Stress Responses in Pathogenic Yersinia enterocolitica with Reference to the Stability of the Virulence Plasmid in Food (pp. 583-591)
Authors: (Saumya Bhaduri, and James L. Smith. Agricultural Research Service, Eastern Regional Research Center, Wyndmoor, PA, USA)
Abstract: Yersinia enterocolitica has been associated with foodborne illness, most often due the ingestion of pork products. The pathogenic effects induced by a Y. enterocolitica infection are caused by the interplay of chromosomal genes and a virulence plasmid, pYV. Generally, the plasmid is lost during growth of the organism at >32˚ C, resulting in avirulence. Prior exposure of Y. enterocolitica to sublethal temperatures (heat-shocking) leads to cells that are resistant to subsequent exposure at higher temperatures. Exposure of heat-shocked cells to 55˚C did not result in loss of pYV. There was no loss of pYV induced by freezing during storage, and freezing had no effect on enrichment and isolation of Y. enterocolitica. Growth of Y. enterocoliltica under vacuum or in atmospheres containing CO2 at 28˚C did not lead to plasmid loss. Y. enterocolitica can grow at pH values ≥ 4.4 but the effect of acidification on the stability of the virulence plasmid is not known. Stressful conditions do not necessarily lead to the loss of pYV, and a food product containing the stressed pathogen may be capable of inducing food poisoning.