Plague is caused by the bacteria Yersinia pestis, a zoonotic bacteria usually found in small mammals and their fleas. People infected with Y. pestis often develop symptoms after an incubation period of one to seven days. There are two main clinical forms of plague infection: bubonic and pneumonic. Bubonic plague is the most common form and is characterized by painful swollen lymph nodes or 'buboes'. Plague is transmitted between animals and humans by the bite of infected fleas, direct contact with infected tissues, and inhalation of infected respiratory droplets. Plague can be a very severe disease in people, with a case-fatality ratio of 30% to 60% for the bubonic type, and is always fatal for the pneumonic kind when left untreated. Antibiotic treatment is effective against plague bacteria, so early diagnosis and early treatment can save lives. Currently, the three most endemic countries are the Democratic Republic of the Congo, Madagascar, and Peru. Y. pestis survives and produces F1 and V antigens within blood cells such as monocytes, but not in neutrophils. Natural or induced Immunity is achieved by the production of specific antibodies against F1 and V antigens Antibodies against F1 and V induce phagocytosis by neutrophils Y.pestis causes plague ( a zoonotic diseases which is transmitted fron rats and rodents to humans by infected fleas) Fleas-blood sucking wingless insect of the order Siphonaptera Occasionally the infection occurs by inhaling the organism in the airborne droplets or By handling the infected rodents or domestic animals (e.g cats and dogs) that harbour infected fleas Bubonic plague Flea (bite) to humans Pneumonic plague Human to human after inhalation and>lungs though blood stream Septicaemic plague Plague-Zoonotic disease Spread from domestic rats to man by bite of rat flea Plague-greatest killer in history of mankind Severe epidemics In India-out break in 1994 (Maharashtra, Gujarat, UP, MP, Karnataka) In 2002-outbreak in Shimla Scattered natural foci still exist:kolar,Bead-Lathur belt in Maharashtra, Shimla and Uttaranchal Self limiting gastroenteritis in young children Mesenteric adenitis and inflammatory terminal ileitis in older children Systemic disease seem in aduld:bacteremia,meningitis arthlgia,erythema nodosum Pathogen of rodents, particularly guinea pigs Septicemia with mesenteric lymphadenitis similar to appendicitis Motile at 22 degree centigrade Pasteurella species are spherical, ovoid or rod-shaped cells 0.3-1.0µm in diameter and 1.0-2.0µm in length Cells are Gram negative, and occur singly, or in pairs or short chains Bipolar staining may be seen Capsules may be present All species are non-motile Facultative anaerobic Microscopy Gram-negative coccobacilli measuring 1 to 2 μm in length. Many pathogenic isolates are encapsulated Cultural characteristics Primary isolation media Blood agar incubated in 5-10% CO2 at 35-37°C for 16–48hr ,Colonies are grey and viscous but rough irregular colonies occur

1. Genus Yersinia and Pasteurella
Department of Microbiology and
Immunology
Presenter; Japhet Peter
Supervisor Dr. Salim Masoud

2. Presentation outline
• Introduction
• Morphology and identification
• Epidemiology
• Pathology/ pathogenesis
• Clinical disease
• Laboratory Diagnosis
• Treatment , Prevention and control

3. Genus Yersinia
• The Yersinia is a facultative gram negative bacilli
transmitted by rodents( so this zoonotic diseases
transmitted to man accidentally)

4. YERSINIA
• Short, gram-negative rods showing bipolar
staining ,facultative anaerobes
Three medically important species:
1. Y.pestis-Plague
2. Y.pseudotuberculosis-rodents
3. Y.enterocolitica-enteric disease in human
 Primary pathogens of rodents and accidentally
infect man

5. Morphology
• Non motile
except(pseudotuberculosis&Y.enterocolitic
a)
• Named after Alexander Yersin-discovered
plague bacilli

6. YERSINIA SPECIES
 Yersinia pestis – Causes Plague
 Yersinia enterocolytica- Causes
Gastroenteritis
 Yersinia pseudotuberculosis- Causes
necrotic lesions in the
liver, spleen & lymph nodes

7. YERSINIA PESTIS
 Causative agent of plague
MORPH:OLOGY
Small, gram negative bacilli-bipolar staining
SAFETY PIN APPEARANCE

8. CULTURE
• Nutrient agar: small transparent colonies
• Blood agar: non hemolytic, dark brown colonies
due to absorption of haemin pigment
• Mac Conkey agar: on lactose fermenting
colonies
• Ghee broth: organisms grown in s flask of oil or
ghee a characteristic growth occurs which hangs
down from the under the surface of the oil,
resembling stalacite(stalacite growth)

9. Biochemical reaction
• Ferment glucose, Mannitol and maltose
with production of acid only
• Catalase positive
• Indole, urease, citrate, MR- both are
negative

11. PATHOGENESI and /PATHOLOGY
 Pathogenicity of Y. pestis is in part due to two
anti-phagocytic antigens>named
-F1 (Fraction 1) important for
- and V vilurence
 These antigens are produced by the bacterium
at 37°C.
 Virulence factors are required for bacterial
adhesion and injection of proteins into the host
cell.

12. PATHOGENESIS cont
 Y. pestis survives and produces F1 and V
antigens within blood cells such as monocytes,
but not in neutrophils.
 Natural or induced Immunity is achieved by the
production of specific antibodies against F1
and V antigens
 Antibodies against F1 and V induce
phagocytosis by neutrophils

13. PATHOGENESIS cont--
 Y.pestis causes plague ( a zoonotic
diseases which is transmitted fron rats
and rodents to humans by infected fleas)
Fleas-blood sucking wingless insect of
the order Siphonaptera

14. PATHOGENESIS cont……..
 Occasionally the infection occurs by
inhaling the organism in the airborne
droplets or
 By handling the infected rodents or
domestic animals (e.g cats and dogs) that
harbour infected fleas

15. Different forms of the disease
(PLAGUE)
 Bubonic plague
– Flea (bite) to humans
 Pneumonic plague
– Human to human after inhalation
and>lungs though blood stream
 Septicaemic plague

16. Epidemiology
• Plague-Zoonotic disease
• Spread from domestic rats to man by bite of rat flea
• Plague-greatest killer in history of mankind
• Severe epidemics
• In India-out break in 1994 (Maharashtra, Gujarat,
UP, MP, Karnataka)
• In 2002-outbreak in Shimla
• Scattered natural foci still exist:kolar,Bead-Lathur
belt in Maharashtra, Shimla and Uttaranchal

17. BUBONIC -SYMPTOMS
 Sudden headache, malaise, myalgia
 High fever
 Lymph nodes to become hot & swollen
( Occasionally lymph nodes in the neck and
armpits are involved
 hemorrhagic swelling ( buboes)

18. PNEUMONIC SYMPTOMS
 Acquired person to person through inhalation
 Flu-like symptoms
 Rapid progression to hemoptysis
 Rapid death (1-3 days

19. Septicaemic plague
• Presence of bacteria in the blood
• Usually complication of bubonic or
pneumonic plague
• Massive hemorrhage- BLACK DEATH

21. DIAGNOSIS
 Examination of Buboes aspirate, blood, sputum
or spinal fluid for culture and smear
 Smear- is examined after staining with the
Giemsa stain or wayson’s ( bipolar
appearance)

22. BIOCHEMICAL TEST
• Urease - ,oxidase –
• Non-motile at room temperature
Y. enterocolytica
• Urease + oxidase -
• Motile at room temperature ( non motile at 35-37

23. TREATMENT AND PREVENTION
 Streptomycin, tetracycline, ciprofloxacin or
doxycycline (chloramphenicol for meningitis)-
no drug identified as resistant to Y.pestis
 Hospitalization and strict isolation, extreme
precaution (mask, gloves, etc.)
 Minimize domestic rat population

24. YERSINIA ENTEROCOLITICA
• Causative of gastroenteritis
-Transmission-fecal contamination, domestic an
animals (water, milk and meat)
Epidemiology-World wide
NOTE :can survive in refrigerator temperatures(
can use” cold enrichment’’ to isolate)

25. Human diseases
• Self limiting gastroenteritis in young
children
• Mesenteric adenitis and inflammatory
terminal ileitis in older children
• Systemic disease seem in
aduld:bacteremia,meningitis
arthlgia,erythema nodosum

26. Yersinia pseudotuberculosis
• Pathogen of rodents, particularly guinea
pigs
• Septicemia with mesenteric lymphadenitis
similar to appendicitis
• Motile at 22 degree centigrade

29. GENUS PASTEURELLA

30. DEFINITION
• Pasteurella is a genus of Gram
negative, facultatively anaerobic bacteria
Pasteurella species are non
motile and pleomorphic, and often exhibit bipolar
staining ("safety pin" appearance)
30

31. MORPHOLOGICAL CHARACTERISTICS
• Pasteurella species are spherical, ovoid or rod-
shaped cells 0.3-1.0µm in diameter and 1.0-
2.0µm in length
• Cells are Gram negative, and occur singly, or in
pairs or short chains
• Bipolar staining may be seen
• Capsules may be present
• All species are non-motile
• Facultative anaerobic
31

32. MORPHOLOGY AND IDENTIFICATION
Microscopy
• Gram-negative coccobacilli measuring 1 to 2 μm
in length.
• Many pathogenic isolates are encapsulated
Cultural characteristics
• Primary isolation media
– Blood agar incubated in 5-10% CO2 at 35-37°C for
16–48hr ,Colonies are grey and viscous but rough
irregular colonies occur frequently
• Organisms grow in culture on a variety of
commercial media, including chocolate agar
media.
32

33. 33

34. • Pasteurella multocida growing on sheep blood agar
(SBA) and chocolate (CHOC) agar.All Pasteurella spp.
grow on SBA and CHOC agar, producing grayish
colonies.The MacConkey (MAC) agar plate is negative
for growth
34

35. BIOCHEMICAL REACTIONS
• The majority of strains are fermentative and test
indole, catalase, oxidase, and sucrose positive.
• Sensitivity to penicillin
– Pasteurella species are typically penicillin
susceptible and so a zone of inhibition around
a 10-U penicillin disc may aid differentiation
from other Gram negative bacilli
• Nitrates are reduced to nitrites by almost all
species.
35

36. ANTIGENIC STRUCTURE
• There are 5 capsular antigens (named as
A,B,D,E and F) and 11 somatic antigens (named
as 1,2,3,4,5,6,7,8,9,10,11)
• Recombinations of capsular and somatic
antigens produces a given Pasteurella serotype
e.g. A:1,A:4,B:1,B:2,D:1,D:2
• Several serotypes are involved in human
infection (notably A and D) serotypes and
normally these are contracted from animal bites
36

37. VIRULENCE FACTORS
Fimbriae
• Adherence to mucosal epithelial cells in the upper
respiratory tract, particularly in the tonsils.Eg P.
multocida strains.
Polysaccharide capsules.
• Most virulent Pasteurella strains (P. multocida) produce
polysaccharide capsules which confers
– Resistance to desiccation,
– promotion of adherence,
– Resistance to phagocytosis and complement-
mediated killing.
37

38. Transferrin
• Binding of which by some pathogenic
Pasteurella strains ensure an iron supply
necessary for growth.
38

39. TOXIN
• Leukotoxin
– Produced by Pasteurella haemolytic
– toxic to ruminant leukocytes that it impair
cellular response in lung tissue stimulate
inflammatory response.
• The ToxA protein
– Produced by P. multocida, is a cause of
progressive atrophic rhinitis in pigs.
39

40. HUMAN INFECTIONS CAUSED
BY PASTEURELLA
Bacteria Diseases
Pasteurella multocida Cellulitis and adenitis at the site of
cat- or dog-bite wound, exacerbation of
respiratory tract infections, and
systemic
infection in immunocompromised
patients
Pasteurella canis Dog-bite wound infection
Pasteurella dagmatis Dog-bite wound infection
40

41. • Human infections –rare

42. THE END