Our Research
For many years we have been working on various detection methods for common and emergent foodborne pathogens such as Campylobacter, Salmonella, Listeria and more recently Cronobacter (Enterobacter) sakazakii, ranging from chromogenic agars, immunomagnetic separation and also hygiene assessment via ATP swab techniques. Our studies range from food hygiene and HACCP implementation in industry, through detection methods, to genetic manipulation of common pathogens, and virulence studies with mammalian cells cultures. Look at the publications to see some of the outputs from our work.
Methods Development
The gold standard for so many detection methods remains the agar plate. Our work has helped develop a number of agars and broths for use within industry. Currently our emphasis is on chromogenic agars because of their potential for discriminating target organisms within a mixed flora on an agar surface. We also helped develop and validate the immunomagnetic separation techniques for Salmonella and Listeria, as well as improvements for the ATP swabs which overcome the problems of detergent residues. Genotyping is used to ensure a diverse range of well characterised strains is used in all method developments
Cronobacter (Enterobacter) sakazakii
This is an emergent pathogen that is associated with infant infections including necrotising enterocolitis, bacteraemia and even meningitis. To date the recognised source is through the ingestion of rehydrated infant formula milk powder. Whether the contaminaton is during processing or rehydration is still to be fully determined. We have already developed a chromogenic agar (Int. J. Food Microbiol. 96, 133-9) that is being marketed by Oxoid Ltd UK (Druggan-Forsythe-Iversen agar, CM1055). We are also working on the virulence of the organism, improved isolation methods and phylogenetic relationships. The 16S & hsp60 sequencing has shown that isolates identified by commonly used biochemical kits are more than one species (see paper in J Clin. Microbiol. 42, 5368-70). Prof Forsythe was participant and both FAO-WHO workshops February 2004 (Geneva) and January 2006 (Rome). The team has thirteen papers published on the subject, including a risk profile in Trends in Food Science and Technology 11, 443-54. The article in Maternal and Child Nutrition 1, 44-50 was voted paper of the month by Unicef. They have also published the most detailed account of a neonatal intensive care unit outbreak. It should be noted that not all strains of C. (E.) sakazakii produce a yellow pigment and therefore will be missed using the recommended FDA method. See 'Publications' for a full listing of papers, and conference presentations.
Campylobacter and Related Organisms
Campylobacter jejuni is recognised as the major cause of foodborne bacterial gastroenteritis. Yet its virulence mechanisms are still poorly understood. Using knock out mutants we have been studying particular genes involved in host cell damage.
Arcobacter butzleri and related species are emergent pathogens. A. butzleri is a recognised veterinary pathogen, and is found in the food chain. There have been a few human cases of gastroenteritis due to the is organism, but clear epidemiological eveidence is still sparse. Regretfully this is partly due to the lack of general awareness and use of appropriate selective media. We are working in conjunction with University of Northampton, on the virulence and persistence of the organism.
Food Surveys
The presence of foodborne pathogens in the food chain is very important in microbial risk assessment. We have undertaken a number of surveys for particular pathogens which serve the dual purpose of assessing the organisms' presence in foods, and also determining the efficacy of novel detection methods being developed. Linked to this are the studies into food hygiene and HACCP implementation in the food industry, particularly small companies. These have largely been published in refereed journals, though further work has been undertaken on consultancy basis.
Other work
We have used bacteriophage as indicators of possible enteroviruses and there removal during water purification. Overall they are potentially very indicative of the possible presence of Noroviruses (formerly small round structured viruses, or Norwalk-like viruses) which cannot be grown using current tissue culture methods.
