Salmonella

Question 1

Common characteristics of Salmonella, Shigella, Yersinia (9)

Answer 1

Enterobacteriacae 
Aerobe and Facultative anaerobes 
Gram Negative Bacilli
Motile or Non-motile 
FERMENT GLUCOSE 
OXIDASE NEGATIVE 
Reduce nitrate to nitrite 
Produce LACTOSE NOM-FERMENTING colonies on Mackonkey agar
Cause disease within hand outside intestinal tract

Question 2

General Characteristics (2)

Answer 2

MOTILE

BLACK-centered pale colony on TELLURITE-containing media (Salmonella-shigella agar) due to production of H2S

Question 3

Classification

Answer 3

1- Typhoid (HUMAN INTESTINE)—>Salmomella typhi, Salmonella paratyphi A, B, C

2- Non-typhoid (ANIMAL INTESTINE)

Question 4

Enteric (Typhoid) Fever (4)

Answer 4

Caused by S.typhi and S.paratyphi

Source of organisms is HUMAN ONLY

Transmitted by FECAL-ORAL route (contaminated food and water)

Disease: Constipation, Diarrhea, HEPATO-SPLENOMEGALY, MACULOPAPULAR RASH (rose spots), CHRONIC CARRIER STATE due to DISEASED GALL BLADDER

Question 5

Virulence of Enteric Fever Organisms (3)

Answer 5

1- INTRACELLULAR pathogen —> Multiply within MACROPHAGES
2- CAPSULAR antigen —> S.typhi and S.paratyphi C
3- LPS —> Production of PROINFLAMMATORY CYTOKINES (TNF, IL-1, IL-6) mediating FEVER

Question 6

Non-typhoid Salmonella

Answer 6

(S.typhimurium, S.enteritidis)

Diseases: GASTROENTERITIS of inflammatory nature (major cause of FOOD POISONING), MENINGITIS, OSTEOMYELITIS (CHILDREN with SICKLE CELL ANEMIA prone), METASTATIC ABSCESS (at site of anuerysm and infarct)

Question 7

Non-typhoid Salmonella- Reservoirs (5)

Answer 7

Poultry (intestine), Eggs (infection of oviducts), Cattle, Pets (dogs, snakes, turtles), Lizards

Question 8

Non-typhoid Salmonella- Virulence Factors (3)

Answer 8

1- Multiply within MACROPHAGES
2- INVADE INTESTINAL MUCOSA (terminal ileum and colon)
3- Produce ENTEROTOXINS (mediating Diarrhea)

Question 9

S.typhi Vaccine (2)

Answer 9

Live oral vaccine and Vi antigen-based injectable vaccine