54. Genera Shigella and Yersinia.

Question 1

Shigella Habitat Morphology culture Biochemistry and Pathogenecity?

Answer 1

SHIGELLA

1. Habitat: • intestine (primates), sewage
2. Morphology: • no flagella
3. Culture: • DC (deoxycholate citrate) agar
4. Biochemistry: • resembles E. coli, but lactose negative or late fermentation
5. Pathogenicity:

• S. dysenteriae,

S. flexneri,

S. sonnei,

S. boydii: human bacillary dysentery

Question 2

Shigella Biochemical characteristics?

Answer 2

Question 3

Yersinia species?

Answer 3

YERSINIA Species

• Y. pestis
• Y. pseudotuberculosis
• Y. enterocolitica
• Y. ruckeri

Question 4

Y.pseudotuberculosis Habitat Morphology and Staining?

Answer 4

Y. pseudotuberculosis

1. Habitat: • intestine, water
2. Morphology: • 1-2 µm coccoid rods, • flagella 22oC
3. Staining: • Gram - negative • bipolar staining

Question 5

Y.pseudotuberculosis Culture and Biochemistry?

Answer 5

4. Culture: • not fastidious • optimal temperature 30 oC, • replication: 4-42 oC, • small colonies • selective culture: • on low selective capacity media for Enterobacteriaceae
5. Biochemistry: • lactose -

Question 6

Y.pseudotuberculosis Biochemical characteristics?

Answer 6

Question 7

Y.pseudotuberculosis antigens and pathogenecity?

Answer 7

6. Antigens:
   • O antigen: 8 serogroups,
   • 5 H antigens
   • composite antigens
7. Pathogenicity:
   • rodents (rodentiosis),
   • turkey, pheasant, quail (septicaemia, abscesses),
   • cattle, swine, sheep (abortion),
   • human

Question 8

Y.enterocolitica habita morphology and culture?

Answer 8

Y. enterocolitica

1. Habitat: • intestine, water
2. Morphology, staining • middle sized rods • Gram-negative
3. Culture: • optimal temperature: 22 oC • selective culture: • Na-oxalate + bile salts

Question 9

Y.enterocolitica antigens and pathogenecity?

Answer 9

4. Antigens: • O antigens: • 34 O-groups, • O9: cross-reaction with Brucella-species • H antigens • 20 H antigens
5. Pathogenicity: • human: • gastro-intestinal infection, abscesses • swine, rabbit: • intestine, mesentherial ly

Question 10

Y.ruckeri Biochemistry and Pathogenecity?

Answer 10

Y. ruckeri

1. Biochemistry: • inactive
2. Pathogenicity: • trout septicaemia, kidney (red mouth disease)