Haemophilus influenzae

Question 1

Diseases of Haemophilus influenzae

Answer 1

1_Sinusitis, otitis media, and pneumonia ( are common).
 2_Epiglottitis is (uncommon) but  H. influenzae  is the most important  cause. 
3_ Haemophilus  influenzae  used to be a leading cause of ((meningitis)), but the vaccine has greatly reduced the number of cases.

Question 2

Characteristics of Haemophilus influenzae

Answer 2

1_Small gram-negative (coccobacillary) rods. 2Requires factors X (hemin) and V (NAD) for growth.
3 six capsular polysaccharide types,
4type b causes 95% of invasive disease.
5(( Type b capsule is polyribitol phosphate)).

Question 3

Habitat of Haemophilus influenzae

Answer 3

Habitat is the upper respiratory tract. .

Question 4

Transmission of Haemophilus influenzae

Answer 4

Transmission is via respiratory droplets

Question 5

Pathogenesis of Haemophilus influenzae

Answer 5

1_Polysaccharide capsule is the most important determinant of virulence.
2Unencapsulated (“untypeable”) strains cause mucosal infections but not invasive infections.
3 IgA protease is produced.
4_Most cases of meningitis occur in children younger than 2 years of age, because maternal antibody has waned and the immune response of the child to capsular polysaccharides can be inadequate. No exotoxins identified.

Question 6

Why most cases of meningitis occur in children younger than 2 years of age?

Answer 6

because maternal antibody has( waned ) and the immune response of the child to capsular polysaccharides can be inadequate.

Question 7

What require Haemophilus influenzae to growth ?

Answer 7

Requires factors X (hemin) and V (NAD) for growth

Question 8

Which of sixith Polysaccharide capsule cause invasive disease ?

Answer 8

type b causes 95% of invasive disease. Type b capsule is polyribitol phosphate.

Question 9

Laboratory Diagnosis of Haemophilus influenzae

Answer 9

1Gram-stained smear plus culture on chocolate agar.
2Growth requires both factors X and V.
3_Determine serotype by using antiserum in various tests (e.g., latex agglutination).
4 Capsular antigen can be detected in serum or cerebrospinal fluid.
5 Serologic test for antibodies in patient’s serum not useful.

Question 10

culture of Haemophilus influenzae on ______ agar.

Answer 10

chocolate agar

Question 11

What using to determine serotype of Haemophilus influenzae

Answer 11

by using antiserum in various tests (e.g., latex agglutination).

Question 12

Capsular antigen can be detected in ____ or _____.

Answer 12

serum or cerebrospinal fluid

Question 13

Treatment of

Answer 13

1_Ceftriaxone is the treatment of choice for meningitis.

2_Approximately 25% of strains produce β-lactamase.

Question 14

Prevention (vaccine) for Haemophilus influenzae

Answer 14

1_Vaccine containing the type b capsular polysaccharide conjugated to diphtheria toxoid or other protein is given between 2 and 18 months of age. Rifampin can prevent meningitis in close contacts.