Salmonella typhi

Question 1

Salmonella typhi Disease

Answer 1

Typhoid fever

Question 2

Characteristics of s.typhi

Answer 2

1_—Facultative gram-negative rods. 2_Nonlactose-fermenting

3_Produces H2S.

Question 3

Habitat of s.typhi

Answer 3

human colon only

Question 4

Transmission of s.typhi

Answer 4

fecal–oral route

Question 5

Pathogenesis of s.typhi

Answer 5

1_ Infects the cells of the reticuloendothelial system, especially in the ((liver and spleen))
2_ Endotoxin in cell wall causes fever.
3Capsule (Vi antigen) is a virulence factor.
4 No exotoxins known.
Decreased stomach acid resulting from ingestion of antacids or gastrectomy predisposes to Salmonella infections.
5_ Chronic carrier state established in gallbladder.
6_ Organism excreted in bile results in fecal–oral spread to others.

Question 6

Type of cells are infected by s.typhi

Answer 6

Infects the cells of the reticuloendothelial system, especially in the liver and spleen.

Question 7

Endotoxin in cell wall causes ______.

Answer 7

Fever

Question 8

Type of toxin in s.typhi

Answer 8

Endotoxin only

Question 9

Decreased stomach acid resulting from ingestion of _______ or _________ predisposes to Salmonella infections.

Answer 9

antacids or gastrectomy

Question 10

virulence factor of s.typhi

Answer 10

Capsule (Vi antigen)

Question 11

Chronic carrier state of s.typhi established in ______.

Answer 11

gallbladder

Question 12

Organism excreted in bile results in _______ spread to others.

Answer 12

fecal–oral

Question 13

Lab diagnosis of s.typhi

Answer 13

1_Gram stained smear and culture.
2_Non–lactose-fermenting colonies on EMB or MacConkey’s agar.
3TSI agar shows alkaline slant and acid butt, with no gas and a small amount of H2S.
4 Biochemical and serologic reactions used to identify species.
5_Identity can be determined by using known antisera against O, H, and Vi antigens in agglutination test.
Widal test detects agglutinating antibodies to O and H antigens in patient’s serum, but its use is limited.

Question 14

Colonies on EMB or MacConkey’s agar.

Answer 14

Non–lactose-fermenting colonies

Question 15

S.typhi on TSI agar

Answer 15

TSI agar shows alkaline slant and acid butt, with no gas and a small amount of H2S.

Question 16

How to identify species of salmonella?

Answer 16

Biochemical and serologic reactions used to identify specie.

Question 17

Name of the sero test for s.typhi

Answer 17

Widal test

Question 18

Define of Widal test ?

Answer 18

Identity can be determined by using known antisera against O, H, and Vi antigens in agglutination test.
Widal test detects agglutinating antibodies to O and H antigens in patient’s serum, but its use is limited.

Question 19

Most effective drug for s.typhi

Answer 19

Ceftriaxone

Question 20

What Type of drug used in patient who are not severly ill?

Answer 20

1_ Ampicillin

2_ trimethoprim-sulfamethoxazole

Question 21

Prevention from s.typhi

Answer 21

1_ Public health measures (e.g., sewage disposal, chlorination of the water supply, stool cultures for food handlers, and handwashing prior to food handling).

Two vaccines are in common use; one vaccine contains purified Vi polysaccharide capsule as the immunogen and the other contains live, attenuated S. typhi as the immunogen.

Question 22

Vaccines of s.typhi

Answer 22

Two vaccines are in common use :
1_ one vaccine contains(( purified Vi)) polysaccharide capsule as the immunogen and the other contains(( live)), attenuated S. typhi as the immunogen.