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Unit 6: Micro > Haemophilus and Bordetella > Flashcards

Haemophilus and Bordetella Flashcards

1
Q

Cellular characteristics of Haemophilus influenzae?

A
  • Gram (-)
  • Non motile
  • Non-spore forming
  • Only grows on chocolate agar with Factors X and V
  • Respiratory droplets
  • Two forms - encapsulated and unencapsulated
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2
Q

Characteristics of high pathogenicity strain of H. influenzae?

A

Polysaccharaide capsule

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3
Q

Which type of H. influenze causes the worse diease?

A

Type B (Hib)

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4
Q

What is the target of the vaccine for H.influenzae?

A

The Hib capsule of polyribosyl ribitol phosphate

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5
Q

What is the target of the vaccine in NTHi?

A

Vaccine does not cover unencapsulated strains

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6
Q

How is H. influenzae similar to N. meningitidis?

A

Capsule fns in immune evasion

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7
Q

Describe Hib pathogenesis?

A
  1. Colonization of resp. mucosa via IgA protease
  2. Once estab. in resp. mucosa, invades bloodstream
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8
Q

What determines severity of Hib illness?

A

Magnitude and Duration of bacteremia

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9
Q

When is the peak risk for Hib infection?

A

6 mo to 1 yr - mother’s Ab wane, child can’t raise strong defense

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10
Q

Describe the NTHi pathogenesis

A
  1. NTHi utilizes pili, attachment proteins and IgA protease to invade
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11
Q

What patients are particular susceptible to NTHi?

A
  1. Patient’s with CF b/c bug can easily create a biofilm
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12
Q

Disease caused by H. influenzae

A
  1. Menigitis
  2. Cellulitis
  3. Otitis media and sinusitis
  4. Epiglottitis - Cherry Red epiglottis
  5. Septic arthritis
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13
Q

Dx procedure for Hib epitlottitis?

A

On exam, cherry red epiglottis is seen along with progressive respiratory difficulty, inability to swallow. Once airway secured, lateral neck radiograph is taken

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14
Q

What patients are NTHi associated with?

A

Neonates and postpartum women

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15
Q

What type of NTHi is particularly virulent?

A

Biotype 4

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16
Q

Procedure for H. influenzae Dx?

A

Culture on chocoalte agar with factors X and V; Growth on factor only agar is sufficient for Dx

17
Q

Tx for H. influenzae meningitis?

A

Ceftriaxone and in children > 2 mo, add Dexamethasone

18
Q

Tx for H. influenzae Upper Respiratory infection?

A

Amoxicillin + clavulanate or trimethoprim+sulfamethoxazole

19
Q

Primary preventive method for H. influenzae?

A

Vaccine early!

20
Q

Cellular characteristics of Bortedella Pertussis?

A
  • Encapsulated
  • G (-)
  • Human-restricted
21
Q

Characteristics of Pertussis disease?

A
  • Whooping cough
  • Highly contagious
22
Q

Pathogenesis of B. pertussis?

A
  1. Filamentous hemagglutinin pilus attaches bac. to cilia of epithelial cells lining resp. tract
  2. Pertussis toxin A-B subunit ADP-ribosylator kills ciliated cells, and inhibits chemokine signal transduction = lymphocytosis
  3. Tracheal cytotoxin - Kills ciliated cells as well
23
Q

What allows B. pertussis to be so virulent?

A
  1. Kills ciliated cells allowing for further bac. growth
  2. Production of mucopurulosanguineous exudate compromising small airways
  3. Both allow for paroxysmal cough and spread via many aerosol droplets
24
Q

Pertussis Px?

A
  • Do bacteremia
  • Px good, complications minimal
  • Major complication comes from infants deprived of oxygen
25
Q

Typical presentation of pertussis?

A

Afebrile, dehydrated, Hx of incomplete/absent vaccination

26
Q

3 stages of pertussis?

A
  1. Catarrhal - Nonspecific upper resp. Syx: Congestion, sneezing, rhinorrea, maximally contagious
  2. Paroxysmal - Intense coughing: Series of hacking cough, copious mucus production, inspiratory whoop
  3. Convalescence: Free of bugs but fatigue and chronic cough because bugs killed ciliated cells
27
Q

How can whoop be absent in adults?

A

Adult airway is large and may not be as obstructed

28
Q

Lab tests for B. pertussis?

A
  1. Pronounced leukocytosis (70% lymphocytes)
  2. Bordet-Gengou agar - but bugs are fastidious
29
Q

Tx for Pertussis?

A

Macrolides, supportive care b/c of dead ciliated cells

30
Q

Pertussis management in infants

A

Supplemental O2, mucus suctioning

31
Q

Pertussis prevention?

A
  1. Acellular vaccine - genetically-inactivated Pertussi toxoid, filamentous hemagglutinin, pertactin, fibriae types 2 and 3 (Used in US)
  2. Killed vaccine - whole heat-killed, believed risk of encephalopathy
  3. 10 year boosters needed for either vaccine
32
Q

Tx for unvaccinated exposed individuals?

A

Erythromycin

Unit 6: Micro (13 decks)

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