haemophilus, bordetella

Question 1

shape of haemophilus

Answer 1

small, bacilli or coccobacilli

Question 2

haemophilus motile?

Answer 2

no

Question 3

haemophilus gram + or -

Answer 3

-

Question 4

how is haemophilus categorized?

Answer 4

1) encapsulated - meningitis in young children

2) unencapsulated - ear aches, resp disease

Question 5

what is the function of the capsule in HIB and other encapsulated haemophilus strains?

Answer 5

• made of carbohydrates
• required for virulence and is antiphagocytic
• basis for serotyping

Question 6

what are the encapsulated haemophilus serotypes?

Answer 6

a, b, c, d, e, f

Question 7

what is the most important encapsulated haemophilus serotype and why?

Answer 7

b - has ribose instead of hexose in polysaccharide structure

Question 8

what is the most common clinical syndrome for haemophilus?

Answer 8

nasopharyngitis with accompanying otitis media. invasion of epithelium, bacteremia, involvement of meninges

Question 9

how does haemophilus enter the body?

Answer 9

resp tract, between children

Question 10

when are children most susceptible to haemophilus?

Answer 10

after passive immunity wears off, 6-12 months of age with risk up to 5 years

Question 11

vaccine for haemophilus?

Answer 11

yes - capsular against type b. linked to diphtheria toxoid for increased T cells and memory

Question 12

encapsulated haemophilus treatment

Answer 12

• third generation cephalosporin is used immediately because of increased resistance to ampicillin.
• augmentin - ampicillin+clavulanate - b-lactamase inhibitor to render ampicillin resistant strains sensitive to antibiotic. if b-lactamase negative, drop clavulanate

Question 13

location of non-capsule haemophilus

Answer 13

restricted to resp tract and ear

Question 14

clinical manifestations of non-capsuler haemophilus

Answer 14

• second most common cause of otitis after S pneumoniae
• conjunctivitis
• resp infections if underlying rest issues
• meningitis - usually a predisposing factor

Question 15

non-encapsulated haemophilus treatment

Answer 15

• amoxicillin with or without b-lactamase inhibitor

Question 16

diagnosis of haemophilus

Answer 16

• requires growth factors X and V
• preparation of chocolate agar releases both X and V from red blood cells
• encapsulated colonies are smooth
• suspected meningitis - blood and CSF taken

Question 17

other haemophilus pathogens

Answer 17

1) ducreyi - emerging STD - genital chancre
2) aegypticus - purulent conjunctivitis
3) parainfluezae - pharyngitis and endocarditis, part of natural flora

Question 18

major disease associated with bordetella

Answer 18

whooping cough

Question 19

bordetella gram + or -?

Answer 19

-

Question 20

shape of bordetella

Answer 20

small coccobacilli

Question 21

bordetella incubation period

Answer 21

7-10 days

Question 22

two stages or bordetella

Answer 22

1) catarrhal stage - runny nose, sneezing, low grade fever, mild cough
2) paroxysmal stage - bursts of coughing, high pitched whoop, cyanosis,

Question 23

how does bordetella infect?

Answer 23

• water droplets
• ciliated epithelia in trachea and nasopharynx
• adherence
• multiplication and toxin production

Question 24

four bordetella toxins

Answer 24

1) pertussis toxin - ribosylation of inhibitory G protein of adenylate cyclase, increased accumulation cAMP
2) adenylate cyclase toxin - cAMP from ATP, affects leukocytes
3) dermonecrotic toxin - vascular smooth muscle contraction, ischemic necrosis of lung tissue
4) tracheal cytotoxin - inhibits DNA synth, kills tracheal epithelial cells

Question 25

Main test for diagnosis of bordetella?

Answer 25

gram stain nasopharyngeal swab, direct anti-body test, culture on B-G

Question 26

drug of choice for bordetella?

Answer 26

erythromycin