​​​Postdoctoral Fellows

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Dr Michaela van den Honert

Antibiotic resistant bacteria prevalent in livestock and wildlife species in South Africa​

Much research has focused on the fate of antibiotics in clinical settings whereas research of antibiotics in natural environments has been comparatively limited. Conducted within the newly established Centre for Food Safety at Stellenbosch University, the research will determine the prevalence of antibiotic resistant bacteria in food-producing livestock and game species in South Africa. This research strives to make a contribution to a greater global understanding of how resistance to antibiotics may increase in future through highlighting key agricultural sources and distribution patterns of the spread of antibiotic resistant bacteria in food-producing livestock and game. Research in this field will focus on antibiotic resistance involved with animal feed, in game and livestock species under various different farming practices, in the food production environment under different processing conditions as well as looking into alternatives to antibiotics. ​​

​​PhD Students

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Anneri Carinus​​

Listeria monocytogenes attachment, survival and internalisation into cantaloupe

Fresh produce outbreaks have been increasing over the years, with the largest and deadliest global outbreak to date being attributed to whole cantaloupe contaminated with L. monocytogenes.  Although cut cantaloupe have mostly been implicated in outbreaks due to contamination occurring during preparation, contamination of whole cantaloupe is particularly of concern.  The surface of cantaloupe provides an ideal environment for microbial attachment and could easily be introduced into the flesh upon cutting. However, a large possibility also exist that harmful pathogens have the ability to internalise, especially during the washing step during post-harvest processing.  Once internalised the pathogen is protected from various environmental factors, have access to enough nutrients and moisture which could lead to the pathogen proliferating to high and dangerous levels.  The behaviour of L. monocytogenes on the cantaloupe rind and possible internalisation as well as factors such as serotype, environmental conditions and gene expression facilitating its behaviour requires extensive research.  Moreover, L. monocytogenes has been shown to enter the Viable but Non Culturable state, which is cause for concern as it could result in the pathogen being undetected while maintaining virulence.

The aim of this study will be to investigate the ability of L. monocytogenes strains to attach, survive and internalise into whole fruits such as cantaloupe with special emphasis on the impact of storage temperatures, the ability to enter a VBNC state on the rind and the genes involved facilitating its behaviour.​

​MSc Students

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Samanth​a du Toit
​Listeria monocytogenes in ready-to-eat (RTE) fresh produce and hummus, and the food processing environment: characterisation and analysis using Whole Genome Sequencing (WGS)

In short, this study involves the genetic analysis of L. monocytogenes from RTE fresh produce and hummus, and the food processing environment using mainly WGS and bioinformatic tools. It creates epidemiological surveillance data for the Western Cape, South Africa for the years 2018 to 2021 by investigating the distribution of lineage types, serotypes and sequence types in the outlined origins of interest, and by identifying trends between these sub-groups, virulence and antibiotic resistance.

The history of listeriosis in South Africa suggests dissemination of the foodborne pathogen in foods and the production environment. The high fatality rate of the invasive disease and the large population of vulnerable people in our country is concerning. To reduce the burden of foodborne illness, it is important to consider these novel foods as potential sources of contamination and infection, and to better understand the risk associated with them in South Africa. Lack of vigilance will have serious consequences to public health and the economy. 

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Corani Jankowitz​

​​Photoreactivation of food pathogens from UV​ treated river water in the Western Cape

Microbiologically contaminated river water used for irrigation of fresh produce can lead to foodborne pathogens being transferred to humans which can cause severe illness. Decreasing the initial microbial load of the water used for irrigation will make subsequent food safety steps from farm to fork more effective. UV treatment has been proven to be an effective and economical solution to make river water safer for irrigation purposes. There is however a natural defence mechanism present in microbial cells to repair UV damage due to it being a natural envir​onmental stressor. One of​ these mechanisms is known as photoreactivation, which is light dependant and utilises the photolyase enzyme. The aim of this research is to thoroughly investigate photoreactivation, specifically on foodborne pathogens, in order to make recommendations for the use of UV irradiation at farm level to disinfect irrigation water for improve​d food safety of fresh produce.​

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Jesse Kelfkens
​Investigation and elimination of mould found in pasteurised based baby food pouches

A given company has been receiving several customer complaints regarding some of their baby food squeeze pouches. The complaints describe a green, viscous mould present within some of the pouches which gives the contents an unappealing colour, flavour and odour. Not only does this mould make the product undesirable, but it is also perceived to be hazardous by the customer especially with such a delicate consumer. Upon investigation it has been indicated that this problem is a global issue, extending well beyond the given company's product.

This research will investigate the prevalence of the mould present within these pouches. Furthermore, this research strives to make a contribution to a greater global understanding of how this mould is able to occur within this product and what measures could be possibly implemented to eliminate its presence.​






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Liné​ Becker
​Investigating the influence of various food safety practices, linked to microbial incidences detected within a retail chain store's deli department

There is global concern with regards to foodborne diseases as the World Health Organisation has reported that almost 1 in 10 people in the world fall ill after eating contaminated food and 420 000 die every year.  Amongst the different food types, ready-to-eat foods can be classified as opportunistic vehicles for pathogenic bacteria. Thus, a comprehensive study of the current practices within the retail chain stores is necessary. 

The food safety knowledge, practice, and training of food handlers in deli departments will be examined to investigate the influence that these various food safety indicators have on the microbial incidences detected within a retail chain store. The research will also identify high-risk environments, by taking swabs, doing product storage investigations, and evaluating the current Food Safety Management System and compliance to it. 

With this research I would like to identify potential routes for cross-contamination between foodborne pathogens and ready-to-eat foods in specific retail chain stores, to identify and improve knowledge gaps amongst food handlers, to make recommendations to prevent contamination and the growth/survival of microorganisms, and to better understand how pathogens may be transferred as a result of supply chain practices and handlings systems. ​

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Marco Oosthuizen​

Ultra-violet (UV) treatment of irrigation water at farm level to reduce microbial contamination for improved food safety

The microbiological quality of South African rivers has become a cause for concern. Insufficient sanitation facilities and inadequate sewage treatment works throughout South Africa have often been implicated as the primary source of pollution. Farmers are often dependent on these rivers as their only source of irrigation water, and thus their use poses a possible health risk to farm workers and consumers alike. Prevention of river and irrigation water pollution would be the ultimate solution, but in the interim cost-effective treatment techniques for irrigation water are required to ensure food safety.

The aim of this project is to conduct a study on the technical and ​financial requirements for an on-farm UV irrigation water treatment system to reduce microbial contamination for improved food safety.​








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Taish Ramkisson​

Reviewing the dissemination of carbapenemase-pr​oducing Enterobacteriaceae within the agricultural setting of Western Cape, South Africa

The rapid emergence of antibiotic resistance poses a great threat to human health worldwide, resulting in an estimated 700 000 deaths each year. African reviews suggest that there are trends of multiple resistance towards commonly used antibiotics. However, due to insufficient antibiotic resistance surveillance, there is a lack of accurate and reliable information regarding the true extent of the antibiotic resistance crisis in Africa.Carbapenems are a class of beta-lactam antibiotic agents which have a broad spectrum of bactericidal activity against various pathogens. 

This will be the first study to determine the presence of carbapenemase-producing Enterobacteriaceae in the agricultural setting of the Western Cape, South Africa. Outcomes include identifying a possible link of carbapenemase-producing Enterobacteriaceae between the clinical and agricultural setting, identifying which genes are associated with carbapenem resistance in the agricultural setting and to identify whether these genes are the same as those occurring worldwide.

The relevance of the results from this study will allow to fill the large gap in literature regarding the dissemination of carbapenem resistant organisms in the South African food and agricultural setting, as well as contribute positively towards the goal of the 'One Health' concept within South Africa. Furthermore, information generated from these results can be useful for advising farmers about possible risks and risk control with regards to the bacterial antibiotic resistance phenomenon.

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Kyle Corbett

​The effect of sanitiser technologies on the growth of biofilm and non-biofilm Listeria monocytogenes

Listeria monocytogenes is a pathogen which causes the human disease, listeriosis, which can result in death. The ubiquitous nature of the organism throughout nature means it can also be found in food processing facilities.  

This organism can also persist in food processing facilities due to the fact that it can grow at refrigerated temperatures and form biofilms on stainless steel equipment.  Listeria monocytogenes has developed certain resistance mechanisms to commonly used sanitisers that are used in factory cleaning. My job is to develop an optimal treatment regime for the food industry against L. monocytogenes which show resistance to certain sanitisers in both the biofilm (sessile) and non-biofilm (planktonic) state.  My research will result in a better understanding of factory cleaning and optimised regimes for sanitiser applications, which will ultimately result in safer food production.​​​

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Michael 
Esterhuysen

The investigation of Listeria spp. in the South African ready-to-eat processed fruit supply chain

Fresh-cut tropical fruits, an important source of carbohydrates, vitamins, minerals and fibers, are particularly attractive to consumers all over the world. This is seen in the growing demand for processed fruit products, however their association with foodborne pathogens, particularly Listeria monocytogenes, has become a growing concern. In order to effectively manage the prevalence of Listeria monocytogenes within the processed fruit supply chain, a holistic investigation of all Listeria species present from growers to processors will be of significant value.

This research project focuses on papaya and cantaloupe and aims to gain insight into the ecology and distribution of Listeria spp. in the processed fruit environment, to investigate any changes in the distribution of Listeria species throughout the food supply chain and to identify the po​ints where intervention is required to ensure food safety.​




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Caitlin McQuillan  ​

Listeria, Campylobacter, Salmonella, Escherichia coli and shiga toxin producing Escherichia coli in pork

Foodborne pathogens in pork is currently a major global issue with their presence being a major contributor to human illnesses, hospitalisations and fatalities each year. There is an increased struggle to control the presence of these foodborne pathogens during pork production, thus a vast and comprehensive understanding of these pathogens as well as their respective sources is required in order for the industry to develop and implement effective food safety interventions for pork production.

This study aims to determine the presence, prevalence and respective sources of Salmonella spp., Campylobacter spp., Listeria spp., Escherichia coli and STEC, as well as the high risk areas in the pork production chain in order to limit and control the contamination during the production from farm to shelf.​


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