PhD Supervisors  Prof I Blair & Prof. D McDowell

Dr Catherine M. Logue

This study examined a number of different aspects of the foodborne pathogen Yersinia enterocolitica.  A retail survey of the incidence of this organism on meat determined that this organism was relatively prevalent, although the incidence of pathogenic strains associated with human illness was rare.  Y. enterocolitica serotypes O:3 and O:5,27 were the most common pathogenic strains isolated.  Most samples tested had initial numbers less than 2.7 log10cfu/g, and further studies examined the use of a number of enrichment broths to increase the numbers of the organism present to concentrations that could be detected by any developed rapid method.  The study found that plasmid bearing pathogenic and plasmid cured strains behaved differently in enrichment media and were also influenced by the enrichment temperature used.  Other studies also examined the growth of pathogenic and non-pathogenic Y. enterocolitica strains on three different meat species stored at 0, 5 and 10ºC, to determine the influence the meat species, and its associated microflora, as well as storage temperature on the growth of these strains.  Results showed that both pathogenic and non-pathogenic strains behaved similarly on all meat species examined and significant growth was observed at all three storage temperatures.  These studies showed Yersinia competed relatively well with the natural spoilage flora of the meat when present at relatively low numbers.  The final phase of this study examined the development of a rapid method for the isolation of Y. enterocolitica serotype O:3 from enriched meat samples using a surface adhesion immunofluorescent staining (SAIF) technique.  Results obtained showed good linear relationships between the numbers of Yersinia in the enrichment culture and the numbers detected by SAIF, using spiked samples.  Similar results were also obtained with spiked commercial samples.