Yersinia pathogenesis, colon, clinical findings, diagnosis, treatment

1. Yersinia in
colon

2. Y. enterocolitica & Y. pseudotuberculosis
 Gr-
 Urease positive
 Oxidase negative
 Grow best at 25 *C and are motile, non-motile at 37 *C
 Y. enterocolitica has 70 serotypes
 From rodents and domestic animals to humans by food
and drink contamination
 Y. pseudotuberculosis has 6 serotypes (O:1)
 From domestic and farm animals to humans by ingestion
of material contaminated with feces

3. Pathogenesis
 108-109 must enter the human to make infection
 IP 4-7 days
 Multiply in the gut and ileum
 Leads to inflammation and ulceration
 Leukocytes appear in feces
 May extend to mesenteric lymph nodes, and rarely
bacteremia

4. Clinical findings
 Early symptoms: fever, abdominal pain and diarrhea
 Diarrhea ranges from watery to bloody, may be caused
by enterotoxin
 The pain may sometimes indicate appendicitis
 Late (1-2 weeks): Patients with histocompability complex
HLA-B 27 develop arthralgia, arthritis and erythema
nodoum (picture)
 Rarely: pneumonia, meningitis, sepsis

5. Diagnosis
 Specimens: in stool, blood
 Culture: “cold enrichment” is used to increase the amount
of fecal organisms. Small amount of feces or rectal swab is
placed in buffer saline with pH 7,6 and kept at 4 *C for 2-4
weeks. Many organisms do not survive, but Y.
enterocolitica multiplies
 MacConkey agar may yield yersiniae

6.  CIN agar at room temp. for several days: colonies with
bull’s eye appearance with a red center (picture)
 Serology: not useful due to cross-reactions between
Yersinia and other organisms

7. Treatment
 Mostly self-limited diarrhea
 Y. enterocolitica is susceptible to many antibiotics, but
resistant to ampicillin and first-generation cephalosporin
 Prevention of further infections: better hygiene routines
with food and diary products packing

8. Sources
 http://www.bacteriainphotos.com/yersinia_on
_cin.html
 Medical microbiology by Jawetz, Melnick
and Adelberg’s