Haemophilus

Question 1

General characteristic (2)

Answer 1

Gram Negative Coccobacilli (PLEOMORPHIC)

Capsulated

(Non-motile, non-spore forming)

Question 2

Growth (2)

Answer 2

Only on enriched media

Depends on blood for growth in lab (blood-loving)

Question 3

Growth Requirements (3)

Answer 3

X-factor —> Protoporphyrins essential for Catalases, Perioxidases, and Cytochromes of Electron Transport Chain

X-factor —> Supplied by Heat-stable iron-containing pigments e.g. “Blood-containing media”

V-factor —> Heat-labile, Coenzyme —> supplied by NAD or NADP

(NAD —> Present inside RBC)

Question 4

Media (4)

Answer 4

Chocolate agar (heated blood agar)

Blood with S.aureus (satellitism)

Nutrient media with X and V factors

5-10% CO2

Question 5

Habitat (1)

Answer 5

Normal flora of upper respiratory tract

Question 6

Haemophilus of medical importance (4)

Answer 6

H.influenzae

H.parainfluenzae

H.aegypticus

H.ducreyi

Question 7

Pathogenesis (3)

Answer 7

Capsule

Six types —> a, b, c, d, e, f

Invasive infections —> b

Question 8

What is the importance of the capsule? (4)

Answer 8

Virulence (anti-phagocytic) resist killing by immune cells —> severe disease

Antigenic —> immune cells produce protective antibodies

Direct antigen detection from clinical samples by LATEX AGGLUTINATION using anti-capsular antibodies

Vaccine by using capsule as target

Question 9

Normal carriage (2)

Answer 9

STRICT HUMAN PATHOGEN

Nasopharynx of healthy

Question 10

Invasive infections most common in who?

Answer 10

CHILDREN <2 years

Question 11

Invasive Infections (6)

Answer 11

1- Meningitis (60%)

2- Epiglottitis (15%)

3- Bacteraemia (10%)

4- Cellulitis (5%)

5- Pneumonia (5%)

6- aseptic arthritis (5%)

Question 12

Meningitis (4)

Answer 12

MOST COMMON INVASIVE disease

DROPLET infection

Mortality = 5%

NEUROLOGICAL COMPLICATIONS especially HEARING LOSS

Question 13

Non-invasive Disease (3)

Answer 13

Otitis media

Sinusitis

Exacerbation of COPD

Question 14

Treatment (3)

Answer 14

Ampicillin —> 25% resistance of type b

Cefotaxime + Ceftriaxone —> Meningitis and other invasive

Amoxicillin-clavulinic acid + Azithromycin —> Respiratory infections

Question 15

Immunization

Answer 15

Hib vaccine (conjugate vaccine)

Infants 2, 3, 4 months old

Question 16

Chemoprophylaxis (2)

Answer 16

Rifampicin

Ciprofloxacin

Question 17

H.aegypticus

Answer 17

Epidemic conjunctivitis

Question 18

H.ducreyi

Answer 18

STI

PAINFUL penile ulcer ‘’Chancroid”

Treatment = Tetracycline