STEC from feedlot to abattoir

Epidemiology of Shiga toxin-producing Escherichia coli in beef cattle from feedlot through to abattoir

Industry Sector: Cattle and Small Stock

Research focus area: 

  • Red Meat Safety, Nutritional Value, Consumerism and Consumer Behaviour

Research Institute: University of Pretoria

Researcher: Peter Thompson

Research Team

Title Initials Surname Highest Qualification Research Institution
Prof. A.A. Adesiyun PhD University of Pretoria
Prof. E. Madoroba PhD ARC-OVI
Dr. K. Keddy PhD NICD

Completion: 2020

Aims of the project

  • To determine the prevalence, dynamics and factors associated with shedding of Shiga-toxin producing Escherichia coli (STEC) in feedlot cattle; To determine the relationship between faecal shedding of STEC in the feedlot and on arrival at the abattoir, and carcass contamination at various steps in the slaughter process.

Executive Summary

Shiga toxin-producing Escherichia coli (STEC) has emerged as an important foodborne pathogen globally with a significant impact on public health. Healthy colonized cattle are major reservoirs of STEC and bovine “super-shedders” are considered to play a key role in the entry of STEC into the food chain. The public health relevance is determined by the pathogen’s low infectious dose and capacity to survive and be transmitted along different stages in the beef production chain. Of the over 470 different serotypes of STEC detected in humans, the O157:H7 serotype is the most frequently associated with large food and water-borne outbreaks. However, non-O157 STEC have been increasingly isolated from sporadic cases of haemorrhagic colitis and the sometimes fatal haemorrhagic uremic syndrome. In a recent RMRD-funded project a high prevalence of STEC contamination of beef products was detected in retail outlets in Pretoria, suggesting that STEC may pose a real food-borne disease threat and that further investigation of the epidemiology of the pathogen is required. Since the majority of beef consumed passes through the feedlot system, it is essential that we understand the dynamics of shedding of the organism in the feedlot in order to identify control measures to reduce the bacterial challenge resulting in carcass contamination in the abattoir.

Objective Statement

The specific objectives of the study were (i) to determine the frequency and dynamics of shedding of STEC in cattle in a feedlot; (ii) to longitudinally follow tagged study animals to slaughter to determine the frequency of STEC contamination pre-slaughter, during slaughter and post-slaughter; (iii) to characterize STEC isolates with respect to their serotypes and presence of virulence factors; and (iv) to to establish the genetic relatedness of the isolates between feedlot and abattoir.

Results

On arrival at the feedlot, 27% (29/106; 95% CI: 19-37%) of faecal samples were STEC-positive on PCR. Regarding virulence genes, 18 (17%) tested positive for stx120 (19%) were positive for stx212 (11%) were positive for eaeA and 23 (22%) were positive for hlyA. STEC prevalence during the longitudinal study indicated non-O157 STEC shedding in 92% (72/78; 95% CI: 84-97) of samples and non-O157 STEC super shedding (≥4llog10 CFU/g faeces) in 73% (57/78; 95% CI: 62-82) of samples.

The number of cattle available for follow-up varied for the months of October, November, December and February. There were only 16 cattle that were consistently negative and none was consistently positive for STEC O157 for the whole period. There was intermittent shedding of non-O157 STEC for the entire sampling event. There was a significant difference (P < 0.0001) between the proportion of non-O157 super shedders (92%) compared with the proportion of O157 super shedders. For the longitudinal study, the median STEC shedding level for non-O157 was 4.8log10 CFU/g, while the median for O157 was 3.4log10 CFU/g. Some cattle were consistent non-O157 STEC shedders throughout the 4-month period. Four cattle were super-shedders of non-O157 STEC persistently throughout the four sampling events and five were non-O157 super shedders for 3 consecutive sampling events. Four cattle were super shedders of both O157 and non-O157 STEC.

Only 8 animals were followed up at the abattoir primarily because of missing tags and sometimes due to the inability to keep up with fast processing lines. Overall, the prevalence of STEC based on the screening of carcass swabs using PCR was 32% (6/19; 95% CI: 13-57%), while STEC prevalence along the different stages of carcass processing was as follows: 22% (2/9), 17% (2/12), 25% (3/12) and 11% (2/19) for perineum hide, pre-evisceration, post-evisceration and post-wash swabs respectively (P = 0.688). There was no association between super shedding status (just before slaughter) and STEC carcass contamination for either O157 (P = 0.061) or non-O157 (P = 0.348). Likewise, there was no association between super shedding status (just before slaughter) and perineum hide swab STEC contamination for either O157 (P = 0.714) or non-O157 (P = 0.143) STEC.

The analysis of virulence genes and serotypes included isolates from the previous study together with this one. The distribution of virulence genes was highest in feedlot faecal samples (40%) compared with abattoir (33%) and retail outlets (28%) and this was highly statistically significant. Of the 86 STEC strains tested, the frequency of detection of stx1stxand a combination of both stx1and stx2 was 24%, 17% and 19% respectively. The eaeA gene was detected in 20 (23.3%) isolates in five different combinations; stx2+eaeA (2 isolates), stx1+stx2+eaeA (1 isolate), stx1+eaeA+hlyA (13 isolates), stx2+eaeA+hlyA (3 isolates), stx1+stx2+eaeA+hlyA (1 isolate). Of the 20 isolates carrying the eaeA gene, only two isolates (2/20; 10%) were found in mince beef, 3 isolates from abattoir carcass swabs (3/20;15%), and the remaining 15 isolates (15/20;75%) were found in feedlot cattle faeces. Of the 86 isolates recovered, only 39 could be serotyped, from which a wide range of serogroups (35) were detected.

On the pulsed field gel electrophoresis (PFGE) analysis, dendrograms of 55 isolates showed a high diversity with 45 distinct PFGE patterns. This diversity of PFGE patterns was observed in some isolates of the same serogroup that did not cluster together; these included serogroup O178 (feedlot environmental sample, feedlot cattle faeces, and supermarket boerewors). Also included were two isolates belonging to serogroup O20 (boerewors) and four serogroup O168 isolates (feedlot cattle faeces samples and abattoir perineum hide swab). Some patterns were observed in the dendrogram with varying band similarity percentages. At 100% banding similarity, eight band similarity patterns were identified. At 97.5% banding similarity, four closely related patterns were identified in eight isolates (7%): i. winter butchery boerewors and summer environmental feedlot faeces, ii. autumn supermarket boerewors and winter butchery boerewors, iii. summer cattle feedlot faeces and autumn butchery mince, iv. autumn brisket and mincemeat from the same supermarket. Analysis of the PFGE patterns at the 84.5% band similarity percentage or greater, revealed that most of the clades (7-clusters) belonged to isolates from different sources.

Conclusion

This study has established the presence of persistent and intermittent super-shedding of STEC O157 and non-O157 in cattle in a feedlot and at the abattoir just before slaughter. This results in continual environmental contamination and risk of re-circulation of the pathogen in the herds, which may lead to contamination along the food chain. In addition, the high count of non-O157, and the diversity of serogroups, shows that super-shedding is not limited solely to serogroup O157. We provide evidence of horizontal transmission and STEC strain recirculation along the beef production chain in Gauteng. All serogroups detected in this study have been previously implicated in STEC infections in human, with four considered as emerging serogroups. The high heterogeneity shown by PFGE and the difference in serogroups and virulence genes demonstrate the presence of a diverse but related STEC population in the beef production chain. There is need for further scientific investigation to advance the understanding of the dynamics of super-shedding in cattle, to sample a wider geographic region representing cattle-farming areas of South Africa, to conduct studies over a longer period to assess the impact of changes in climatic conditions and to promote epidemiologic surveillance for the clinically important STEC serogroups in public health laboratories in in South Africa.

POPULAR ARTICLE

Shiga toxin-producing Escherichia coli in beef cattle from feedlot through to abattoir

Dr LO Onyeka, Prof. AA Adesiyun, Dr KH Keddy, Prof. E Madoroba, Prof. PN Thompson

INTRODUCTION

Shiga toxin-producing Escherichia coli (STEC) has emerged as an important foodborne pathogen globally. Healthy colonized cattle are major reservoirs of this pathogen and cattle that shed STEC are considered to play a key role in the entry of the pathogen into the food chain. STEC causes a broad spectrum of disease from mild to intense bloody diarrhoea and in 5-10% of cases, haemolytic uremic syndrome (HUS). Globally Foodborne STEC have caused more than 1 million illnesses and 128 deaths. Of the over 470 different serotypes of STEC detected in humans, the O157:H7 serotype is the most frequently associated with large food and water-borne outbreaks. However, non-O157 STEC have been increasingly isolated from intermittent cases of haemorrhagic colitis and the sometimes fatal HUS.

The importance of the pathogen in South Africa and other southern African countries has recently been highlighted. STEC O157 was isolated in clinical stool specimens of diarrhoeic patients and environmental water samples in Gauteng, and recent reports from the Western Cape suggest STEC may be an environmental contaminant in informal settings and it is associated with diarrhoea in children under five years of age. Furthermore, in South Africa and other southern African countries, numerous clinical cases of diarrhoea in children and adults were reported between 2006-2013, in which a diverse range of STEC serogroups (O4, O5, O21, O26, O84, O111, O113, O117 and O157) were incriminated.

However, the poor surveillance and inadequate diagnostic techniques employed, almost certainly means that the occurrence of STEC-associated disease in humans is under-reported. Since the majority of beef consumed passes through the feedlot system, it is essential that we understand the dynamics of shedding of the organism in the feedlot and the characteristics of the pathogen in the beef production chain. This will help to identify control measures to reduce the bacterial challenge resulting in carcass and beef products contamination.

The present study aimed to determine the prevalence and dynamics associated with shedding of STEC in feedlot cattle and to characterise STEC isolates recovered at every stage along the beef production chain. The specific objectives were (i) to determine the frequency of shedders of STEC in cattle and associated animal factors in a feedlot in Gauteng Province through monthly sampling of a cohort of animals over a 4-month period; (ii) to longitudinally follow tagged study animals to slaughter and to determine the frequency of STEC contamination pre-slaughter, during slaughter and post-slaughter; (iii) to characterize STEC isolates with respect to their serotypes and presence of virulence; and (iv) to use pulse-field gel electrophoresis (PFGE) and serotyping to establish the genetic relatedness of the isolates between feedlot and abattoir.

MATERIALS AND METHODS

A six-month study from Sept 2016 to Feb 2017 was conducted at a commercial cattle feedlot located near Pretoria, Gauteng. The selected feedlot also owned a mechanized abattoir that slaughtered approximately 120 units per day. One hundred and six (106) cattle were randomly selected on arrival and tagged, and a minimum of 50 g of fresh rectal faecal grab sample was collected from each. Subsequently, over a period of 4 months, 26 cattle, including 15 animals identified as shedders and at least 11 non-shedders were selected, and sampled once a month until animals were sent for slaughter at the abattoir. At the abattoir, swab samples of tagged cattle were obtained from a 100 cm2 area using a sterile square metal template from each of four selected anatomical sites (4 x100 cm2 areas): rump, flank, brisket and neck, according to a standardized method.

Broth enrichment for processing of faecal samples was carried out and DNA Template from the broth enriched samples was investigated for the presence of stx1, stx2, eaeA and hlyA genes using multiplex PCR. 10-fold serial dilutions was plated on duplicate plates of two selective media known to target E coli O157 and non-O157 serogroups, incubated for 24 h at 37oC, after which typical colonies were selected and biochemically identified. Enumeration was performed by viable plate count method and expressed as CFU/g. Serotyping was conducted at the National Institute for Communicable Diseases (NICD). Pulsed-field gel electrophoresis (PFGE) of 55 isolates (including isolates from a recent study of beef products at retail outlets in Pretoria) was carried out to determine relatedness of strains.

RESULTS AND DISCUSSION

Samples collected on arrival at the feedlot indicated a STEC prevalence of 27% (29/106), with 19% and 11% being positive for stx2 and eaeA genes respectively. The longitudinal study showed that STEC non-O157 was shed at a significantly higher level than STEC O157. These results have several implications. Firstly, it demonstrates the presence of super shedding cattle in a feedlot herd. Secondly it shows that super-shedding is not limited to STEC O157, as described in recent reports from Europe. Thirdly, the higher prevalence of STEC non-O157 compared with O157 STEC is of public health significance, since non-O157 STEC have been increasingly linked to human disease in South Africa. Numerous clinical cases of diarrhoea in children and adults, as well as HUS, have been reported, in which a diverse range of STEC serogroups (O4, O5, O21, O26, O84, O111, O113, O117 and O157) was implicated.

It was also of interest that some cattle were simultaneous shedders of both STEC O157 and non-O157. In addition, several cattle shed ≥10,000 CFU/g non-O157 persistently throughout the study or for 3 consecutive sampling events. These cattle were identified as “super shedders”. Non-O157 STEC may be gaining importance in South Africa and such super shedders may pose an increased risk of contamination along the beef production chain, possibly leading to contamination of the food chain for human consumption.

PFGE has been used to track foodborne bacterial pathogens along the food production chain. In this study, PFGE analysis revealed a high diversity of 45 distinct PFGE patterns among 55 non-O157 STEC strains, which provides useful information on the genomic diversity of non-O157 STEC strains in the beef production chain in Gauteng. We observed eight PFGE-related patterns for 16 isolates originating from the same location and source but from different stages of the beef production chain, suggesting that the specific contaminating strain multiplied and spread at that point/stage of entry into the beef chain, such that once a pathogen is established at any production stage (farm, abattoir or retail processing) it may result in within-production-stage transmission. These data suggest evidence of epidemiological lineage, hence horizontal transmission of STEC strains along the beef production chain.

In this study, of the 86 STEC isolates only 17% carried the stx2 gene and 19% carried both stx1 and stx2. Of the virulence combinations, (23.3%) harboured the eaeA combinations. Epidemiologic studies have shown that the presence of stx2+eaeA gene combinations is important in the likelihood of developing HUS and with severe clinical symptoms. Of the 86 isolates recovered, only 39 isolates were serotypeable, from which a wide range of serogroups (35) were detected, including seven serovars of clinical relevance, namely O178, O174, O117, O101, O68, O8 and O2, considered to be emerging serogroups.

CONCLUSIONS

This study confirms that multiple different STEC strains are co-circulating in cattle in South Africa and further work needs to be done to establish whether these are clinically relevant in the human population. The high count of non-O157, and the diversity of serogroups, provides further evidence that super-shedding is not limited solely to serogroup O157. Also, we provide evidence of horizontal transmission and STEC strain recirculation along the beef production chain in Gauteng. There is need for active surveillance of STEC both in their reservoir host and in humans, and further studies to investigate effective methods to prevent contamination of the food chain.

Please contact the Primary Researcher on the project if you need a copy of the comprehensive report – peter.thompson@up.ac.za

Shiga toxin-producing Escherichia coli in beef

Prevalence and risk factors of Shiga toxin-producing Escherichia coli serotypes in beef at abattoirs and retail outlets in Gauteng

Industry Sector: Cattle and Small Stock

Research focus area: Red Meat Safety, Nutritional Value, Consumerism and Consumer Behaviour

Research Institute: Department of Production Animal Studies, University of Pretoria

Researcher: Prof. Peter Thompson Ph.D.

The Research Team

TitleInitialsSurnameQualification
ProfA.A.AdesiyunPh.D
DrE.MadorobaPh.D
DrL.O.OnyekaM.Sc

Year of completion : 2017

Aims of the project

  • To determine the prevalence O157 and non-O157 Shiga-toxin producing Escherichia coli (STEC) in beef abattoirs in Gauteng
  • To determine the prevalence O157 and non-O157 STEC in beef and beef products at retail outlets in Gauteng
  • To identify the important STEC serotypes present in beef and beef products in Gauteng
  • To identify risk factors for STEC contamination of carcasses and beef products in Gauteng

Executive Summary

Shiga toxin-producing Escherichia coli (STEC), particularly the O157 strains, are food-borne zoonotic pathogens of public health importance worldwide. Foods of cattle origin have been implicated in various outbreaks and epidemiological studies have revealed that cattle are major reservoirs of STEC. We conducted cross-sectional surveys from Nov 2015 to Nov 2016, to investigate the prevalence and molecular characteristics of O157 and non-O157 strains of STEC in beef and beef products in the Gauteng province of South Africa.

A total of 265 swab samples of beef carcasses from 12 abattoirs and 399 beef products from 31 retail outlets were screened for STEC using a multiplex PCR. The overall prevalence in abattoir samples was 37% (55/149) in summer and 34% (39/116) in winter. In beef products at retail outlets it was 20% (27/137) in autumn, 14% (18/130) in winter and 17% (22/132) in summer; the highest prevalence was detected in boerewors (35%) followed by mincemeat (21%). The predominant serotypes detected were O113 (19.4%) and O157 (14.9%) in beef products, and O113 (14%) from abattoirs.

Our results demonstrate that STEC is present in South African beef and beef products, and that this may pose a real food-borne disease threat. Further investigation of the epidemiology of the pathogen is required; it is proposed that this take the form of longitudinal studies to investigate the prevalence of shedding of STEC by cattle in the feedlot, following them through to the abattoir to determine factors associated with carcass contamination.

Additional Comments

As this is part of a PhD project, further molecular work is still to be done on the isolates, resulting in further planned publications. The samples also provided material for an MSc student (funded by UP research funds) to work on Salmonella contamination – these results will also be made available to RMRDSA once finalized.

Popular Article

Assessing the prevalence of shiga toxin-producing escherichia coli in beef at abattoirs and retail outlets in gauteng

Dr Lorinda Frylinck, Senior Navorser, LNR-Diere Produksie, Irene.

Introduction

The production of safe and wholesome beef and beef-derived food products is the highest priority for the beef industry in South Africa. There are potential risks associated with the possible presence of harmful pathogens in the food production chain; however, clear guidelines and regulations have been implemented to reduce these risks to a minimum and ensure a safe product for consumers. Nevertheless it remains important to continually assess these risks and to ensure effective implementation of control measures.

Shiga toxin-producing Escherichia coli (STEC) are bacteria associated with food and waterborne diseases and have been recognized as causing public health problems worldwide. The WHO Foodborne Disease Burden Epidemiology Reference Group (FERG) reported that ‘Foodborne STEC’ caused more than 1 million illnesses and 128 deaths in 2010 (8).

Of the over 470 different serotypes of STEC detected in humans, the O157:H7 serotype is the most frequently associated with large food and water-borne outbreaks (7). However, non-O157 STEC have been increasingly isolated from cases of haemorrhagic colitis (severe GIT infection and bloody diarrhoea) and as well as some fatal kidney failure (HUS; haemolytic uraemic syndrome) cases.

Although the first report of the occurrence of HUS in South Africa dated as far back as 1968 (6), the causative agent was poorly understood at that time. The first clinically proven incidence of E. coli O157:H7 in South Africa was later linked with haemorrhagic colitis (3). The importance of the pathogen in South Africa and other southern African countries has, however, been highlighted by subsequent major outbreaks of bloody diarrhoea in which E. coli O157 strains were implicated (4). Of particular interest was a study in Gauteng province in 2011, in which 7.7% of children with diarrhoea were positive for E. coli O157 (5).

Epidemiological investigations have revealed that cattle are a major reservoir of STEC. Many outbreaks of E. coli O157:H7 have been associated with beef, in particular ground beef, and analyses of some cases have identified undercooked beef as a significant risk factor. However, the fact that E. coli-associated conditions in humans, such as HUS, are not as yet notifiable in South Africa may mean that the occurrence of STEC-associated disease in humans is under-reported. In addition, given the weight of evidence from elsewhere in the world, it is possible that contamination of beef products is also a risk factor in South Africa.

Research problem and objectives

There is a dearth of current information on the frequency of occurrence of O157 and non-O157 strains of STEC, and on the risk they pose to consumers of beef products, in South Africa. Hence, the objective of this study was to determine the prevalence and characteristics of O157 and non-O157 STEC strains in beef carcass and beef products sold at retail outlets in the Gauteng province of South Africa.

Materials and Methods

During a one-year period from Nov 2015 to Nov 2016, two independent cross-sectional surveys were carried out to determine the prevalence of STEC at abattoirs as well as at retail outlets where beef-based food products are sold.

Study 1: Twelve abattoirs (six high throughput and six low throughput) were selected and each was visited during summer and winter months for sample collection. Five animals were randomly selected in each abattoir and tagged for sample collection. Firstly, samples were collected by swabbing the skin of the perineal area immediately after slaughter. Thereafter, carcass swab samples were collected from different parts of the carcass at various stages during processing, including pre-evisceration, post-evisceration, post-washing and 24 hours post-chilling.

Beef carcass sampling and processing at the abattoir

Study 2: A total of 31 retail outlets including both large supermarket chains and smaller butcheries were randomly selected. Visits were made to each of these outlets during autumn, winter and summer months of 2016 for sample collection. Sampling of five types of popular beef products (brisket, boerewors, mince, cold meat, and biltong) was done at each outlet during each visit.

Each sample was analyzed for the presence of Shiga toxin-encoding genes (stx1and stx2) using conventional multiplex PCR. All samples positive for stx genes based on PCR were screened for the following O-serotypes: O26, O91, O103, O111, O113, O145 and O157 using a multiplex PCR assay.

Results and Discussion

Overall, the prevalence of STEC in beef carcass swabs collected from 12 red meat abattoirs across Gauteng province during summer and winter months was 35.5% (94/265). The highest prevalence (50%) was detected in perineal samples, which is hardly a surprise because cattle are an established reservoir of STEC; this may therefore reflect the prevalence of the pathogen in cattle arriving at abattoirs. Transportation stress is known to increase the shedding of enteric pathogens and could therefore be a contributing factor to the observed high prevalence in perineal samples. STEC was found in 39% of both pre-evisceration and post-evisceration carcasses, while washed carcasses and 24 hour chilled carcasses had a lower prevalence of 23% and 20% respectively. Therefore, although washing of carcasses at the abattoir removed much of the STEC contamination, the fact that the bacteria were still present on the surface of some chilled carcasses is of potential food safety significance, since cuts from these carcasses end up for sale in various forms at retail outlets.

Boerewors on display in a retail outlet

Of the 399 beef products sampled from 31 retail outlets, 67 (16.8%) were contaminated by STEC strains, an observation that is of food safety significance if such products were to be improperly cooked and consumed by highly susceptible individuals.

The highest prevalence of STEC was detected in boerewors (35%), followed by minced meat (21%). Ground beef ordinarily includes meat from many carcasses; consequently a few infected livestock could potentially contaminate a great quantity of ground beef. Biltong had the lowest prevalence of contamination (5%), while brisket and cold meat had 11% and 6% respectively. These results are in contrast to a previous study in South Africa, in 2009, involving biltong, cold meat and minced meat at retail outlets, which found that 2.8% of the samples were positive for E. coli O157 (1).

The prevalence of STEC in abattoir and retail outlet samples was somewhat higher during the summer months compared to the winter months. While many factors are believed to affect the prevalence of E. coli O157:H7, only season has been consistently shown to impact the shedding of this bacterium by cattle (2), and some previous studies have also observed a higher prevalence of shedding during the warmer months than the winter months.

The serotype analysis showed that O113 was the post prevalent serotype both on beef carcasses (14%) as well as in beef-based products (19%). This observation is of particular interest considering that O113 is an emerging serotype associated with human illness and sometimes with HUS in several countries including Spain, Belgium and Australia. Serotype O113 of STEC may therefore potentially be important in human diseases in South Africa and this requires further studies. Some of the other serotypes detected  have also previously been implicated in human diseases elsewhere in the world.

Unlike in abattoir samples where the prevalence of serotype O157 was very low (1%), a higher prevalence of 15% was detected in retail meat samples. This finding may be explained in part by the fact that the current study was cross-sectional by design (giving a “snapshot” at a particular point in time) and not a longitudinal study. Therefore serotype O157-contaminated beef products may have originated from abattoirs not sampled in the current study, and the prevalence may vary greatly between places and over time. There is also a possibility that it may partially also be a result of contamination from other sources at the retail outlet level.

Mince meat on display in a retail outlet

Conclusion

This study has shown that contamination of beef products with potentially harmful bacteria can occur during different processing stages. The low numbers of reported cases of food-associated disease in South Africa suggest that the risk to consumers is low; however, it is not known whether all cases are reported, or that all cases are correctly diagnosed. Therefore, further research is needed in order better understand the dynamics of foodborne pathogens in South Africa, to accurately assess the risk they pose, and to accurately inform control measures.

It is well known that efficient implementation of control measures during slaughter and processing procedures can greatly reduce meat surface microbial contamination and ensure the safety of the final product. The South African Meat Safety Act (2000) has addressed potential risk factors by adopting several internationally recognized preventive measures such as the Hazard Analysis Critical Control Point (HACCP) system and Good Manufacturing Practices (GMP) in order to promote safe meat for consumers. The application of GMP and HACCP principles during handling and processing of products, as well as the proper cooking of meat products before consumption, will effectively reduce the threat of food borne disease.

Acknowledgments

We thank Red Meat Research and Development South Africa (RMRD SA) for funding this research and the Gauteng Department of Agriculture and Rural Development for granting us access and assistance to carry out the cross-sectional survey at the abattoirs.

References

  1. Abong’o, B.O. and Momba, M.N., 2009. Prevalence and characterization of Escherichia coli O157: H7 isolates from meat and meat products sold in Amathole District, Eastern Cape Province of South Africa. Food Microbiology, 26(2), pp.173-176.
  2. Berry, E.D. and Wells, J.E., 2010. Escherichia coli O157: H7: recent advances in research on occurrence, transmission, and control in cattle and the production environment. Advances in Food and Nutrition Research, 60, pp.67-117.
  3. Browning, N.G., Botha, J.R., Sacho, H. and Moore, P.J., 1990. Escherichia coli O157: H7 haemorrhagic colitis. Report of the first South African case. South African Journal of Surgery, 28(1), pp.28-29.
  4. Effler, E., Isaäcson, M., Arntzen, L., Heenan, R., Canter, P., Barrett, T., Lee, L., Mambo, C., Levine, W., Zaidi, A. and Griffin, P.M., 2001. Factors contributing to the emergence of Escherichia coli O157 in Africa. Emerging Infectious Diseases, 7(5), p.812.
  5. Galane, P.M. and Le Roux, M., 2001. Molecular epidemiology of Escherichia coli isolated from young South African children with diarrhoeal diseases. Journal of Health, Population and Nutrition, 19(1), pp.31-38.
  6. Kiibel, P.J., 1968. The haemolytic-uraemia syndrome: a survey in Southern Africa. South African Medical Journal, 42(27), pp.692-698.
  7. Mora, A., Herrera, A., López, C., Dahbi, G., Mamani, R., Pita, J.M., Alonso, M.P., Llovo, J., Bernárdez, M.I., Blanco, J.E. and Blanco, M., 2011. Characteristics of the Shiga-toxin-producing enteroaggregative Escherichia coli O104: H4 German outbreak strain and of STEC strains isolated in Spain. International Microbiology, 14(3), pp.121-141.
  8. WHO [World Health Organization], 2015. WHO estimates of the global burden of foodborne diseases. Available at http://apps.who.int/iris/bitstream/10665/199350/1/9789241565165_eng.pdf

Please contact the Primary Researcher if you need a copy of the comprehensive report of this project – Peter Thompson onpeter.thompson@up.ac.za