Yersinia are gram-negative, facultative anaerobic, rod-shaped bacteria that include three main human pathogens: Y. pestis, Y. pseudotuberculosis, and Y. enterocolitica. Y. pestis causes bubonic, septicemic, or pneumonic plague via transmission from infected fleas or cough droplets. Symptoms include fever, chills, and swollen lymph nodes. Diagnosis involves culture and identification of the bacteria. Treatment includes antibiotics like ciprofloxacin. The other two species cause gastrointestinal illness transmitted via contaminated food or animal contact.

1. YERSINIA
Maira Jabeen
L1F18BSFT0021

2. Key characteristics
■ The genus is named for French bacteriologist Alexandre Yersin,
who in 1894 discovered Pasteurella pestis (now Yersinia pestis).
■ Group of ovoid- or rod-shaped bacteria.
■ Gram-negative bacteria.
■ Facultative anaerobes.
■ It is the causative agent of plague.
■ Several species of bacteria are motile below 37 °C (98.6 °F), all
Yersinia organisms are rendered non-motile at this temperature and
above.

3. Human Pathogens
■ In total, there are 11 species of Yersinia, three of
which are important human pathogens associated with
zoonotic infections.
1. Yersinia pestis
2. Yersinia pseudotuberculosis
3. Yersinia enterocolitica

4. Yersinia pestis

5. Yersinia
pestis
 Gram negative
 Non motile
 Rod shape bacterium
with no spores
 It infect humans via the
Oriental rat flea.
 It causes plague in
humans.

6. Bubonic Plague
■ Bubonic plague is an infection of the lymphatic system, usually
resulting from the bite of an infected flea.
■ It causes buboes.
 Under arms
 In neck
 In groin
 Incubation period is 1 week.

7. Signs and Symptoms
■ Sudden onset of fever and chills
■ Headache
■ Fatigue
■ Muscle aches

8. Septicemic plague
■ Septicemic plague occurs
when plague bacteria
multiply in your
bloodstream.
■ Majorly occurs if bubonic
plague is left untreated.
■ Fever and chills
■ Extreme weakness
■ Abdominal pain
■ Diarrhea and vomiting
■ Bleeding
■ Blackening and death of
tissue
Symptoms

9. Pneumonic plague
■ Pneumonic plague affects the lungs.
■ Least common but most dangerous.
■ Spread from person to person via cough droplets.
■ Progresses rapidly.
■ It may cause respiratory failure within two days of infection.

10. Symptoms
■ Cough with bloody mucus (sputum)
■ Difficulty in breathing
■ Nausea and vomiting
■ High fever
■ Headache
■ Weakness
■ Chest pain
Incubation period for this type of
plague is 2 to 3 days while it can
even cause death in 6 days if left
untreated.

11. Transmission
Flea drinks rat
blood that carries
bacteria.
Bacteria
multiply in fleas
gut.
Gut clogged
with bacteria.
Flea bites
human.
Human is
infected.

12. Diagnosis
■ Buboes:
The doctor use a needle to take a fluid sample from buboes.
■ Blood:
The doctor will take blood sample.
■ Lungs.
The doctor will take mucus through endoscopy.

13. Identification on culture media
■ Brain heart infusion broth
■ MacConkey agar
■ Sheep blood agar
Y. pestis appears as small rods by Gram staining by Giemsa or
Wayson staining.
Isolation ofY. pestis should
be performed at minimum
in a biosafety level 3
laboratory.

14. Results:
 The colonies formed on the agar plate after a 48-h incubation are
small.
 About 1 to 2 mm in diameter.
 They have raised centres and a flat periphery.

15. Treatment
Medication used for the treatment of plague are:
■ Ciprofloxacin
■ Levofloxacin
■ Moxifloxacin

16. Prevention
■ Rodent proof your home
■ Keep your pets free of fleas
■ Wear gloves
■ Use insect repellent

17. Yersinia enterocolitica
and
Y. pseudotuberculosis
■ Rod shape gram negative bacteria.
■ They multiply best at 25 degree centigrade.
■ They are present in intestinal tract of wild mammals, birds and
majorly in domestic animals.

18. Complications
■ It leads to inflammation
and ulceration and also the
appearance of leukocytes
in feces.
■ It may also leads to
mesenteric lymph nodes.
■ Abdominal pain
■ Vomiting
■ Diarrhea
■ Fever
Symptoms

19. Identification
■ They form lactose negative
colonies on MacConkey
Agar.
■ Biochemical tests are
positive at 25 degree
centigrade and negative at
37 degree centigrade.
■ Ciprofaloxin
■ Chloramphenicol
■ Trimethoprim-
sulfamethoxazole
Treatment
Prevention
 Sanitary precautions.
 Less contact with animals.
 Guard against contaminated
food.

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