In addition, the transmission capacity of bla _CTX-M genes was examined by conjugation experiments. Whole-genome sequencing (WGS) was performed on representative EAEC O44 and ETEC O25 isolates associated with co-infection and single-infection. All isolates were resistant to cefotaxime and ceftriaxone. All EAEC isolates carried the bla _CTX-M-14 gene and all ETEC isolates the bla _CTX-M-15 gene, as detected by multiplex PCR and sequencing analysis. Sequence type and PFGE results indicated three different patterns depending on the O serotype. WGS results of representative isolates revealed that the ETEC O25 strains harbored bla _CTX-M-15 located on IncK plasmids associated with the Δbla _TEM-bla _CTX-M-15-orf477 transposon. The representative EAEC O44 isolates carried bla _CTX-M-14 on the chromosome, which was surrounded by the ISEcp1-bla _CTX-M-14-IS903 transposon. To the best of our knowledge, this is the first report of co-infection with chromosomally located bla _CTX-M-14 and plasmid-encoding bla _CTX-M-15 in pathogenic E. coli. Our findings indicate that resistance genes in clinical isolates can spread through concurrent combinations of chromosomes and plasmids.

Description of Kinetic Behavior of Pathogenic Escherichia coli in Cooked Pig Trotters under Dynamic Storage Conditions Using Mathematical Equations

A dynamic model was developed to predict the Escherichia coli cell counts in pig trotters at changing temperatures. Five-strain mixture of pathogenic E. coli at 4 Log CFU/g were inoculated to cooked pig trotter samples. The samples were stored at 10°C, 20°C, and 25°C. The cell count data was analyzed with the Baranyi model to compute the maximum specific growth rate (μ_max) (Log CFU/g/h) and lag phase duration (LPD) (h). The kinetic parameters were analyzed using a polynomial equation, and a dynamic model was developed using the kinetic models. The model performance was evaluated using the accuracy factor (A_f), bias factor (B_f), and root mean square error (RMSE). E. coli cell counts increased (p<0.05) in pig trotter samples at all storage temperatures (10°C–25°C). LPD decreased (p<0.05) and μ_max increased (p<0.05) as storage temperature increased. In addition, the value of h₀ was similar at 10°C and 20°C, implying that the physiological state was similar between 10°C and 20°C. The secondary models used were appropriate to evaluate the effect of storage temperature on LPD and μ_max. The developed kinetic models showed good performance with RMSE of 0.618, B_f of 1.02, and A_f of 1.08. Also, performance of the dynamic model was appropriate. Thus, the developed dynamic model in this study can be applied to describe the kinetic behavior of E. coli in cooked pig trotters during storage.

Microbial Contamination of Fresh Produce: What, Where, and How?

Promotion of healthier lifestyles has led to an increase in consumption of fresh produce. Such foodstuffs may expose consumers to increased risk of foodborne disease, as often they are not subjected to processing steps to ensure effective removal or inactivation of pathogenic microorganisms before consumption. Consequently, reports of ready-to-eat fruit and vegetable related disease outbreak occurrences have increased substantially in recent years, and information regarding these events is often not readily available. Identifying the nature and source of microbial contamination of these foodstuffs is critical for developing appropriate mitigation measures to be implemented by food producers. This review aimed to identify the foodstuffs most susceptible to microbial contamination and the microorganisms responsible for disease outbreaks from information available in peer-reviewed scientific publications. A total of 571 outbreaks were identified from 1980 to 2016, accounting for 72,855 infections and 173 deaths. Contaminated leafy green vegetables were responsible for 51.7% of reported outbreaks. Contaminated soft fruits caused 27.8% of infections. Pathogenic strains of Escherichia coli and Salmonella, norovirus, and hepatitis A accounted for the majority of cases. Large outbreaks resulted in particular biases such as the observation that contaminated sprouted plants caused 31.8% of deaths. Where known, contamination mainly occurred via contaminated seeds, water, and contaminated food handlers. There is a critical need for standardized datasets regarding all aspects of disease outbreaks, including how foodstuffs are contaminated with pathogenic microorganisms. Providing food business operators with this knowledge will allow them to implement better strategies to improve safety and quality of fresh produce.

Enteroaggregative Escherichia coli

Enteroaggregative Escherichia coli (EAEC, formerly known as "EAggEC") cause acute or persistent watery diarrhoea (with or without mucus) in children, predominantly in low-income countries, and are associated with travellers' diarrhoea in children and adults in middle and high income countries. The diverse nature of EAEC is such that not all strains cause disease. Conversely, certain strains of EAEC possess additional virulence determinants associated with the ability to cause severe diarrhoea and other symptoms, which might be life-threatening in vulnerable patients. The EAEC virulence factors described to date are either encoded on the large virulence plasmid of EAEC (plasmid of aggregative adherence) or on pathogenicity islands on the chromosome. Testing of food and faecal samples involves the detection of EAEC-associated traits in the matrix followed by isolation of the organism and confirmation of the presence of EAEC-associated genes using PCR. The variability of the plasmid structure and virulence gene sequences and the possibility that this mobile genetic element may be lost has necessitated the inclusion of chromosomal markers in the molecular screening assays. There is evidence in the literature of foodborne transmission of EAEC, but currently no evidence of a zoonotic reservoir. Fimbriae-mediated adhesion and biofilm formation are likely to be involved in both clinical manifestations of infection and attachment to foodstuffs. Multidrug resistance appears to be common in EAEC and geographically widespread. Whole-genome sequencing has revealed the mosaic genomic structure of EAEC and provided evidence that horizontal gene transfer and recombination are the driving force for acquisition of novel genome features and potentially novel pathogenic mechanisms. This has significant public health implications in terms of the diversity and pathogenesis of EAEC and its ability to colonise and cause disease in the human host.

A waterborne outbreak of multiple diarrhoeagenic Escherichia coli infections associated with drinking water at a school camp

BACKGROUND

In June 2015, a local public health laboratory was notified that students had developed gastroenteritis symptoms after attending a camp. An outbreak investigation was conducted to determine the extent and cause of the outbreak.

METHOD

A retrospective cohort study was conducted to determine the correlations between the illness and specific exposures at the school camp. All attendees were interviewed with a standard questionnaire that addressed clinical symptoms, food consumption, and environmental exposures. Clinical specimens were cultured using standard microbiological methods for bacterial and viral pathogens. The genetic relationships of all isolates were determined using pulsed-field gel electrophoresis (PFGE).

RESULTS

A total 188 patients with symptoms of diarrhoea, abdominal pain, and nausea were identified. The completed questionnaires suggested that the consumption of drinking water was likely to be linked to this outbreak. Using microbiological methods, enterohaemorrhagic Escherichia coli, enteropathogenic E. coli, and enteroaggregative E. coli were isolated, and the isolates from both patient stool and environmental water samples displayed indistinguishable XbaI-PFGE patterns. The water system in the camp used groundwater drawn from a private underground reservoir for cooking and drinking. The environmental investigation revealed some problems with the water supply system, such as the use of inappropriate filters in the water purifier and a defect in the pipeline between the reservoir and the chlorination device.

CONCLUSIONS

This outbreak points to the importance of drinking water quality management in group facilities where underground water is used and emphasizes the need for periodic sanitation and inspection to prevent possible waterborne outbreaks.

Outbreak of CTX-M-15-Producing Enterotoxigenic Escherichia coli O159:H20 in the Republic of Korea in 2016

We investigated an outbreak of enterotoxigenic Escherichia coli (ETEC) O159:H20 associated with the consumption of a tossed-noodle dish in a high school in 2016. Thirty-three ETEC strains isolated from clinical and food samples were genetically indistinguishable. The outbreak strains were resistant to third-generation cephalosporins and harbored a bla_CTX-M-15 gene on a 97-kb self-transferable IncK plasmid. This is the first outbreak caused by CTX-M-15-producing ETEC strains.

Genetic Virulence Profile of Enteroaggregative Escherichia coli Strains Isolated from Danish Children with Either Acute or Persistent Diarrhea

Enteroaggregative Escherichia coli (EAEC) is frequently found in diarrheal stools worldwide. It has been associated with persistent diarrhea, weight loss, and failure to thrive in children living in developing countries. A number of important EAEC virulence genes are identified; however, their roles in acute and persistent diarrhea have not been previously investigated. The aim of this study was to identify specific EAEC virulence genes associated with duration and type of diarrhea in Danish children. We aimed to improve the current diagnostics of EAEC and enable targeting of strains with an expected severe disease course. Questionnaires answered by parents provided information regarding duration of diarrhea and presence of blood or mucus. A total of 295 EAEC strains were collected from children with acute (≤7 days) and persistent diarrhea (≥14 days) and were compared by using multiplex PCR targeting the genes sat, sepA, pic, sigA, pet, astA, aatA, aggR, aaiC, aap, agg3/4C, ORF3, aafA, aggA, agg3A, agg4A, and agg5A. Furthermore, the distribution of EAEC genes in strains collected from cases of bloody, mucoid, and watery diarrhea was investigated. The classification and regression tree analysis (CART) was applied to investigate the relationship between EAEC virulence genes and diarrheal duration and type. Persistent diarrhea was associated with strains lacking the pic gene (p = 0.002) and with the combination of the genes pic, sat, and absence of the aggA gene (p = 0.05). Prolonged diarrhea was associated with the combination of the genes aatA and astA (p = 0.03). Non-mucoid diarrhea was associated with strains lacking the aatA gene (p = 0.004). Acute diarrhea was associated with the genes aggR, aap, and aggA by individual odds ratios. Resistance toward gentamicin and ciprofloxacin was observed in 7.5 and 3% of strains, respectively. Multi-drug resistance was observed in 38% of strains. Genetic host factors have been associated with an increased risk of EAEC-associated disease. Therefore, we investigated a panel of risk factors in two groups of children—EAEC-positive and EAEC-negative—to identify additional factors predisposing to disease. The duration of breastfeeding was positively correlated with the likelihood of belonging to the EAEC-negative group of children.

Community-acquired Escherichia coli Enteritis in Korean Children: The Clinical Application of a Stool Polymerase Chain Reaction Assay

Background

Although Escherichia coli is a common cause of bacterial enteritis in Korea, reports on community-acquired E. coli enteritis in Korean children are scarce. This study aimed to determine the clinical characteristics and pathotype distribution of community-acquired E. coli enteritis diagnosed by a multiplex polymerase chain reaction (PCR) assay in Korean children.

Materials and Methods

The medical records of children aged 18 years or less who were diagnosed with acute gastroenteritis by the attending physician between 2013 and 2016 were retrospectively reviewed. The clinical characteristics of children diagnosed with E. coli enteritis were investigated and compared with those diagnosed with Salmonella enteritis. E. coli and Salmonella infections were diagnosed by a stool PCR assay.

Results

Among 279 children, in whom PCR assays for E. coli and Salmonella spp. were performed, Salmonella enteritis and E. coli enteritis were diagnosed in 43 (15.4%) and 39 (14.0%) children, respectively. Among the 39 children with E. coli enteritis, enteropathogenic E. coli (n=21, 53.8%) and enteroaggregative E. coli (n=15, 38.4%) were the most common causative agents. Empirical antibiotics were administered to 33 (84.6%) children. A total of 31 (79.5%) children developed fever, and 25 (80.6%) of them had the fever for 3 days or less, which resolved a median of 1 day (range 0-3 days) after hospitalization. The most frequent gastrointestinal symptom was diarrhea (n=36, 92.3%). Significantly more children with E. coli enteritis were aged 2 years or less as compared with those with Salmonella enteritis (41.0% vs. 21.9%, P = 0.021). Children with Salmonella enteritis more frequently complained of fever (97.7% vs. 79.5%, P = 0.012), abdominal pain (90.7% vs. 64.1%, P = 0.004), and hematochezia (46.5% vs. 10.3%, P <0.001) than those with E. coli enteritis. Erythrocyte sedimentation rate and C-reactive protein levels were significantly higher in children with Salmonella enteritis than those with E. coli enteritis (P <0.001).

Conclusion

Enteropathogenic E. coli was the most frequent pathotype in Korean children with E. coli enteritis that caused mild clinical symptoms. A stool PCR assay for E. coli may be useful for epidemiological purpose and for an early diagnosis of E. coli enteritis.

Enteroaggregative Escherichia coli in Daycare-A 1-Year Dynamic Cohort Study

Enteroaggregative Escherichia coli (EAEC) has been associated with persistent diarrhea, reduced growth acceleration, and failure to thrive in children living in developing countries and with childhood diarrhea in general in industrialized countries. The clinical implications of an EAEC carrier-status in children in industrialized countries warrants clarification. To investigate the pathological significance of an EAEC carrier-state in the industrialized countries, we designed a 1-year dynamic cohort study and performed follow-up every second month, where the study participants submitted a stool sample and answered a questionnaire regarding gastrointestinal symptoms and exposures. Exposures included foreign travel, consumption of antibiotics, and contact with a diseased animal. In the capital area of Denmark, a total of 179 children aged 0–6 years were followed in a cohort study, in the period between 2009 and 2013. This is the first investigation of the incidence and pathological significance of EAEC in Danish children attending daycare facilities. Conventional microbiological detection of enteric pathogens was performed at Statens Serum Institute, Copenhagen, Denmark, and at Hvidovre Hospital, Copenhagen, Denmark. Parents completed questionnaires regarding gastrointestinal symptoms. The EAEC strains were further characterized by serotyping, phylogenetic analysis, and susceptibility testing. EAEC was detected in 25 (14%) of the children during the observational period of 1 year. One or more gastrointestinal symptoms were reported from 56% of the EAEC-positive children. Diarrhea was reported in six (24%) of the EAEC positive children, but no cases of weight loss, and general failure to thrive were observed. The EAEC strains detected comprised a large number of different serotypes, confirming the genetic heterogeneity of this pathotype. EAEC was highly prevalent (n = 25, 14%) in Danish children in daycare centers and was accompanied by gastrointestinal symptoms in 56% of the infected children. No serotype or phylogenetic group was specifically linked to children with disease.