Detection of pathogenic Yersinia in foods
ESR is leading a research project to improve Yersinia laboratory methods so that potential food sources or reservoirs harbouring Yersinia can be identified. Information from this research will help agencies such as New Zealand's Ministry of Primary Industries (MPI) devise strategies to reduce these pathogens in the food chain and thus decrease human disease in New Zealand.
Rates of yersiniosis are high in New Zealand compared to other developed countries and the majority of human cases are considered sporadic and without an identifiable source. Foodborne transmission is the most likely route of infection but baseline data on Yersinia from foods and the environment is lacking and thus the epidemiology of Yersinia remains unclear. Surveillance has also observed a marked increase in the number of human cases involving the Yersinia enterocolitica biotype 1A, a biotype that is often referred to as ‘non-pathogenic’ in other countries due to their lack of virulence factors such as the pYV plasmid commonly found in other biotypes.
New culture independent diagnostic tests (CIDTs) being implemented in laboratories may further cloud issues as many tests target recognised genes associated with pathogenic biotypes that are normally lacking in the biotype 1A group. As a result, biotype IA strains present in a sample may be ‘missed’ when these types of tests are used. Further difficulties lie in the isolation of Yersinia from foods using traditional culture methodology. Although international standard methods for the detection and isolation of Y. enterocolitica and Y. pseudotuberculosis from foods exists, isolation rates are low and the methods are long making the test of little utility in outbreak investigations and hinders the accurate identification of reservoirs/sources.
MPI has partnered with ESR to elucidate putative genes that can distinguish between pathogenic and non-pathogenic Y. enterocolitica with an aim of including appropriate gene targets in a molecular detection assay. The targets will be used in combination with an improved isolation method which is also being investigated.