Bordetella pertussis, Haemophilus influenzae, Legionella pneumophila Flashcards
Describe the structure of Bordetella pertussis.
Small, G- Coccobacillus
Encapsulated
Non-motile
Bordetella pertussis is associated with _______ in virulent strains.
Hemolysis
Incubation time of Bordetella pertussis?
1-2 weeks
Three stages of Bordetella pertussis?
Catarrhal stage
Paroxysmal Stage
Convalescent Stage
Describe symptoms in the catarrhal stage of Bordetella pertussis infection.
Low grade fever, runny nose, worsening cough
Describe the clinical presentation of the paroxysmal stage of Bordetella pertussis infection.
Severe Cough – So prolonged/irritated that inhalazion is wheezy and vomiting occurs
Lymphotoxicity results in leukocyte prolif
Common name of Bordetella pertussis?
Whooping Cough
Describe the Bordetella pertussis convalescent stage.
Cough becomes less severe for about 45 days
“The Cough of 100 days”
Complications of Bordetella pertussis?
Bronchopneumonia
Encephalitis
How is Bordetella pertussis spread?
Respiratory droplets
Why is Bordetella pertussis so prone to spread?
It is highly contagious
It is rarely detected before spread
In what stage is Bordetella pertussis most contagious?
Catarrhal stage
Who is most prone to get Bordetella pertussis? Who is it most dangerous in?
Small Children
Most dangerous in small airway
Four causes of Bordetella pertussis?
Increased Surveillance
Increased Toxin Production
Vaccine targets few antigens
Low coverage of booster vaccine
Six virulence factors of Bordetella pertussis
Filamentus hemagglutinin Pertussis toxin Calmodulin-dependent adenyl cyclase Dermonecrotic Toxin Tracheal Cytotoxin LPS
What is the activity of filamentous hemagglutinin?
- Allows Bordetella pertussis to bind specifically to glycoprotein receptor on ciliated epithelial cells
- Aided by pertactin surface protein, pili, pertussis toxin
What is the clinical significance of filamentous hemagglutinin?
Ciliary stasis of mucociliary escalator
can’t sweep bacteria out of resp. tract
Describe the six parts of pertussis toxin.
5 B parts bind to ganglioside for ciliated cells
A part - ADP ribosylates an inhibitory G ptorein
What does ribosylating the inhibitory G protein in Bordetella pertussis cause problems
Prevents inactivation of adenyl cyclase (inc. cAMP)
Increases H2O secretion in respiratory tract
Difference between pertussis toxin and cholera toxin.
Pertussis locks in stimulated/active form
Cholera blocks the inhibitory form
Effect of calmodulin-dependent adenyl cyclase.
Additional ACase, only active in eukaryotic cells
Role of dermonecrotic toxin? Who secretes it?
Role Uncertain
Secreted by T3SS
What is tracheal cytotoxin? What does it do?
Soluble peptidoglycan residue
Kills ciliated epithelial cells
What two lipids are contained in LPS?
Lipid A and Lipid X (half of A)
How is Bordetella pertussis controlled?
DTap Vaccine 3 times before 1st birthday, boosters
How can Bordetella pertussis be treated? What stage must a patient be in?
Erythromycin/Azithromycin
Catarrhal Stage
Describe Bordetella parapertussis
Similar to whooping cough, less severe
Have cryptic ptx operon
Describe the physical structure ofHaemophilus influenzae
G- coccobacillus
Some have capsule
Difference between typable and non-typable Haemophilus influenzae?
Typable have capsule, non-typable do not
Why to culture and make apparent Haemophilus influenzae?
Capsulated forms irridescent on BHI agar
Two factors required for Haemophilus influenzae growth in culture?
Heme (Factor X)
NAD (Factor V)
What happens to Haemophilus influenzae grown on “chocolate” blood agar?
“Satellite” colones will develop
How are Haemophilus influenzae typed?
Quellung reaction into type a-f
Add Ab that recognize, capsule gets bigger under microscope
What type are most infectious strains of Haemophilus influenzae?
B
How is Haemophilus influenzae spread?
Enters via URT mucosa
Effect of Haemophilus influenzae infection in utero before 24 weeks
Stillbirth
Effect of Haemophilus influenzae in children?
Meningitis
Acute otitis media
Frequency of bacterial meningitis in the US? % fatal?
4500
15%
Top Five Overall Causes on Meningitis?
S. pneumoniae - 58% Group B Strep - 18% N. miningitidis - 14% H. influenzae - 7% Listeria monocytogenes - 4%
Most common cause of meningitis in newborns?
GBS
Top three causes of meningitis in kids?
S. pneumoniae
N. miningitidis
H. influenzae
Most common cause of meningitis in teens?
N meningitidis
Most common cause of meningitis in adults?
S. pneumoniae
Most common cause of meningitis in elderly?
S. pneumoniae
What three bacterial strains are most prone to cause acute otitis media?
Haemophilus influenzae
Strep pneumoniae
Moraxella catarrhalis
How does Haemophilus influenzae tend to present in adults?
Pneumonia, Sinusitis, Epiglottitis
Sign seen in radiograph of a Haemophilus influenzae patient?
Thumb sign of the epiglottis
Top two causes of bacterial pneumonia?
Streptococcus pneumoniae
Haemophilus influenzae
How is Haemophilus influenzae spread?
via droplets
Especially common in daycare centers
Untreated Haemophilus influenzae meningitis is ___% fatal
90
Why is Haemophilus influenzae typically not a huge problem for adults?
They’re probably already immune
Describe Haemophilus influenzae pathogenesis
- Adhesion pili allow uptake and intracellular growth
- IgA protease prevents IgA detection
- LOS makes less immunogenic/easily killed
- T cell activation by soluble PG
What is the main virulence factor of Haemophilus influenzae (seen in Type B)
poly-ribosylribitol phosphate (PRP) capsule
it allows capillary/CNS invasion
What is the Haemophilus influenzae vaccine made of?
PRP conjugated to diptheria toxoid
Why might you avoid antibiotics for Haemophilus influenzae?
80% of the time, resolves on its own in 3 days
92% success with amoxycilin, but 3rd gen
What other drug can you use to treat Haemophilus influenzae? Why wouldn’t you?
Caohalosporins
Diarrhea as side effects
Describe the presentation of Haemophilus ducreyi.
Ragged soft ulcer on genitals
How is Haemophilus ducreyi spread?
STD
Haemophilus ducreyi requires what to grow?
Factor V
Where is Haemophilus ducreyi most prevalent? How is it treated?
Africa
SxT or Macrolides
Describe the physical structure of Legionella pneumophila?
G- Rods
Variable Length, Pleomorphic
Things required for the growth of Legionella pneumophila
Fe, Cysteine
High Humidity
How is Legionella pneumophila plated?
Buffered charcoal yeast extract agar
Three ways in which Legionella pneumophila manifests?
Asymptomatic
Pontiac Fever
Legionnaire’s Disease
Describe Pontiac Fever seen in Legionella pneumophila.
Highly infectious
Mild flu-like malaise that runs its course in a day or 2
Describe Legionnaires’ Disease in Legionella pneumophila?
Acute pneumonia with high fever
Consolidation and fibrin deposition in multiple foci
(usually lower parts of lungs)
Most likely group to contract Legionnaire’s Disease?
Elderly men over 55
Risk factors for Legionnaire’s Disease (3)?
Smoking, Emphysema, Lung Cancer
Bronchitis
Immunosuppressant Drugs
Top 5 most common pathogens to cause community-acquired Pneumonia.
Streptococcus pneumoniae Hemophilus influenzae Staphylococcus aureus Gram-negative bacilli Legionella bacilli
Most likely place to find Legionella pneumophila?
Fresh water and Soil
58% of outbreaks in city tap water
Form films in continually standing water
Legionella pneumophila survive in….
Amoeba
How does Legionella pneumophila tend to be spread?
mechanically aerosolized droplets inhaled
NOT transmissable person-to-person
Describe the pathogenesis of Legionella pneumophila.
- Macrophage-specific adhesion pili
- Type II and Type IV (Dot/Icm) (4 secretes AnkB - stops lysosome fusion to phagosome)
- Pathogen mediated endocytosis (coiling phagocytosis)
- Grow in macrophages by preventing fusion
- Can release PS blebs from outer membrane
What does AnkB do?
Stops Lysosome fusion to phagosome
How to detect Legionella pneumophila?
Urine Antigen Test
How to decontaminate Legionella pneumophila?
Bleach + Superheating
How to treat Legionella pneumophila?
Macrolides: erythromycin/azithromycin
