salmonella

1. What causes Pullorum Disease in poultry?

Salmonella pullorum.

2. What age group is most affected by Pullorum Disease?

Newly hatched chicks.

3. What are typical signs of Pullorum Disease in chicks?

White diarrhea, pasty vent, huddling, respiratory distress.

4. What ovarian lesion is seen in adult birds with Pullorum Disease?

Pedunculated and misshapen ovules.

5. What organism causes Fowl Typhoid?

Salmonella gallinarum.

6. What age group is affected by Fowl Typhoid?

Growers and adult birds.

7. What are key signs of Fowl Typhoid?

Greenish diarrhea, listlessness, paleness of comb/wattles, high mortality (~50%).

8. What lesion is characteristic of Fowl Typhoid?

Bile-stained dark red/brown liver with necrotic foci.

9. Is Salmonella motile?

Yes, except for S. pullorum and S. gallinarum.

10. Is Salmonella Gram-positive or Gram-negative?

Gram-negative.

11. What is the lactose fermentation status of Salmonella?

Lactose non-fermenter.

12. Does Salmonella produce H2S?

Yes.

13. Is Salmonella indole positive?

No.

14. Is Salmonella urease positive?

No.

15. Is Salmonella citrate positive?

Yes.

16. What are the TSI results for Salmonella?

K/A with H2S production.

17. How do Salmonella colonies appear on MacConkey agar?

Pale, non-lactose fermenting colonies.

18. What is the appearance of Salmonella on XLD or SS agar?

Black-centered colonies due to H2S.

19. What is the role of enrichment broth in Salmonella isolation?

Inhibits competing flora and enhances Salmonella growth.

20. Name two enrichment broths used for Salmonella isolation.

Selenite F broth, Rappaport-Vassiliadis broth.

21. When is enrichment broth used during isolation?

Before plating on selective agar, especially when organism is in low numbers.

22. What is the incubation time for enrichment broths?

Around 18–24 hours before subculture.

23. What are the three main antigens of Salmonella?

O (somatic), H (flagellar), Vi (capsular).

24. What is the function of the O antigen in Salmonella?

Heat-stable LPS; determines serogroup.

25. What is the function of the H antigen in Salmonella?

Heat-labile; flagellar antigen with phase variation (1° and 2°).

26. What is the role of the Vi antigen in Salmonella?

Capsule-like antigen that helps in immune evasion (e.g., in S. Typhi).

27. What toxins are produced by Salmonella?

Endotoxin (LPS) and enterotoxin.

28. What is antigenic phase variation in Salmonella?

Alternate expression of H1 and H2 flagellar antigens to evade immunity.

29. What classification scheme is used for Salmonella serotyping?

Kauffmann–White scheme based on O and H antigens.

30. How many O serogroups are currently defined in Salmonella?

46 O serogroups based on 67 O antigens (some skipped numbers).