Yersinia Enterocolitica is a facultatively anaerobic, gram-negative bacillus-shaped bacterium, that’s motile at 22–29°C and nonmotile at normal human body temperature (37°C), belonging to the family Enterobacteriaceae. This organism was first found by Schleifstein and Coleman in 1939 as “an unidentified microorganism resembling Bacterium lignieri and Pasteurella pseudotuberculosis, and pathogenic for man.” Figure 1 shows the model of Y. Enterocolitica.
Characteristics of Yersinia Enterocolitica
Colonies of Y. Enterocolitica don’t ferment lactose on mediums containing bile salts, and typicl strains give positive reactions in Christensen’s urea agar and negative reactions for citrate use.
Yersinia Enterocolitica produces an acid butt and an acid slant on triple-sugar iron agar without hydrogen sulfide, but little or no gas. Now, this species can be characterized by biochemical testing, serotyping, phage typing and plasmid analysis. Figure 2 shows colonies’ characteristics of Yersinia Enterocolitica:
Yersinia Enterocolitica includes 11 species: Y. pestis, Y. kristensenii, Y. pseudotuberculosis, Y. enterocolitica, Y. mollaretii, Y. frederiksenii, Y. intermedia, Y. aldovae, Y. bercovieri, Y. rohdei and Y. ruckeri. Yersinia Enterocolitica has been found in human from many countries in the world, but it seems this organism has been found most frequently in cooler climates. This means that this genus often outbreaks during the fall and winter. According to different principles, Y. enterocolitica has been divided into six biogroups based on phenotypic characteristics by biotyping method, and more than 57 O serogroups based on their O surface antigen by serotyping method. Five of the six serogroups, 1B and 2-5, are considered as pathogens, however, among these serogroups, only a few of them have been associated with disease in animals or human beings. Geographic differences result from distribution of Yersinia Enterocolitica and thus related diseases outbreak. Even though strains come from serogroup O:3, O:5, O:8, O:9 and O:27 are most frequently isolated from human samples, the O:3 serotype is the most frequently found in European countries.
Fig. 2 Colonies’ Characteristics of Yersinia Enterocolitica
The clinical illness caused by this pathogen ranges from self-limited enterocolitis to potentially fatal systemic infection; post-infection manifestations include erythema nodosum and reactive arthritis.