Haemophilus and Bordetella

Question 1

What are the general physical properties of Haemophilus influenzae? (size, shape, gram, motility)

Answer 1

Small, gram-negative, non-motile, non-spore-forming bacilus/coccobacilus (pleimorphic)

Question 2

What are the two categories of Hemophilus influenzae?

Answer 2

Encapsulated (typeable) and Unincapsulated (non-typeable)

Question 3

What disease do encapsulated strains of H. influenzae cause?

Answer 3

acterial meningitis in young children

Question 4

What disease do unencapsulated strains of H. influenzae cause?

Answer 4

ear aches and respiratory disease

Question 5

Which type of encapsulated H. influenzae is the most important pathogen? What makes it different?

Answer 5

Type B has ribose instead of hexose in its polysaccharide capsule

Question 6

Is the capsule of encapsulated H. influenzae required for virulence? What purpose does it serve?

Answer 6

Yes, it is antiphagocytic

Question 7

What are the common clinical presentations of H. influenzae infection? (3 main types of infection with their presentations)

Answer 7

1. Nasopharyngitis often with otitis media. Can spread with bacteremia and meningitis
2. Epiglottitis with obstructive laryngitis - May be FATAL within 24hrs
3. Cellulitis and childhood pyarthrosis or pneumonia

Question 8

How does H. influenzae enter the body?

Answer 8

via respiratory tract generally through aerosols between children

Question 9

What does H. influenzae do to evade the immune system and prevent being expelled from the respiratory tract? (2 things)

Answer 9

1. Has an IgA protease

2. Induces ciliary stasis through decoration of LPS with host choline

Question 10

When is the most susceptible period in a person’s life (age)? How long does resistance remain low.

Answer 10

Most susceptible period between 6-12 months of age; resistance remains low for the first few years of life

Question 11

Is there a vaccine for Haemophilus influenzae? If so, what type of vaccine is it?

Answer 11

Yes, a conjugate capsular vaccine made with polyribosyl phosphate (PRP) linked to diptheria toxoid

Question 12

What are the treatment options for H. influenzae meningitis?

Answer 12

1. 3rd generation cephalosporin
2. Augmentin (ampicillin + clavulanate) - if the organism proves to be b-lactamase negative, treatment is switched to ampicillin

Question 13

What are the typical clinical manifestations of infections with NON-TYPEABLE H. influenzae? (2 common, 2 less common)

Answer 13

Common: 1. Otitis media 2. conjunctivitis
Less common 1. respiratory tract infections (usu. underlying respiratory condition) 2. meningitis (usu. a predisposing factor, important in neonates)

Question 14

Is haemophilus purely an extracellular pathogen?

Answer 14

No, it can invade mammalian cells

Question 15

Is there a vaccine for non-typeable H. influenzae? If so, what type is it?

Answer 15

No, there is no vaccine for non-typeable H. influenzae

Question 16

What are the treatment approaches for otitis media and sinusitis caused by H. influenzae?

Answer 16

1. Amoxicillin

2. Clavulanate or ceftriaxone

Question 17

How does non-typeable H. influenzae avoid killing by antibiotics?

Answer 17

It forms antibiotic resistant biofilms and can invade cells

Question 18

What type of growth conditions does H. influenzae require? (ie: does it need oxygen, are there any other factors it requires to be successfully grown in medium)

Answer 18

Faculative anaerobe

Requires growth factors X (hemin) and V (NADP), both present in blood

Question 19

What type of agar plate must be used to culture H. influenzae? Why?

Answer 19

Chocolate agar must be used because the mild heat used in preparation releases factors X and V from RBC

Question 20

How is the growth of staphylococcus related to the growth of H. influenzae?

Answer 20

Staph releases sufficient factor V to support growth of H. influenzae on blood agar plates

Question 21

What is the appearance of colonies of encapsulated H. influezae on medium?

Answer 21

Grow as smooth colonies

Question 22

If you suspect meningitis due to H. influenzae in your patient, how will you confirm your diagnosis? (What labs will you draw? What types of tests will you do?)

Answer 22

1. Draw blood and spinal fluid for culture
2. Streak spinal fluid on chocolate agar and incubate in CO2
3. Use immunofluorescence/immunoelectrophoresis to detect type b capsular Ag in spinal fluid

Question 23

What are the clinical manifestations of infection with Haemophilus ducreyi?

Answer 23

chancroid on genetalia

Question 24

What are the treatment options for a patient with a chancroid caused by Haemophilus ducreyi?

Answer 24

Sulfonamides, tetracycline, streptomycin

Question 25

What is the clinical manifestation of infection with Haemophilus aegypticus?

Answer 25

conjunctivitis, especially in hot climates (southern U.S.)

Question 26

What are the clinical manifestations of infection with Haemophilus parainfluenzae?

Answer 26

pharyngitis and bacterial endocarditis - major component of micro flora of oral and upper respiratory tract

Question 27

What major disease does Bordetella pertussis cause?

Answer 27

whooping cough

Question 28

What is the general physical structure of Bordetella pertussis? (size, gram, shape, oxygen utilization)

Answer 28

Small, gram-negative, coccobacillus, obligate aerobe

Question 29

In what animals is Bordetella pertussis found?

Answer 29

Only in humans

Question 30

What is the incubation period of B. pertussis?

Answer 30

7-10 days

Question 31

What clinical symptoms characterize the catarrhal stage of B. pertussis infection?

Answer 31

runny nose, sneezing, low-grade fever, and mild occasional cough (cold symptoms)

Question 32

What clinical symptoms characterize the paroxysmal stage of infection with B. pertussis?

Answer 32

bursts of coughing followed by high-pitched whoop and occasional vomiting with narrowing of the glottis following prolonged coughing fits

Question 33

How is B. pertussis introduced into the body?

Answer 33

via water droplets

Question 34

During the multiplication and toxin production stage of B. pertussis infection, do organisms invade the bloodstream?

Answer 34

No, they remain in the respiratory tract

Question 35

What are the 4 toxins produced by B. pertussis?

Answer 35

1. Pertussis toxin 2. Adenylate cyclase toxin 3. Dermonecrotic toxin 4. Tracheal cytotoxin

Question 36

What type of toxin is pertussis toxin and how does it act?

Answer 36

ADP-ribosylating toxin that affects a G-protein involved in inhibition of adenylate cyclase thus leading to an accumulation of cAMP Also affects the control of phospholipase C and ion channels

Question 37

What are the combined impacts of pertussis toxin?

Answer 37

lymphocytosis, sensitization to histamine, enhancement of insulin secretion

Question 38

How does adenylate cyclase toxin act and what is its effect?

Answer 38

It is activated by endogenous calmodulin. It catalyzes the production of cAMP from ATP Results in supraphysiologic concentrations of cAMP that impairs leukocyte function and may cause cell death

Question 39

Which Bordetella pertussis toxin is also known as "mouse lethal toxin" or "heat-labile toxin"?

Answer 39

Dermonecrotic toxin

Question 40

What does Dermonecrotic toxin cause?

Answer 40

It causes vascular smooth muscle contraction resulting in ischemic necrosis of lung tissue

Question 41

What does tracheal cytotoxin cause?

Answer 41

It causes ciliostasis, inhibits DNA synthesis, and ultimately kills tracheal epithelial cells

Question 42

What is the physical impact of the Pili of Bordetella pertussis on the host?

Answer 42

Pili mediate attachment to ciliated epithelial cells of the upper respiratory tract and cause diminished ciliary activity

Question 43

Other than Pili, what are the other 2 structures participating in colonization of Bordetella persussis?

Answer 43

filamentous hemagglutinin and pertactin

Question 44

Does the pertussis vaccine produce life-long immunity

Answer 44

No

Question 45

What is the main advantage of the DTaP vaccine over the DTP vaccine for pertussis?

Answer 45

The DTaP vaccine contains an acellular pertussis component so it is less likely to produce encephalopathy

Question 46

B. pertussis requires ____ _____ media for growth, so most clinical labs have switched to using PCR to detect organisms from washes of the nasal cavity.

Answer 46

very fresh

Question 47

What is the drug of choice for infection with B. pertussis? What are the alternatives?

Answer 47

Erythromycin; Alternatives: tetracycline, chloramphenicol

Question 48

What are the common diagnostic tests for B. pertussis?

Answer 48

Gram stain nasopharyngeal swab; direct anti-body test; culture on B-G