bacterial organisms

1. Yersinia
pseudotuberculosis
M.S.SWETHA(BP231508)
M.SC. MICROBIOLOGY
SACRED HEART COLLEGE

2. GENERAL CHARACTERISTICS:
Gram’s classification: Gram negative
Bacteria
Shape: Pleomorphic rod
(cocco bacillus)
Arrangement: Sandwich structure
consists of 9 strands
Motility: Motile at 22c-25c,But not
motile in 37c

3. Size:0.5µm to 0.8µm in
diameter
Family:Enterobacteriaceae.
Capsule: Absent
Endospore: Absent

4. Respiration:
Aerobic/facultative anaerobic
Optimum temperature : 28-29c
Optimum pH: 5.0 to 9.6
Habitat : Soil or Water,
Gastero intestinal tract of
human and animals

5. DISEASE TRANSMISSION:
1
• Contaminated by animal faeces
(fecal oral route)
2
• While ingest meats, Especially pork
3
• Ingest unpasteurized milk or contaminated
water

6. VIRULENCE FACTORS:
1. Type III Secretion System (T3SS)
2. Yersinia Outer Proteins (Yops)
3. Invasins
4. Adhesins
5. Lipopolysaccharide (LPS)
6. Biofilm Formation
7. Iron Acquisition Systems
8. Temperature Sensing and Regulation

7. PATHOGENESIS
 The presence of Plasmids (pYV) enables virulent Yersinia to
survive and multiply in lymphoid tissues of their host.
 The pYV codes for an outer membrane protein YadA (Yersinia
adhesin A), and a set of highly regulated secreted proteins, called
Yops (Yersinia outer proteins). Protein YadA is a major
outermembrane protein, which forms a fibrillar matrix on the
surfaces of Y. pseudotuberculosis, and is only expressed at 37°C.
 Yops protect Yersinia from the macrophage by destroying its
phagocytic and signaling capacities, and finally, inducing
apoptosis. Invasion of epithelial layers require at least two
chromosomal genes, inv (invasion)and ail (attachment invasion
locus).

8.  The inv codes for Inv, an outer membrane protein, which appears to play a
vital role in promoting entry into epithelial cells of the ileum during the initial
stages of Y. pseudotuberculosis infections.
 Y. pseudotuberculosis migrate after ingestion through the stomach and the
small intestine to the terminal end of ileum.The bacteria bind to the follicle-
associated epithelium of the Peyer’s patches.
 Y. pseudotuberculosis penetrate the intestinal mucosa, through M cells,
specialized cells involved in intestinal antigen uptake.Attachment and
invasion of M cells are mediated by chromosomal determinants, Inv and Ail
proteins, and plasmid determinant YadA.
 Usually the infection is limited to the intestinal area, but sometimes the
microorganisms drain into the mesenteric lymph nodes and give rise to a
systemic infection.

9. INCUBATION PERIOD :
4 to 10 days
INFECTIVE DOSE :
relatively low

10. Clinical manefestation
1. Gastrointestinal Symptoms:
 Abdominal pain
 Diarrhea, which may be watery or bloody
 Nausea and vomiting
2. Fever:
 Yersinia pseudotuberculosis infections can be accompanied by a
fever.
3. Mesenteric Lymphadenitis:
 Yersinia pseudotuberculosis commonly causes mesenteric
lymphadenitis, which is the inflammation of lymph nodes in the
abdomen.
 This can lead to abdominal tenderness and swelling.

11. 4.Pseudoappendicitis:
 Yersiniosis can mimic appendicitis, causing symptoms such as right
lower abdominal pain, fever, and an elevated white blood cell
count.
 It's important to differentiate Yersinia pseudotuberculosis
infection from true appendicitis.
5.Arthritis and Reactive Arthritis:
 In some cases, Yersinia pseudotuberculosis infections may lead to
joint symptoms, including arthritis.
 Reactive arthritis, characterized by joint inflammation following
an infection, can also occur.
6.Skin Manifestations:
 Skin rash or erythema nodosum (painful subcutaneous nodules)
may occur in some individuals with Yersinia pseudotuberculosis
infection.

12. Laboratory diagnosis
MICROSCOPIC EXAMINATION
 gram staining- Pink coloured gramNegative cocci
 Motility test- Non motile

13. COLONY MORPHOLOGY ON CULTURE MEDIUM
 Yersinia Selective Agar
Growth with dark pink center & bile precipitate. No
transparent zone around the colonies.
 CIN (Cefsulodin -Irgasan-Novobiocin) agar
smaller, deep red with a sharp border surrounded by a
translucent zone.

14. Biochemical test
 oxidase-negative
 catalase-positive
 indole-negative
 urease-negative
 Citrate Utilization Test - negative
 Triple Sugar Iron Agar (TSI) test- an alkaline slant and an acid butt
with no gas or hydrogen sulfide production on TSI agar.
 lysine decarboxylase test- positive
 Gelatin Hydrolysis test - positive

15. Treatment
1. Ciprofloxacin: This fluoroquinolone antibiotic is often
effective against Yersinia pseudotuberculosis.
2. Levofloxacin: Another fluoroquinolone that may be
prescribed for Yersinia pseudotuberculosis infections.
3. Trimethoprim/Sulfamethoxazole (TMP/SMX): This
combination antibiotic is sometimes used for Yersinia
infections.
4. Doxycycline: This tetracycline antibiotic may be considered,
especially in cases where fluoroquinolones are not suitable.
5. Ampicillin: This beta-lactam antibiotic may be effective
against Yersinia pseudotuberculosis. However, the bacterium
is often resistant to ampicillin.

16. THANK YOU…