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

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

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

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

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

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

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

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

Early 1900- Mary Mallon

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

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

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

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

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

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