E1- Bacterial Pneumonia II Flashcards
What are the most common pathogens of HAP?
Pseudomonas aeruginosa*
Stapholococcus aureus
Klebsiella pneumoniae
Is Pseudomonas aeruginosa gram positive or gram negative? What shape?
Gram negative bacillus
What type of environments does Pseudomonas aeruginosa like?
Wet envrionements (cut flowers, food, sinks, toilets, dialysis equipment, disinfectants)
What color is Pseudomonas aeruginosa?
Blue-green
Pyoverdin, pyocyanin
What is unique about Pseudomonas aeruginosa?
Non-fermenting
What can Pseudomonas aeruginosa use as a terminal electron acceptor?
Nitrate
What kind of pathogen is Pseudomonas aeruginosa?
Opportunistic, rarely infects healthy individuals
What are the five virulence factors of Pseudomonas aeruginosa?
Adhesins Alginate capsule Pyocyanin Exotoxin A Elastases
What virulence factors of Pseudomonas aeruginosa is important for cyclic fibrosis patients?
Alginate capsule
Inhibits mucocilary escalator
How does pyocyanin act as a virulence factor in Pseudomonas aeruginosa?
Catalyze ROS and causes tissue damage
What elastases does Pseudomonas aeruginosa have? How do they work?
LasA and LasB
Work synergistically to degrade elastin (30% of the lung tissue is elastin)
What diseases can Pseudomonas aeruginosa cause?
Pneumonia (HAP)*
Urinary tract
Eye, ear, skin
Second leading cause of infection in burn pts
Common cause of death in cystic fibrosis pts
Sepsis
What population commonly gets chronic and recurrent Pseudomonas aeruginosa infections in the respiratory tract?
Cystic fibrosis pts
How is Pseudomonas aeruginosa pneumonia (HAP) dx?
Gram stain
Culture
Why is treatment of Pseudomonas aeruginosa pneumoniae (HAP) difficult?
Notoriously resistant to abx (capsule)
Pts are typically immunocompromised
Acquisition of resistance mediators
Can you prevent a Pseudomonas aeruginosa infection?
No, you can only hope to contain it
Prevent contamination of sterile equipment
Prevent pt to pt spread
What are the common pathogens that cause atypical pneumoniae?
Legionella pneumoniae
Mycoplasma pneumoniae
Chlamydophila pneumoniae
What disease can mycoplasma pneumoniae cause?
Atypical CAP
What is unique about mycoplasma pneumoniae?
No cell wall/peptidoglycan
What abx can you not use to tx mycoplasma pneumoniae? Why?
Beta lactams
They do not have a cell wall
How does atypical CAP caused by mycoplasma pneumoniae present?
Non productive cough that lasts 1-2 months Fever (not usually in children <5) Crackles Headache Chest pain Non specific rash
Does mycoplasma pneumoniae infection lead to long lasting immunity?
No, relapses are common
How is mycoplasma pneumoniae transmitted?
Person to person via respiratory droplets
How does mycoplasma pneumoniae attach to the respiratory epithelium?
Via attachment organelle leading to the development of ciliostasis, allowing the bacteria to colonize
What does Mycoplasma pneumoniae release that damages the epithelial layer?
H2O2
What is ciliostasis and how does it work?
Damage to the ciliated epithelium (paralysis)
Halts the mucociliary escalator, preventing the host from clearing the bacterium from the airway
Bacterium colonized
How is mycoplasma pneumoniae atypical pneumoniae dx?
CXR, culture, serological testing
Is Chlamydia pneumoniae gram positive or negative? What shape?
Gram negative
Coccus
What type of pathogen is Chlamydia pneumoniae?
Obligate intracellular parasite
What is the infectious stage of Chlamydia pneumoniae called?
Elementary bodies
What is the intracellular stage of Chlamydia pneumoniae called?
Reticulate bodies
How does atypical pneumoniae caused by Chlamydia pneumoniae present?
Generally asymptomatic or mild illness in adults
Persistent non productive cough and malaise for weeks to months
How is Chlamydia pneumoniae transmitted?
Person to person via respiratory droplets
What causes illness from a Chlamydia pneumoniae infection?
Tissue destruction during bacterial replication and the associated inflammatory response
Does infection with Chlamydia pneumoniae provide long lasting immunity?
No
What is the most effective tool for dx Chlamydia pneumoniae?
Serology
MIF test looks for IgM and IgG
Is Legionella pneumoniae gram positive or negative? What shape?
Gram negative bacillus
What species of Legionella pneumoniae causes majority of human infections?
L. Pneumohila serotype 1
What diseases can Legionella pneumoniae cause?
Pontiac fever
Legionnaires disease
How does Pontiac fever present?
Fever, chills, malaise, myalgia, headache, NO sign of pneumonia
Self limited illness
Sxs last for 2-5 days
Resolved without tx
How does legionnaires disease present?
Fever, chills, non productive cough, headache, GI/neuro sxs
Severe, acute atypical pneumonia with a high mortality rate
What causes death in legionnaires disease?
Shock or respiratory failure
Where does Legionella pneumoniae grow?
Aquatic environments
What does Legionella pneumoniae use as hosts?
Amoeba
How is Legionella pneumoniae transmitted?
Aerosolized biofilms (no person to person transmission)
Where does growth of Legionella pneumoniae occur in humans?
Alveolar macrophages
How is Legionella pneumoniae dx?
Culture is gold standard (buffered charcoal yeast extract)
Rapid test for antigen in the urine (only detects serotype 1)
