Bordetella organism type and shape
Gram negative coccobacillus, encapsulated Non-motile fastidious growth requirements
______ is associated with virulent strains of Bordetella
hemolysis
Bordetella stages (3)
Catarrhal - mild fever,cough Paroxysmal - Severe cough, lymphotoxicity results in leukocyte proliferation Convalescent - 45 days, cough is less severe
Bordetella spread and detection
droplet spread (highly contagious) CATARRHAL stage is the most contagious, making it hard to detect before it spreads!
Bordetella epidemiology
mainly kids getting it confers immunity 3 year cycles of incidence
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
Two virulence factors of Bordetella
Filamentous Hemagglutinin + Ptx Toxin
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
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)
What are the other 4 pathogenicity factors for Bordetella (not FH or PTx)
- Calmodulin-dependent adenyl cyclase
- Dermonecrotic toxin (T3SS)
- Tracheal cytotoxin - soluble peptidoglycan
- LPS (Lipids A and X)
Bordetella vaccine type and dose
Acellular (onloy surface proteins)
Vax given three times before 1 y.o. (5 times total)
Cocooning strategy for vaccination?
Can antibiotics be used for Bordetella control?
Yes!
Erythromycin / Azithromycin
*effective only if given in the catarrhal stage
Other bordatella
B. Parapertussis
- contains cryptic ptx operon that is NOT expressed (less severe)
H. influenzae shape and structure
- Gram negative
- Coccobacillus (short)
- Some have a typable capsule
H. influenzae growth media and appearance
- the capsulated forms iridescent on BHI agar
- Chocolate blood agar
- Satellite colonies on Blood agar + Staph
H. influenzae requires _____ for growth
Heme (factor X)
NAD (Factor V)
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)
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
The “big three” for acute otitis media
H. influenzae
Strep pneumoniae
Moraxella catarrhalis
Examination sign for epiglottitis
“Thumb sign” on radiograph
H. influenzae is the major cause of ….
community acquired PNA in the US that requires hospitalization
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
H. influenzae pathogenic factors
- adhesion pili and proteins (allow uptake and IC growth)
- IgA protease
- LOS (kinda like Neisseria)
- T-cell activation by soluble PG
-
Poly-Ribosylribitol Phosphate (PRP) Capsule (the main one!)
- allows capillary and CNS invasion
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
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!)
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
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
Legionella gram stain
Basic fuchscin must be used as a counterstain, because the unique unbranched fatty acids don’t stain well
Legionella clinical presentation (diseases)
(most are ASYMPTOMATIC!)
-
Pontiac Fever
- Highly infectious, mild flu-like disease for 1-2 days
-
Legionnaires’ Disease
- Acute PNA
- Consolidation and Fibrin deposition in multiple foci, usually in LOWER parts of the lung
Risk factors for Legionnaires disease
elderly (>55)
- Smoking, emphysema, lung cancer
- Bronchitis
- Immunosuppressant drugs
Most common overall bug for community acquired PNA
Strep Pneumo
(H influenzae is only number one for those cases which require hospitalization)
Clinical presentations that favor Dx of legionella
- Hyperacute
- Septic shock
- White cell count >15k
- Lobar consolidation
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
Legionella transmission
Mechanically aerosolized droplets are inhaled by humans
NOT TRANSMISSIBLE from human > human
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)
Legionella detection
Urine antigen test
Legionella control
decontaminate source of droplets with Bleach and Superheating to at least 75 degrees Celsius
____ may cause increased risk for Legionellosis
TNFa blockers
Treatment for Legionnaires disease
Macrolides
- Erythromycin
- Azithromycin
Sometimes used in conjunction with fluoroquinolones)