What Is Yersinia Pastis?

From Bacillus to Coccus, the diameter ranges from 0.5 to 0.8 m and the length ranges from 1 to 3 m. No spores. No capsule was formed, but Y. pestis (Y. pestis) was able to produce a coating in cells grown at 37 ° C or from in vivo samples. Gram negative. Do not exercise at 37 ° C. When growing below 30 ° C, it moves with pericyate flagella.

Yersinia

Yersinia pestis never moves. Grow on ordinary nutrient media. After 24 hours of culture on nutrient agar, the colonies were translucent to opaque, with a diameter of 0.1 to 1.0 mm. The optimum growth temperature is 28 29 . Facultative anaerobic, has both respiratory and fermentation metabolism. Oxidase is negative and contact enzyme is positive. Except for individual biovars, it can reduce nitrate to

Yersinia pestis

The pathogen of plague. Most of them are scattered in pure culture and can be arranged in double in the host body fluid. It was highly polarized in newly isolated strains and animal body fluids. It is obviously polymorphic in chronic lesions, stale cultures or 3 to 4% salt agar medium, and spherical, rod-shaped, yeast-shaped, and dumbbell-shaped shapes of various sizes are visible. It forms a capsule-like surface mucus layer in the host, which has anti-phagocytosis. The best growth temperature is 25 30 . The suitable pH is 6.9 ~ 7.2. After 48 hours of incubation on ordinary media, colorless, transparent, small, round, and rough colonies grew thick and dense in the center, thin in the periphery, and irregular edges. After 48 hours in the broth medium, a bacterial film was formed, and the viscous cotton floc growth was suspended under the bacterial film. This feature has identification value. Antigen composition is complex, with more than 20 species. Among them, V, W, and envelope component I are related to virulence. This bacterium contains at least endo-toxin and murinetoxin. Plague is often prevalent in rodents before it becomes epidemic. Rat flea bites the crowd after losing its host. Human plague has glandular, septic, and lung types. Human plague can cause human-to-human transmission through human fleas or the respiratory tract (lung type). Can be prevented with attenuated live vaccines. Treated with streptomycin, sulfa drugs.

Yersinia pseudotuberculosis

Biological characteristics are similar to those of Y. pestis. The difference is that the bacteria have power at 18 22 and can still grow at 4 . Decompose urea, ferment rhamnose, and grow into large, opaque colonies on deoxycholate-citrate agar medium. According to the bacterial body and flagella antigen, it can be divided into at least 6 serotypes. It mainly causes rodent diseases, and guinea pigs are particularly susceptible. Lesions are caseous swellings and nodules that resemble tuberculosis in various organs of infected animals. The natural route of transmission may be the digestive tract. Human infections have occasionally been reported, and diseased rabbits may be the source of infection. Humans are mostly symptomatic of intestinal infections with mesenteric lymphadenitis, like acute appendicitis.

Yersinia enterocolitica

Similar to Pseudotuberculosis, flagella are formed at 22 ° C and can move. The difference is that esculin, rhamnose or salicin are not fermented, but sucrose is fermented. There are at least 34 serotypes and 5 biotypes. This fungus is highly pathogenic to animals such as chipmunk, pigs, and cattle. Humans also have sporadic infections that cause acute gastroenteritis. The source of infection is sick animals, and possibly contaminated water.