Bordetella, Haemophilus & Legionella

Question 1

Bordetella organism type and shape

Answer 1

Gram negative coccobacillus, encapsulated Non-motile fastidious growth requirements

Question 2

______ is associated with virulent strains of Bordetella

Answer 2

hemolysis

Question 3

Bordetella stages (3)

Answer 3

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

Question 4

Bordetella spread and detection

Answer 4

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

Question 5

Bordetella epidemiology

Answer 5

mainly kids getting it confers immunity 3 year cycles of incidence

Question 6

4 reasons for US outbreaks of Bordetella

Answer 6

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

Question 7

Two virulence factors of Bordetella

Answer 7

Filamentous Hemagglutinin + Ptx Toxin

Question 8

Filamentous hemagglutinin pathogenicity

Answer 8

• 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

Question 9

Ptx pathogenicity

Answer 9

• 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)

Question 10

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

Answer 10

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

Question 11

Bordetella vaccine type and dose

Answer 11

Acellular (onloy surface proteins)

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

Cocooning strategy for vaccination?

Question 12

Can antibiotics be used for Bordetella control?

Answer 12

Yes!

Erythromycin / Azithromycin

*effective only if given in the catarrhal stage

Question 13

Other bordatella

Answer 13

B. Parapertussis

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

Question 14

H. influenzae shape and structure

Answer 14

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

Question 15

H. influenzae growth media and appearance

Answer 15

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

Question 16

H. influenzae requires _____ for growth

Answer 16

Heme (factor X)

NAD (Factor V)

Question 17

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

Answer 17

Quellung reaction

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

Question 18

H. influenzae clinical presentation

Answer 18

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

Question 19

The “big three” for acute otitis media

Answer 19

H. influenzae

Strep pneumoniae

Moraxella catarrhalis

Question 20

Examination sign for epiglottitis

Answer 20

“Thumb sign” on radiograph

Question 21

H. influenzae is the major cause of ….

Answer 21

community acquired PNA in the US that requires hospitalization

Question 22

H. influenzae carrier rate, spread, and mortality

Answer 22

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

Question 23

H. influenzae pathogenic factors

Answer 23

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

Question 24

H. influenzae vaccine structure

Answer 24

Type B PRP

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

Question 25

Does AOM always require treatment? What agents are used?

Answer 25

No! 80% will resolve on own. * _Amoxycillin_ (eardrops) * _3^rd-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!)

Question 26

Other haemophilus

Answer 26

_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**

Question 27

Legionella Organism shape and growth characteristics/media

Answer 27

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

Question 28

Legionella gram stain

Answer 28

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

Question 29

Legionella clinical presentation (diseases)

Answer 29

(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

Question 30

Risk factors for Legionnaires disease

Answer 30

elderly (\>55) * Smoking, emphysema, lung cancer * Bronchitis * Immunosuppressant drugs

Question 31

Most common overall bug for community acquired PNA

Answer 31

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

Question 32

Clinical presentations that favor Dx of legionella

Answer 32

* Hyperacute * Septic shock * White cell count \>15k * Lobar consolidation

Question 33

Legionella epidemiology

Answer 33

--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

Question 34

Legionella transmission

Answer 34

Mechanically aerosolized droplets are inhaled by humans NOT TRANSMISSIBLE from human \> human

Question 35

Legionella pathogenic factors (4)

Answer 35

* **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)

Question 36

Legionella detection

Answer 36

Urine antigen test

Question 37

Legionella control

Answer 37

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

Question 38

\_\_\_\_ may cause increased risk for Legionellosis

Answer 38

TNFa blockers

Question 39

Treatment for Legionnaires disease

Answer 39

**Macrolides** * Erythromycin * Azithromycin Sometimes used in conjunction with fluoroquinolones)