1. Introduction

Escherichia coli O157:H7 is a serotype of Escherichia coli (E. coli) bacteria that is responsible for causing food borne diseases. Serotype refers to the different groups of one particular microorganism which differs from each other in terms of surface structures. Improperly sterilized or contaminated raw and undercooked food is usually seen to cause E. coli O157:H7 infection. This bacterial serotype produces shiga-like toxins and infects individuals resulting in non-hemorrhagic or hemorrhagic diarrhoea along with abdominal cramps and these symptoms last approximately 5 to 10 days. Aim of this study is to critically examine the consequences of E. coli O157:H7 infection from the selected case study. The case study in concern is “Investigation into a national outbreak of STEC O157:H7 associated with frozen beef burgers, UK, 2017”.

2. Overview of Case Study

Shiga-like toxin producing Escherichia coli (STEC) O157:H7 is considered to be a zoonotic pathogen that can cause gastrointestinal diseases in the human body. Zoonotic pathogens are those who cause pathogenic conditions in humans jumping straight from a non-human agent. Over 700 cases of infections caused by these bacteria are being reported every year in the UK and therefore is a serious threat to public health in this country. The reported cases range from mild to severe bloody diarrhoea and Haemolytic Uraemic Syndrome (HUS) is another multisystem disorder shown to cause complications in 5-15% of the cases (Pezeshkian et al. 2017). However, the degree of severity depends on the gender, age and previous medical records of the individual. Cattle and Sheep are considered to be the natural reservoirs of E. coli O157:H7 in the UK. Direct or indirect contacts of humans with these zoonotic agents or consumption of contaminated foods derived or came in contact with them are causing diseases in this country.

Most of the STEC O157:H7 outbreaks are reported to be sporadic, however, the rest of the cases comprise. According to this case study, the reported cases are mostly caused by cross contaminated cooked foods, undercooked meats, raw milk and milk products, salads and contaminated vegetables. Importance of delivery vehicles are an unavoidable factor in cases of these outbreaks. However, after implementation of proper hygiene practices in the 1990s, meat and other stored food related outbreaks have been reduced. Increased cases are now related to freshly produced food products in the UK. Whole Genome Sequencing (WGS) of STEC has been appointed since 2015 to diagnose people with infection of the same (Nazareth et al. 2019). The selected case study is based on an outbreak detected by Public Health England (PHE) on November 13, 2017. Four cases of STEC O157:H7 were detected in the UK and those were of the same phage type (PT2) and within five SNPs of each other.

Faecal samples of the patients were tested for the presence of STEC O157:H7 and one confirmed case belonged from a SNP designated as 9.148.298.681.4005.4232.%. Moreover, this case was shown to have an onset date of at least September 28 of 2017.

PHE undertook all the retrospective and prospective case details of STEC O157:H7 by researching PT and WGS data of reported STEC cases in 2017 in the UK (Wordofa et al. 2017). Moreover, they published the accession number of WGS on the Epidemic Intelligence Information System to confirm any other similar cases in the country. In addition, PHE started a surveillance system called National Enhanced Surveillance System for STEC (NESSS) from 2009 in England. Patients were asked about their food consumption from the last few days, food brands, store name and place of purchase, storage duration after purchasing, their food habits and past medical records. Detailed investigations about the food supply chain were performed by Food Standard Agency (FSA) in collaboration with Local Authority (LA). All the collected samples were tested in the PHE Food, Water and Environmental (FW&E) laboratory.

All the 12 detected cases were confirmed to be caused by STEC O157:H7, phage type was PT2 and the harbouring stx subtype was stx2a. Further WGS analysis showed that the nine of the cases were identical; however, three of them differed from the profile of outbreak by 1-2 SNPs (Byrne et al. 2020). The reported strain was new and at least was not detected at past three years of routine surveillance in England. However, the strain belonged to the STEC O157:H7 clade and the suspected origin were domestic areas of the UK. Evident onset of all the cases were between September 28 of 2017 and November 23 of 2017 (Wright et al. 2017). Eleven of the cases were reported from England itself and the last one was from Scotland and nine of the patients were males and three of them were females.

Figure 1: Timeline of Key Events in the Investigation

(Source: Byrne et al. 2020)

Age ranges of the patients were between 1 and 65 with a median of 16 years age. All of them reported to suffer from bloody diarrhoea and 10 among them felt severe abdominal cramps. Seven of the reported cases were diagnosed with vomit and five others were reported to have high temperature. Four individuals of the outbreak developed HUS and eight victims were hospitalized with other defined symptoms. However, no death cases were recorded during this outbreak caused by STEC O157:H7 in the UK (Ibrahim et al. 2019). Moreover, according to the recorded details of patients, eleven of them did not have any common exposure. None among the twelve individuals travelled to foreign countries in seven days before the onset date. However, three of them confronted their direct or indirect contacts with ruminants in their local areas (Byrne et al. 2020). Therefore, the vast geographical distribution of the outbreaks suggests that the origin of the incident must be an international food distribution channel.

After the inspection of the food chain, Retailer A was proved to be responsible for 90.9% of the cases that is 10 among the 11 cases. Overall thirteen categories of food exposure were reported in the outbreak and twenty items among those are often found to be significant in the outbreak record. Significantly, beef products supplied by Retailer A occupied most of the items listed (Byrne et al. 2020). Moreover, ten other cases were detected between December 8 of 2017 and December 11 of 2017 and they were infected from burger and mince products (Byrne et al. 2020). Nine of these individuals were buyers of Retailer A and one was of Retailer B. Data from the food chain investigation is given in the following figures.

Figure 2: Shopping Frequency of UK national Supermarkets (Outbreak Cases)

(Source: Byrne et al. 2020)

Figure 3: Food Exposure Frequencies among STEC cases

(Source: Byrne et al. 2020)

Figure 4: Results of Laboratory Tests of Samples Collected During Outbreak

(Source: Byrne et al. 2020)

3. Contradictory Consequences

The food borne disease outbreak of 2017 in the UK caused by STEC O157:H7 harmed twenty two people in the duration between September and December of the year. Past records of this infection in the country had contributed to the declaration that STEC is a major threat to public health. The outbreak of 2017 has affected people along with the food retailing business and supply chain of the country (Coulombe et al. 2020). However, if this was not the consequence of the contamination of foods and only a few individuals were affected, there would have been some contradictory consequences. Those consequences would mostly be related to business and supply chain of foods in the UK.

• According to surveys, one restaurant in the UK serves more than 60 billion meals per year. Constant cases of STEC O157:H7, even in low numbers can be predicted to cause huge economic loss as orders will be reduced (Pang et al. 2017). On diagnosis of infection caused by food consumed in that restaurant, customers will not be interested to visit there again leading to destruction of the customer base of those restaurants.
• More than 10% of the people in the UK are employed in the food industry and restaurants. Continuous economic loss of these sectors can be said to cause huge unemployment in the country (Brosel-Oliu et al. 2018).
• According to Marketwatch, 18% of stock decrease was seen after the incident of Chipotle in 2015. The UK market can be predicted to experience a downfall of market share by almost 30% if the consequence of food contamination was not an outbreak (de Oliveira et al. 2018).
• Suffering individuals of the outbreak can demand for refund from the restaurant authority and brand managers. According to reports, this refund can cost restaurants and food brands up to 800 billion Euros (Kang et al. 2019). This huge amount can cause economic loss of the manufacturing brands and eateries.
• Lockout in the food manufacturing plants due to improper safety and cleaning measures will cause unemployment and shortage of production in the company (Ngnitcho et al. 2018).
• Vehicles appointed for the delivery of the food products will be harmful for the drivers as it will result in their unemployment (Hassan et al. 2019). Therefore, this is a negative consequence by which organisational behaviour can be hampered in an irrelevant way. Furthermore, food contamination delivers negativity for global food sectors by which set up can be modified in an inaccurate manner with huge loss.

4. Analysis

Proper sterilization methods have to be improvised in every food manufacturing plant in terms of maintaining product quality. In terms of sterilization, filtration, irradiation, pasteurization, heating methods have to be applied in the plant. Pasteurization has to be maintained after every step of producing milk based products with temperatures lower than 100 degrees centigrade and high pressure (Ngnitcho et al. 2018). This can also be applied to the production plants of fruit juices as application of high heat is responsible for degradation of juice quality. Moreover, liquid foods can be subjected to micro filtration that will eliminate unnecessary microbial contents from the food product. However, filtration cannot be applied for liquids which contain ingredients of large sizes and are insoluble. In such cases, irradiation can be an option that will include sterilization by Ultraviolet (UV) rays, Infrared (IR) rays and Gamma rays (Kang et al. 2019). However, irradiation is most appropriate for the sterilization of packaged foods and foods with an uneven surface.

Production of food in a heated condition is efficient in terms of killing microorganisms and other contaminating agents. Moreover, a dry environment is responsible for preventing the growth of fungal agents that is one of the most frequent cases reported in terms of food borne diseases (Mukhopadhyay et al. 2019). Maintaining proper freezing temperatures in case of long term storage is essential in terms of prevention of any microbial growth. In addition, pulsed light treatment of the foods is currently the top rated method to sterilize food products. Pulsed light treatment is a preferred method as it applies very low heat for a fraction of second (Hassan et al. 2019). Light intensity in this method is almost ten times higher than sunlight and the lights used are UV and IR. Due to the high intensity of light, it can cross glass and thick paper barriers and therefore can sterilize food after packaging (Xue et al. 2017).

Sterilization of the retailing stores are also important as foods are kept here before being delivered to the customers. Therefore, even after sterilization is properly maintained in the production plant, food products can be contaminated at the retailers end. Consumers have to adhere to proper cleaning methods for their storage and cooking areas at their home (Natasha et al. 2017). Refrigerators have to be cleaned regularly and kept at suitable temperatures to avoid fungal growth and any other microbial contamination. Cooking areas have to be disinfected properly to avoid any cross contamination of the cooked foods (Xue et al. 2017). Moreover, suitable temperatures have to be maintained during cooking to make sure that all the viable organisms are dead.

In the case of restaurants, tables, plates and all other culinary materials have to be sterilized after each order served with them. Washing areas and kitchen tops have to be disinfected with effective disinfectants on a regular basis. In addition, delivery vehicles appointed for food delivery from manufacturing plants to the retailer have to be sanitized after every delivery. Moreover, in case of home delivery, proper safety and cleaning measures have to be adhered to (Wang et al. 2017). Packaging of the foods has to be done properly to avoid passage of air and avoid contamination.

5. Discussion

Outbreaks caused by STEC O157:H7 is responsible for severe health issues in the UK and more than 700 cases of the same are reported per year. From the case study it can be said that proper methods of control had not been applied for the reported cases. However, surveillance programs have been organized since 2009 and detailed investigations of the few recorded cases used to be performed.

In terms of surveillance methods, every confirmed case of STEC O157:H7 after laboratory tests were investigated with food consumption of the past seven days of Onset date. An Enhanced Surveillance Questionnaire (ESQ) was followed during the investigation of the infected individuals and the same process was followed in Scotland (Sharapov et al. 2016). Generation of hypothesis about the origin of outbreak consisted of three elements and those were analysis of ESQ data, detailed case to case inspection and further interview with trawling questionnaire (de Oliveira Elias et al. 2019). A detailed research was conducted to study the exposure of eleven outbreak cases reported in England in NESSS. These data were compared against the 537 reported primary cases which were non outbreak cases and considered as a control group (Yu et al. 2018). These eleven individuals were not associated with foreign travels and were not related with any other outbreaks.

The non outbreak cases matched the outbreak cases in terms of age group and gender. Both of the outbreak and non outbreak cases were selected on the basis of severity of symptoms and date of onset. The considered duration of onset for the study was September 1 to December 31 of years between 2009 and 2017 (Güner et al. 2017). Only the food exposures were examined for investigations and foreign travels and ruminant contact were excluded. Therefore it was a univariable inspection that was used to study the interrelation between the outbreak and non outbreak cases (Pandey et al. 2017). All the collected data from the surveys were managed and analysed in Stata v12.0 by Stata Corp, Texas (Zeinhom et al. 2018). A trawling questionnaire was used for a more detailed investigation of the patients’ food consumption (Saeedi et al. 2017).

After generating a potential hypothesis, a more focused questionnaire was used for re-interviewing the patients. This questionnaire included queries about types of food consumed, handling or storage of suspected foods. Place and store of purchase, brand name and batch code were also recorded along with the degree of freshness of the foods. All these data were stored as aide memoire of the outbreak and the loyalty cards of the infected individuals were sent to retailers (Güner et al. 2017). Retailers were requested to submit the purchase histories of those customers and also the leftovers from those batches for testing.

The Local Authority (LA) worked in collaboration with the Food Safety Agency (FSA) for detailed inspection of the food manufacturing plant. The inspection started from the raw material supplier to the delivery of the final product to the retailer. This method aimed to investigate the application of proper safety measures and maintenance of safety regulations. Environmental sampling was considered to examine the safety methods of the plant. Moreover, samples of final product and raw materials along with swabs of delivery vehicles were taken. All these collected data were submitted to FW&E laboratories for further tests.

In terms of controlling the outbreak and preventing further cases, no significant steps were taken by the UK authority (Pandey et al. 2017). Upon positive test results of STEC O157:H7 in two burgers from Retailer A, those products were removed from the shelves and sent for further investigation. These further tests were not needed as those are being discarded and investigation of the plant had already been performed. It is a fatal process and has to be controlled in a proper manner to reduce such constraints in a greater manner.

Confirmation of the phage type being PT2 on December 21 of 2017, investigators started considering all the factors such as severity of illness caused by the pathogenic agent. Long shelf life of the frozen burgers and the demand of consumers for the product were also included in their list of considerable. This step can be said to be invalid as it is quite difficult to predict the storage duration of the products at the consumers’ end (Zeinhom et al. 2018). Moreover, the outbreak started in September of the year and till December; many other batches may have been contaminated. Investigation of the plant and their products would have been an effective step to control further outbreaks.

6. Conclusion

It can be concluded from this study that proper safety regulations have not been followed in the food manufacturing plants of the UK. However, surveillance methods applied by the PHE were somewhat effective and the steps taken for operating the surveillance drive were proper. This surveillance campaign was started in 2009 that was the starting year of STEC O157:H7 records. According to the case study, more than 700 cases of infections caused by E. coli are reported in the UK hospitals every year. However, the measures taken for controlling further outbreaks were improper in terms of time and place. Testing the discarded foods after the outbreak is an invalid step as testing the manufacturing plant and their products are much needed for future safety. Moreover, proper cleaning measures are not followed in the restaurants, manufacturing plants, delivery vehicles, retailing stores and even at the customers’ end. In order to stop further spread of the contamination and lower the chances of further outbreaks, proper safety and cleaning measures have to be followed.

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