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M1 Micro Quiz 2 > Haemophilus and Bordetella > Flashcards

Haemophilus and Bordetella Flashcards

1
Q

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

A

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

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2
Q

What are the two categories of Hemophilus influenzae?

A

Encapsulated (typeable) and Unincapsulated (non-typeable)

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3
Q

What disease do encapsulated strains of H. influenzae cause?

A

acterial meningitis in young children

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4
Q

What disease do unencapsulated strains of H. influenzae cause?

A

ear aches and respiratory disease

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5
Q

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

A

Type B has ribose instead of hexose in its polysaccharide capsule

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6
Q

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

A

Yes, it is antiphagocytic

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7
Q

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

A
  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
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8
Q

How does H. influenzae enter the body?

A

via respiratory tract generally through aerosols between children

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9
Q

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

A
  1. Has an IgA protease

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

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10
Q

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

A

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

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11
Q

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

A

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

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12
Q

What are the treatment options for H. influenzae meningitis?

A
  1. 3rd generation cephalosporin
  2. Augmentin (ampicillin + clavulanate) - if the organism proves to be b-lactamase negative, treatment is switched to ampicillin
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13
Q

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

A

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)

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14
Q

Is haemophilus purely an extracellular pathogen?

A

No, it can invade mammalian cells

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15
Q

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

A

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

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16
Q

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

A
  1. Amoxicillin

2. Clavulanate or ceftriaxone

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17
Q

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

A

It forms antibiotic resistant biofilms and can invade cells

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18
Q

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)

A

Faculative anaerobe

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

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19
Q

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

A

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

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20
Q

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

A

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

21
Q

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

A

Grow as smooth colonies

22
Q

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?)

A
  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
23
Q

What are the clinical manifestations of infection with Haemophilus ducreyi?

A

chancroid on genetalia

24
Q

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

A

Sulfonamides, tetracycline, streptomycin

25
Q

What is the clinical manifestation of infection with Haemophilus aegypticus?

A

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

26
Q

What are the clinical manifestations of infection with Haemophilus parainfluenzae?

A

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

27
Q

What major disease does Bordetella pertussis cause?

A

whooping cough

28
Q

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

A

Small, gram-negative, coccobacillus, obligate aerobe

29
Q

In what animals is Bordetella pertussis found?

A

Only in humans

30
Q

What is the incubation period of B. pertussis?

A

7-10 days

31
Q

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

A

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

32
Q

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

A

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

33
Q

How is B. pertussis introduced into the body?

A

via water droplets

34
Q

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

A

No, they remain in the respiratory tract

35
Q

What are the 4 toxins produced by B. pertussis?

A
  1. Pertussis toxin
  2. Adenylate cyclase toxin
  3. Dermonecrotic toxin
  4. Tracheal cytotoxin
36
Q

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

A

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

37
Q

What are the combined impacts of pertussis toxin?

A

lymphocytosis, sensitization to histamine, enhancement of insulin secretion

38
Q

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

A

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

39
Q

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

A

Dermonecrotic toxin

40
Q

What does Dermonecrotic toxin cause?

A

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

41
Q

What does tracheal cytotoxin cause?

A

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

42
Q

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

A

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

43
Q

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

A

filamentous hemagglutinin and pertactin

44
Q

Does the pertussis vaccine produce life-long immunity

A

No

45
Q

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

A

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

46
Q

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

A

very fresh

47
Q

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

A

Erythromycin; Alternatives: tetracycline, chloramphenicol

48
Q

What are the common diagnostic tests for B. pertussis?

A

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

M1 Micro Quiz 2 (12 decks)

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