Legionella and Mycoplasma Flashcards
What is the general physical description of Legionella pneumophila? (gram, shape)
Gram-negative, pleomorphic rod
Does Legionella pneumophila grow intra or extracellularly?
It grows intracellularly
Where in nature is Legionella pneumophila most commonly found?
In the water of cooling towers, resides in free-living amoeba or free-living in biofilms
What is the principal symptom in serious cases of infection with Legionella?
atypical pneumonia
What is the more mild form of Legionella infection called?
Pontiac fever
How is infection with Legionella acquired?
airborne transmission from environmental contamination
Is Legionella communicable? (can you get it from an infected person)
No, it is only acquired from environmental sources such as stagnant water in air conditioning and heating units
What is the incubation period of Legionella?
2-10 days
What cellular reactions are characteristic of the early stage of infection with Legionella?
induction of apoptosis in macrophages and alveolar epithelial cells
What cellular reactions are characteristic of the second stage of infection with Legionella?
Necrosis induced by pore-forming activity in infected phagocytes
Is Legionella invasive?
Yes, it can disseminate from the lung and cause invasive disease
What type of medium can Legionella be grown on?
charcoal yeast extract with iron and cysteine
What is the test of choice for the diagnosis of Legionella infection?
Direct flourescent antibody test
In what samples would you detect Legionella antigens?
Urine samples
What should you keep in mind when testing antibody levels to Legionella in your patient’s blood?
Take 2 samples 3-6 weeks apart
What is the smallest replicating bacteria?
Mycoplasma pneumoniae
What structural feature sets Mycoplasma apart form all other bacteria? How does this impact antibiotic choice?
No cell wall so resistant to antibiotics that target the cell wall
Will mycoplasma grow on cell-free media?
Only if sterols and other nutrients are provided by yeast extract and animal serum.
Will mycoplasma grow on standard laboratory medium?
No
Is immunity from mycoplasma life-long?
No, may acquire the disease again after 5-10 years
What disease is caused by Mycoplasma infection?
atypical pneumonia with gradual onset
What is the difference between typical and atypical pneumonia seen on X-ray?
Typical has lobar arrangement, atypical does not and includes spotty points of infection
What are the 3 organisms that cause atypical pneumonia?
Legionella, Mycoplasma, Chlamydia pneumoniae
Do extrapulmonary infections occur from Mycoplasma infection? If so, what is the system affected?
Yes, CNS
How is mycoplasma transmitted?
By aerosols, usually from close playmates
What does Mycoplasma use to attach to respiratory epithelium? What does it do there?
Adhesins including P1 complex; induces cilliotosis (ciliostasis, right ??) resulting in necrosis
What does Mycoplasma produce that leads to oxidative damage and inflammation
hydrogen peroxide
How is Mycoplasma treated?
Antibiotics that interfere with protein synthesis such as macrolides and tetracyclines
Is there a vaccine for Mycoplasma? If so, what type is it?
No vaccine is available
What diagnostic tests are most effective for Mycoplasma?
PCR and cold agglutination with serum IgM antibodies
