Legionella Pneumophila Flashcards
Why did they call it as such?
Because there was a conventional legion in a hotel in Philadelphia where around 10% of them died of an unknown pneumonia.
Are they gram negative or positive?
They are gram negative
Are they motile? Spore forming?
they are nonmotile and non-spore forming
Are they aerobic, anaerobic or facultative anaerobes?
They are aerobic
How are they transmitted?
By inhalation from AC
By aspiration from heads of shower
From hospitals (nosocomial infections)
Where do bacteria go directly when they are acquired?
They go to alveoli
In which type of environments they like to live?
They live in moist and warm environments
What is the clinical presentation?
Pontiac fever
Legionnaire’s disease (related to pneumonia)
Which factors affect the pathogenesis?
- Age, as age increases cellular immunity decreases (Legionnaire‘s disease is never seen in youngsters)
- Immune status, mainly people with background cardiopulmonary diseases, or smokers
- Inoculum size
- Degree of exposure to the source i.e. how long we have been exposed to the shower heads
Which one is the milder outcome?
Pontiac fever
How does it occur?
It occurs in epidemic waves, anytime during the year
What’s the incubation period?
1 to 2 days like a cold or flu
What are the symptoms?
They are flu like symptoms
Is there a person to person spread? Do we need to have background predisposing factors to be infected?
There is no person to person spread except in a few cases
There is no need for a background predisposing factors
Is there bacteremia? Pneumonia?
There is no bacteremia
There is no pneumonia because it is related to the upper respiratory tract
What is the presentation of legionnaires disease?
It comes as: epidemics in late summer or fall, or sporadic i.e. nosocomial infections in people having a special surgical procedure, or endemic throughout the year
Do we need to have background predisposing factors to be infected?
There has to be an underlying pulmonary disease in order to be infected
To which part of the respiratory tract it is related?
It is related to the lower respiratory tract, upper respiratory tract manifestations are very rare or absent
Where do bacteria go once acquired?
To the lungs in the alveoli
How some of them resist killing by macrophages in alveoli?
By inhibiting the oxidative burst
What is the difference between this pneumonia and those caused by other bacteria?
Chest pain in this case will be more pronounced
What do we find in alveoli and bronchioles?
Large amount of solidified sputum that’s not expectorated
There is a thick mucus plugs with fibrin, RBCs, PMN and macrophages
Is it a systemic type of infection? M
Yes it is, it can spread via blood or lymphatic chain with activity of LPS
Where bacteria could be present after spread?
In intestines, liver, spleen, kidneys, lymph nodes, brain
