Bordetella, Haemophilus & Legionella Flashcards Preview

Bacteriology Lectures > Bordetella, Haemophilus & Legionella > Flashcards

Flashcards in Bordetella, Haemophilus & Legionella Deck (39):
1

Bordetella organism type and shape

Gram negative coccobacillus, encapsulated Non-motile fastidious growth requirements

2

______ is associated with virulent strains of Bordetella

hemolysis

3

Bordetella stages (3)

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

4

Bordetella spread and detection

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

5

Bordetella epidemiology

mainly kids getting it confers immunity 3 year cycles of incidence

6

4 reasons for US outbreaks of Bordetella

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

7

Two virulence factors of Bordetella

Filamentous Hemagglutinin + Ptx Toxin

8

Filamentous hemagglutinin pathogenicity

  • 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

9

Ptx pathogenicity

  • 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)

10

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

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

11

Bordetella vaccine type and dose

 

Acellular (onloy surface proteins)

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

Cocooning strategy for vaccination?

12

Can antibiotics be used for Bordetella control?

Yes!

Erythromycin / Azithromycin

 

*effective only if given in the catarrhal stage

13

Other bordatella

B. Parapertussis

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

14

H. influenzae shape and structure

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

15

H. influenzae growth media and appearance

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

16

H. influenzae requires _____ for growth

Heme (factor X)

NAD (Factor V)

17

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

Quellung reaction

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

18

H. influenzae clinical presentation

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

The "big three" for acute otitis media

H. influenzae

Strep pneumoniae

Moraxella catarrhalis

20

Examination sign for epiglottitis

"Thumb sign" on radiograph

21

H. influenzae is the major cause of ....

community acquired PNA in the US that requires hospitalization

22

H. influenzae carrier rate, spread, and mortality

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

23

H. influenzae pathogenic factors

  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

H. influenzae vaccine structure

Type B PRP

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

25

Does AOM always require treatment? What agents are used?

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

Other haemophilus

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

Legionella Organism shape and growth characteristics/media

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

28

Legionella gram stain

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

29

Legionella clinical presentation (diseases)

(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

Risk factors for Legionnaires disease

elderly (>55)

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

31

Most common overall bug for community acquired PNA

Strep Pneumo

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

32

Clinical presentations that favor Dx of legionella

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

33

Legionella epidemiology

--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

Legionella transmission

Mechanically aerosolized droplets are inhaled by humans

NOT TRANSMISSIBLE from human > human

 

35

Legionella pathogenic factors (4)

  • 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

Legionella detection

Urine antigen test

37

Legionella control

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

 

38

____ may cause increased risk for Legionellosis

 

TNFa blockers

39

Treatment for Legionnaires disease

Macrolides

  • Erythromycin
  • Azithromycin

Sometimes used in conjunction with fluoroquinolones)