Salmonella

Question 1

What is the pathogenesis of typhoid fever?

Answer 1

1. Infection starts in the small intestine → Minimal early GI symptoms
2. Bacteria multiply in Peyer’s patches → Spread to liver, gallbladder, spleen
3. Bacteremia develops → Possible chronic carrier state

Question 2

What factors increase the risk for Salmonella septicemia?

Answer 2

1. Medical conditions – Chronic disease, cancer, sickle cell anemia
2. Immune status – Immunocompromised individuals, previous tissue damage
3. Foreign materials – Presence of vascular grafts

Question 3

What are the major complications of Salmonella infection?

Answer 3

1. Intestinal – Hemorrhage, perforation
2. Systemic – Septicemia, bacteremia, metastatic abscesses
3. Bone & vascular – Osteomyelitis (sickle cell patients), vascular graft infections

Question 4

What are the key laboratory features of Salmonella?

Answer 4

1. Colony characteristics – Colorless colonies, non-lactose fermenting, H₂S production (black butt in TSI)
2. Biochemical features – Alkaline slant & acid butt, S. typhi has less H₂S production
3. Special media – Grows on MacConkey’s agar, EMB agar, and TSI agar

Question 5

What are the key preventive measures against Salmonella infection?

Answer 5

1. Hygiene & sanitation – Proper sewage treatment, handwashing, chlorinated water
2. Food safety – Pasteurization of milk, proper cooking of poultry, eggs, and meat
3. Vaccination – IM Vi capsular polysaccharide, oral live attenuated (Ty21a), conjugate vaccine