1. Typhoid/ Enteric fever
Dr. Jyotsna Agarwal
Professor, Dept. Microbiology
KGMU

2. Salmonella Salmonella is Gram-negative, rod-shaped
Facultative anaerobe in family Enterobacteriaceae
Motile, Non lactose fermenting
Over 2400 serotypes

3. Faeco-oral transmission
Refrigeration does not kill bacteria, Heat at 600C destroys

6. Pathogenesis Bacteria penetrates intestinal cell in ileocaecal region
Inflammatory response to bacterial multiplication in the cell
Prostaglandins secreted
Increase in C-AMP

8. Virtually non existent in developed world
In developing countries endemic
Typhoid more common than paratyphoid

9. Pathogenesis of Enteric fever
M cells on Peyers patches
Invade intestinal lining cells
bloodstream (primary bacteremia)
Phagocytosis
Transported (R E system), continue to replicate

10. Pathogenesis contd…
Second week: re-enter bloodstream (secondary bacteremia) endotoxemia
Second to third week: gallbladder, secreted in bile, re-infect intestinal tract

11. Complications: Intestinal haemorrhage, perforation, cholecystitis
Less commonly: Bronchopneumonia, arthritis, osteomyelitis

13. Early Mary Mallon

15. Diagnosis of Typhoid Fever
Clinical:
For Lab diagnosis, specimen & diagnostic tests according to duration of fever:
Blood for Culture
WIDAL
Stool culture
Urine culture

16. Blood Culture In blood culture bottle
Repeated cultures may be required
Subculture on MacConkey medium (NLF colony)
Clot culture- put clot in blood culture bottle, lyse it with streptokinase in B/C bottle
Use serum for WIDAL

17. Selective media for subculture from blood culture bottle: MacConkey, Wilson Blair, Tellurite blood agar
Enrichment broth for culture of stool/urine: Selenite F broth, Tetrathionate broth

18. Serological test- WIDAL
For detecting antibody
Agglutination test
Endemic titre
Paired sera
For carriers - antibody against Vi antigen
Rapid test- Typhi dot

20. Salmonella vaccines
TAB: Salmonella typhi, paratyphi A &B, killed whole cell
Oral Ty21-A: Live attenuated, Salmonella typhi vaccine
Vi capsular polysaccharide vaccine

21. Summary- Enteric fever
S. typhi / S. paratyphi
Mode of spread /Pathogenesis
Clinical features / Complications
Laboratory diagnosis
Treatment/vaccines