Haemophilus

Question 1

Morphology/staining of Haemophilus species:

Answer 1

Small, short (0.5-1.5 microns) Gram-negative coccobacilli

Can appear pleiomorphic

Non-motile and non-spore forming

Question 2

Haemophilus oxidase:

Answer 2

Oxidase positive

Question 3

Haemophilus catalase:

Answer 3

Catalase Positive

Question 4

Haemophilus media:

Answer 4

Grows best on chocolate agar supplemented with key growth factors:

“X” (hemin or hematin)
“V” (nicotinamide adenine dinucleotide)

Some serotypes require CO2 for enhanced growth

Question 5

Name the diseases caused by:
H. parainfluenzae
H. aphrophilus 
H. ducreyi
H. aegyptius

Answer 5

H. parainfluenzae – bacteremia, endocarditis

H. aphrophilus - endocarditis

H. ducreyi – Chancroid (STD)

H. aegyptius - conjunctivitis

Question 6

H. influenzae Transmission:

Answer 6

via respiratory droplets

Question 7

H. influenzae Mechanism of infection (4 steps)

Answer 7

1. Colonization of throat and nasopharynx
2. Adherence to mucosal epithelium with pili, adhesins, and other outer membrane proteins
3. The bacteria get endocytosed and tissue invasion occurs
4. For Type B, polysaccharide capsule is major virulence factor and promotes immune evasion, bloodstream invasion, and more severe, disseminated infection

Question 8

Predominate demographic of H. influenzae Type B infection:

Answer 8

Infants and young children with peak incidence around 6 months – 2 years

Question 9

H. influenzae invasive disease is caused by:

Answer 9

H. influenzae Type B, rarely non-encapsulated strains

Question 10

H. influenzae non-invasive disease is caused by:

Answer 10

Non-encapsulated strains (H. influenzae Type A, D, and E)

Question 11

Which type of H. influenzae Clinical Disease has a vaccine?

Answer 11

Invasive disease caused by H. influenzae Type B.

Question 12

Which type of H. influenzae Clinical Disease does not have a vaccine?

Answer 12

Non-invasive disease caused by non-encapsulated strains

Question 13

Predominate demographic of H. influenzae non-invasive infection:

Answer 13

Affects older children and adults

Question 14

Clinical manifestations of H. influenzae invasive disease:

Answer 14

Meningitis

Epiglottitis – sudden onset fever, sore throat, cough, stridor, red/swollen

Septic arthritis, pneumonia, bacteremia, cellulitis (usually face/cheek)

Osteomyelitis

Question 15

4 Clinical manifestations of H. influenzae non-invasive disease:

Answer 15

Otitis media

Sinusitis

Pneumonia: Acute exacerbations of chronic obstructive lung disease (COPD)

Conjunctivitis

Question 16

H. influenzae diagnosis:

Answer 16

Gram stain

Culture of clinical specimens on enriched agar

Collect specimen from CSF, joint fluid, blood, or lower respiratory tract

Nucleic acid amplification (not widely used yet)

Question 17

H. influenzae treatment:

Answer 17

Severe invasive disease: 2nd and 3rd generation cephalosporins

Less severe and non-invasive disease: amoxicillin/clavulanate, macrolides, fluoroquinolones, and trimethoprim/sulfamethoxazole

Question 18

Describe the composition of the HiB vaccine:

Answer 18

Conjugate vaccine of polysaccharide capsule antigens and other protein, including diphtheria toxoid, N. meningitidis OMP, tetanus toxoid

Question 19

What is used as Prophylaxis for hHiB contacts:

Answer 19

rifampin

Question 20

Describe vaccination series for HiB:

Answer 20

Universal vaccination all children

Two or three dose primary series: 2, 4, (6) months

Booster dose between 12-15 months