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Bacteriology Lectures > Bordetella, Haemophilus & Legionella > Flashcards

Bordetella, Haemophilus & Legionella Flashcards

1
Q

Bordetella organism type and shape

A

Gram negative coccobacillus, encapsulated Non-motile fastidious growth requirements

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2
Q

______ is associated with virulent strains of Bordetella

A

hemolysis

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3
Q

Bordetella stages (3)

A

Catarrhal - mild fever,cough Paroxysmal - Severe cough, lymphotoxicity results in leukocyte proliferation Convalescent - 45 days, cough is less severe

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4
Q

Bordetella spread and detection

A

droplet spread (highly contagious) CATARRHAL stage is the most contagious, making it hard to detect before it spreads!

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5
Q

Bordetella epidemiology

A

mainly kids getting it confers immunity 3 year cycles of incidence

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6
Q

4 reasons for US outbreaks of Bordetella

A

–Increased reporting (better surveillance) –Increased bacteral Ptx produced by strains –Antigen target of vax has changed –Not enough boosters given

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7
Q

Two virulence factors of Bordetella

A

Filamentous Hemagglutinin + Ptx Toxin

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8
Q

Filamentous hemagglutinin pathogenicity

A
  • Allows bacteria to bind to glycoprotein receptor on ciliated epithelial cells
  • **Phagocytosed without MQ activation**
  • Causes ciliary stasis of mucociliary escalator (not able to sweep up bacteria out of URT)
  • Aided by pili, pertactin, and Ptx
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9
Q

Ptx pathogenicity

A
  • AB5 toxin
  • Contains five B parts that bind to ganglioside specifically present in ciliated cells and phagocytes
  • The A subunit ADP ribosylates an inhibitory G protein
    • Keeps adenyl cyclase ACTIVE (increased cAMP)
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10
Q

What are the other 4 pathogenicity factors for Bordetella (not FH or PTx)

A
  1. Calmodulin-dependent adenyl cyclase
  2. Dermonecrotic toxin (T3SS)
  3. Tracheal cytotoxin - soluble peptidoglycan
  4. LPS (Lipids A and X)
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11
Q

Bordetella vaccine type and dose

A

Acellular (onloy surface proteins)

Vax given three times before 1 y.o. (5 times total)

Cocooning strategy for vaccination?

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12
Q

Can antibiotics be used for Bordetella control?

A

Yes!

Erythromycin / Azithromycin

*effective only if given in the catarrhal stage

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13
Q

Other bordatella

A

B. Parapertussis

  • contains cryptic ptx operon that is NOT expressed (less severe)
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14
Q

H. influenzae shape and structure

A
  • Gram negative
  • Coccobacillus (short)
  • Some have a typable capsule
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15
Q

H. influenzae growth media and appearance

A
  • the capsulated forms iridescent on BHI agar
  • Chocolate blood agar
  • Satellite colonies on Blood agar + Staph
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16
Q

H. influenzae requires _____ for growth

A

Heme (factor X)

NAD (Factor V)

17
Q

How are H. influenzae capsules typed (when they’re able to be typed)?

A

Quellung reaction

  • Types a-f
  • most infectious strains are type B (HiB)
18
Q

H. influenzae clinical presentation

A

different in babies, children, and adults!

Fetal = stillbirth if before 24 weeks

Children = Menigitis and Otitis Media (may be primary to meningitis). May cause epitglottitis or conjunctivitis.

Adults = non-typable forms, may cause PNA

19
Q

The “big three” for acute otitis media

A

H. influenzae

Strep pneumoniae

Moraxella catarrhalis

20
Q

Examination sign for epiglottitis

A

“Thumb sign” on radiograph

21
Q

H. influenzae is the major cause of ….

A

community acquired PNA in the US that requires hospitalization

22
Q

H. influenzae carrier rate, spread, and mortality

A
  • 75% for non-typable (only 3% for typable)
  • Spread via droplets
  • HiB meningitis is 90% fatal if not treated in time
23
Q

H. influenzae pathogenic factors

A
  1. adhesion pili and proteins (allow uptake and IC growth)
  2. IgA protease
  3. LOS (kinda like Neisseria)
  4. T-cell activation by soluble PG
  5. Poly-Ribosylribitol Phosphate (PRP) Capsule (the main one!)
    1. allows capillary and CNS invasion
24
Q

H. influenzae vaccine structure

A

Type B PRP

  • Conjugated to diphtheria toxoid for children older than 15 months
  • Conjugated to other proteins for children under 15 months
25
Q

Does AOM always require treatment? What agents are used?

A

No! 80% will resolve on own.

  • Amoxycillin (eardrops)
  • 3rd-gen Cephalosporins can be used,but may cause diarrhea
  • Rifampin is used for prophylaxis for meningitis in epidemic setting (b/c it crosses the BBB!)
26
Q

Other haemophilus

A

H. ducreyi

  • Chancroid
  • Ragged soft genital ulcer
  • Spread as STD
    • Contributes to spread of HIV d/t open lesion
  • Africa prevalence
  • Treatment = oral Bactrim or Macrolides
27
Q

Legionella Organism shape and growth characteristics/media

A
  • Gram negative Rod
  • Pleomorphic
  • Fastidious growth
    • Requires Iron + Cysteine
    • Needs High humidity
    • Slow growth on buffered charcoal yeast extract
28
Q

Legionella gram stain

A

Basic fuchscin must be used as a counterstain, because the unique unbranched fatty acids don’t stain well

29
Q

Legionella clinical presentation (diseases)

A

(most are ASYMPTOMATIC!)

  1. Pontiac Fever
    1. Highly infectious, mild flu-like disease for 1-2 days
  2. Legionnaires’ Disease
    1. Acute PNA
    2. Consolidation and Fibrin deposition in multiple foci, usually in LOWER parts of the lung
30
Q

Risk factors for Legionnaires disease

A

elderly (>55)

  • Smoking, emphysema, lung cancer
  • Bronchitis
  • Immunosuppressant drugs
31
Q

Most common overall bug for community acquired PNA

A

Strep Pneumo

(H influenzae is only number one for those cases which require hospitalization)

32
Q

Clinical presentations that favor Dx of legionella

A
  • Hyperacute
  • Septic shock
  • White cell count >15k
  • Lobar consolidation
33
Q

Legionella epidemiology

A

–Distributed in water and soil (city tap water)

–Can invade and parasitize amoeba and flagellated protozoa

–Forms FILM near standing water

  • Cooling towers, shower heads
  • Amoeba can be a reservoir
34
Q

Legionella transmission

A

Mechanically aerosolized droplets are inhaled by humans

NOT TRANSMISSIBLE from human > human

35
Q

Legionella pathogenic factors (4)

A
  • MQ-specific adhesion pili
  • Types 2 and 4 secretion system
    • T4SS secretes AnkB effector - interferes with microtubule based transport = no formation of phagolysosome
  • Pathogen mediated endocytosis
    • Mq coils one pseudopod around bacterium many times
  • release Blebs of LPS from outer membrane

*grows in macrphages by preventing Phagolysosome fusion (via AnkB)

36
Q

Legionella detection

A

Urine antigen test

37
Q

Legionella control

A

decontaminate source of droplets with Bleach and Superheating to at least 75 degrees Celsius

38
Q

____ may cause increased risk for Legionellosis

A

TNFa blockers

39
Q

Treatment for Legionnaires disease

A

Macrolides

  • Erythromycin
  • Azithromycin

Sometimes used in conjunction with fluoroquinolones)

Bacteriology Lectures (14 decks)

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