Yersinia sp.

Characteristics of Yersinia Enterobacteriaceae family Morphology, growth characteristics, non-spore forming Motile? Well, yes and no ~100,000 cases (7th)

Taxonomy and classification 11 species Four pathogens Y. pestis Y. pseudotuberculosis Y. ruckeri Y. enterocolitica Serotyping O:3, O:9, O:5,27 H-typing exists (a,b; b,c; b,c,e,f,k; etc) but is seldom done

Biotyping

Growth characteristics Psychrotroph -1 oC to 40 oC Heat sensitive D62.8C in whole milk ~1-60 seconds Slightly more salt resistant Grows in 5% salt pH ~4.0-10; optimum 7.6

Reservoirs Zoonoses Large number of wild and domestic animals Wild rodents Freshwater ecosystems, soil, rivers, particularly in cool weather Distribution of specific biotypes/serotypes Pigs, especially tonsils (biotype 4, also biotype 2) Wild rodents (?) (biotype 1B; O:8 and O:13a,13b) Foods of concern: undercooked pork, chitterlings Animal pathogenic strains exist but are different

https://www.cdc.gov/yersinia/chitlins.html

Outbreaks Location Year # cases Serotype Source New York 1981 159 O:8 Powdered milk/chow mein Southern US 1982 172 O13a,13b Pasteurized milk Chicago 2002 9 O:3 Chitterlings Norway 2005 11 O:5,27 Brawn 2011 21 O:9 Salad mix PA 7 Not reported Finland 2014 43 O:1 Raw milk

Disease About 104 cfu necessary 3-7 day incubation period Diarrhea, fever, abdominal pain Few days to three weeks Acute mesenteric lymphadenitis, presents as pseudoappendicular syndrome In rare cases, may have immunological complications Reactive arthritis Typically less than three months, prognosis good

Take-home points Y. enterocolitica is species of most concern to food microbiologists Primary sources are pigs, and possibly rodents; reservoir depends upon serotype Psychrotrophic Not terribly resistant to inactivation Unique disease Unique phenotypes