Lecture 7 Flashcards
Shape and stain of B. pertussis
Coccobacilli
Capsulated
GramNeg
Is B. pertussis motile
No
Virulent strains of B. pertussis is associated with what
Hemolysis
Incubation period of B. pertussis
1-2 weeks
Catarrhal stage of B. pertussis
Low grade fever
Runny nose
Worsening cough
Paroxysmal stage of B. pertussis
Severe cough “Whooping”
Lymphotoxicity (body makes excess WBCs because this bug is associated with hemolysis)
Convalescent stage of B. pertussis
Less severe cough lasting ~45 days
B. Pertussis complications
Bronchopneumonia
Encephalitis
How does B. pertussis spread
Respiratory droplets
Highly contagious
What is most contagious stage of B. pertussis?
Catarrhal stage
Why is B. pertussis most dangerous in small children?
They have small airways
What are two main reasons B. pertussis is resurging
Most adults are not reimmunized
We’ve changed the vaccine from whole-cell to acellular vaccine (whole-cell had LPS and 1% had reaction)
What is the true way of gaining immunity to B. pertussis
Having the infection once
What are the six virulent factors of B. pertussis
Filamentous hemagluttinin (Fha) Pertussis toxin Calmodulin-dependent adenyl cyclase Dermnonecrotic toxin Tracheal cytotoxin LPS
Filamentous hemagluttinin (Fha) does what?
Allows B. pertussis to bind to ciliated epithelial cell
How does B. pertussis toxin work?
AB toxin similar to cholera toxin
B part binds to ciliated cells and phagocytes
A part ADP-ribosylates G-protein-inhibitory
Prevents inactivation of adenyl cyclase
What is the treatment for B. pertussis
Use erythromycin but it must be administered in the catarrhal stage
What is the unique signature of LPS in B. pertussis?
Contains Lipid A and lipid X
X is the unique signature
What is one way to help confer B. pertussis immunity to an infant?
Immunize the mother prior to delivery
Dermonecrotic factor from b. pertussis is secreted from the pathogen in which manner?
T3SS
What to virulent factors from b. pertussis lead to prolonged cough?
Dermonecrotic factor
Tracheal cytotoxin
What is mechanism of tracheal cytotoxin released from b. pertussis
(Is a soluble peptidoglycan)
Kills ciliated epithelial cells
What is mechanism of calmodulin-dependent adenyl cyclase virulent factor from b. pertussis?
Additional increase of cAMP
remember that the AB toxin prevents the inactivation of adenyl cyclase
What is the main symptom of pertussis in an adult?
Just a prolonged cough (1/5 of prolonged coughs due to b. pertussis).
Filamentous hemagluttinin from b. pertussis ultimately leads to what?
Phagocytosis in ciliated epithelium without activating macrophages
How do we diagnose b. pertussis?
Culture (this is a difficult method)
PCR (gold standard currently)
Antibody tests are not always effective
How does b. pertussis lead to ciliary stasis?
It has surface proteins pili and pertactin
What could be the benefit of administering antibiotics later in a pertussis infection?
It could help prevent the spread
Increased cAMP associated with b. pertussis leads to what?
cAMP increases fluid secretion into the lungs
When should antibiotics be administered for pertussis
If you’ve been exposed
If there is an outbreak
If you work with people that might be susceptible (old and young)
If you have infection in catarrhal stage
Appearance and stain of H. influenzae
Coccobacillus
GramNeg
What are the two forms of H. influenzae?
Typable (has a capsule)
Non-typable
How does capsulated H. influenzae look on BHI agar?
Iridescent
What does H. influenzae need to grow?
Factor V and X clotting factors (hemolysis is required for these)
How many forms of capsules are associated with H. influenzae
Types A-F
What is the most infectious capsule of H. influenzae
Type B
Kids typically have what form of H. influenzae?
Typable
What is the main concern for H. influenzae in children?
- Meningitis (often involves brain damage, hearing loss)
2. Otitis media
What are the big three for acute otitis media?
H. influenzae
Strep pneumonaie
Moraxella catarrhalis
Besides otitis media and meningitis, what are other conditions caused by H. influenzae in children?
Bacteremia
Pharyngitis
Bronchitis
Epiglottitis (spreads via tear duct-conjunctivitis)
Adults most often have what type of H. influenzae?
Non-typable
What are clinical conditions in adults caused by H. influenzae?
Pneumonia
Sinusitis
Epiglottitis
What does H. influenzae spread?
Respiratory droplets (highly contagious, communal settings)
Why has H. influenzae meningitis decreased?
We have a good vaccine for B-type (Hib)
How does H. influenzae adhere to cells?
Pili and proteins
What is the main virulence factor of H. influenzae?
Poly-ribosyribitol phosphate (PRP) capsule
Allows invasion of capillaries and CNS
What are lesser virulence factors of H. influenzae?
IgA proteases
Lipooligosaccharides (LOS)
T-cell activation by soluple PG
What is a lesser form of B. pertussis?
B. parapertussis (less severe than whooping cough)
How do you make type B PRP (H. influenzae) vaccine effective?
In children > 15 months-conjugate to diphtheria toxoid
In children > 2 months-conjugate to other proteins
Antiobiotics for haemophilus
Most resolves in less than 3 days
Amox for OM
Cephalosporins for OM (increased risk diarrhea)
Rifampin for meningitis
Another common haemophilus bug and sypmtoms?
H. Ducreyi Ragged soft ulcer on genitals STD Requires factor V but not X Treat with oral SxT or Macrolides
Legionella pneumophila shape and stain
GramNeg
Rods with unique branched fatty acids
What do you have to use to stain branched fatty acids of legionella pneumophila
Fuchsin stain
What do legionella pneumophila need to grow?
Fe and cysteine
High humidity
On what medium does legionella pneumophila grow slowly on?
Buffered charcoal yeast extract sugar
What are the two clinical conditions caused by legionella pneumophila
Pontiac fever
Legionnaires’ Diease
Characteristics of pontiac fever
Highly infectious
Mild flu-like illness that lasts a few days
Legionnaires’ symptoms
Acute pneumonia with high fever
Consolidation and fibrin deposition in multiple foci, usually in lower lungs
What are the risk factors for Legionnaires?
> 55 year old male
Smoker (or emphysema or lung CA)
Bronchitis
Immunosuppresent drugs
What bug is most often implicated in community acquired pneumonia?
Streptococcus pneumoniae
Where is legionella pneumophila found?
Fresh water and soil
Films form in standing water (water towers, shower heads, some city water)
How can legionella pneumophila infect via other organisms?
Can parasitize amoeba and flagellated protozoa
Transmission of legionella pneumophila?
From mechanized aerolized water droplets (water vapor from shower head)
Not transmissible person to person
How do legionella pneumophila adhere?
Macrophage-specific adhesion pili
What secretion system does legionella pneumophila use?
Type IV (Dot/Icm)
What does legionella pneumophila secrete?
AnkX (type IV system) that interferes with m’ tubule based transport (no lysosome fusion to phagosome)
How is legionella pneumophila taken up by macrophages?
Secretes AnkX to induce macrophage endocytosis
Macrophage wraps bacteria with pseudopod many times
Bacteria can release LPS from outer membrane
How do you detect legionella pneumophila?
Urine antigen test
How do you decontaminate source of legionella pneuomophila?
Bleach
Superheating
What is treatment for legionella pneumophila?
Macrolides: erythromycin
Sometimes add quinolones
What type of receptor recognizes lipteichoic acid (GramPos)
TLR2:TLR6 (also recognizes zymosan on yeast)
What type of receptor recognizes LPS (GramNeg)?
TLR4:TLR4
MD2 and CD14 are also complexed here
What type of receptor recognizes unmethylated CpG-rich DNA on bacteria and viruses? Location in the cell?
TLR9
Endosomes
