Yersinia pseudotuberculosis is a gram-negative bacterium that can cause pseudotuberculosis in humans. It is commonly transmitted through contaminated food and water. Symptoms include abdominal pain, fever, and diarrhea. Left untreated, it can spread from the intestines to other organs. Diagnosis involves culture of stool or blood samples. Treatment involves antibiotics like ciprofloxacin or ceftriaxone for 1-2 weeks.

1. Pseudotuberculosis
-Ladi Anudeep
ISM-IUK

2. Introduction
• The genus Yersinia includes 18 species, three of which are important
human pathogens: Yersinia pestis, Yersinia enterocolitica, and Yersinia
pseudotuberculosis
• Y. enterocolitica and Y. pseudotuberculosis cause yersiniosis, a
diarrheal illness.
• The yersinioses are zoonotic infections of domestic and wild animals;
humans are considered incidental hosts that do not contribute to the
natural disease cycle.

3. Microbiology
• Y.tuberculosis is a gram negative, lactose-negative, oxidase-negative,
and urease-positive that causes illness similar to scarlet fever
• Humans occasionally get infected zoonotically most often food borne
route
• Structure consists of 2 antigens: Somatic-O antigen and flagellar-H
antigen
• Y. pseudotuberculosis has been isolated from a variety of mammals,
rodents and birds.
• Human is not a source of infection
• Yersinia pseudotuberculosis survives intracellularly

4. Transmission
• Transmission of yersiniosis is largely foodborne and occasionally
waterborne
• There are also reports of infection related to exposure to household pets
and transfusion of blood products
• Data on the transmission of Y. pseudotuberculosis are limited. Outbreaks
have been associated with consumption of contaminated lettuce, carrots,
and milk
• Risk factors associated with yersiniosis include consumption of
undercooked or raw pork products, exposure to untreated water, blood
transfusion, derangements of iron metabolism (such as cirrhosis,
hemochromatosis, aplastic anemia, thalassemia, and iron overload), and
other comorbid conditions (such as malignancy, diabetes, malnutrition, and
gastrointestinal illness).

5. Incidence of disease
• Sporadic yersiniosis has been observed worldwide. The incidence of
disease around the world increased substantially in the 1970s
• It was reported frequently in northern Europe, particularly in
Belgium, Norway, and the Netherlands; it is rarely observed in tropical
countries
• The incidence of Yersinia infections is highest in young children

6. Pathogenesis
• Organisms are ingested in contaminated foods, such as salads
containing carrots or lettuce, or as pork, or in water
• Incubation period: 8 days(avg)
• bacteria reach the terminal ileum and proximal colon, where they
penetrate through epithelial cells overlying gut-associated lymphoid
tissues including Peyer’s patches.
• As an intracellular infection, bacteria are taken up by macrophages,
where they survive and proliferate.
• Y. pseudotuberculosis acts to inhibit phagocytosis, allowing organisms
more access to mesenteric lymph nodes and the blood stream

7. • Results of this infection are mucosal ulcerations in the terminal ileum,
less commonly ulcerations in the ascending colon, necrotic lesions in
Peyer’s patches, and enlargement of mesenteric lymph nodes.
• Then gains access to blood stream and spreads to visceral organs i.e.,
liver and spleen

8. Clinical Features
• Includes intoxication syndrome, exanthemas infected GIT syndrome
• The most common clinical Y pseudotuberculosis syndromes are self-limited
enterocolitis and mesenteric lymphadenitis (pseudoappendicitis)
• The most common presentation is fever and abdominal pain or cramps
• About half the patients have back pain and a quarter of patients have
vomiting or diarrhea.
• The abdominal pain is often in the right lower quadrant corresponding to a
clinical picture of distal ileitis and regional lymphadenitis that gives rise to
the diagnostic appellation of “pseudoappendicitis.
• skin rash, strawberry tongue, hypotension, and lymphadenopathy are also
seen

9. • The infection can spread from the abdomen by way of the blood
stream, especially in immunocompromised persons, to cause
septicemia, liver or splenic abscesses, osteomyelitis, and septic
arthritis
• General intoxication symptoms like weakness, headache, arthralgias,
myalgias, anorexia, vomiting
• GIT syndrome: abdominal pain, diarrhea
• Y pseudotuberculosis is associated with postinfectious complications
such as erythema nodosum, reactive arthritis, iritis, and
glomerulonephritis.
• Erythema nodosum on the lower limbs is the exanthem found in
pseudotuberculosis

11. Diagnosis
• Y. pseudotuberculosis can be identified in cultures
• Stool culture is the preferred clinical specimen for patients with
intestinal symptoms
• Can also be detected by its features of being a Gram-negative bacillus
that is lactose-negative, oxidase-negative, and urease-positive
• General blood analysis shows leukocytosis, neutrophilia

12. Treatment
• Treatment is not warranted in most cases of self-limited mesenteric
lymphadenitis and ileitis
• Etiological treatment
• Antimicrobial treatment is preferred
• Resistance to penicillin, ampicillin, 1st gen cephalosporins is reported
• Susceptible to other beta-lactam agents, aminoglycosides,
tetracyclines, chloramphenicol, trimethoprim-sulfamethoxazole, and
fluoroquinolones

13. • Ciprofloxacin: 30mg/kg/day in 2 doses
• Ceftriaxone: 100mg/kg/day 1-2 times
• Cephazolin: mg/kg/day in 2 doses
• Streptomycin: 5mg/kg/day in 2 doses
• Trimethoprim(8mg/kg/day)-sulfamethoxazole(40mg/kg/day) in 2
doses