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29 Cards in this Set

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  • Back
Do mycoplasmas have cell wall & peptidoglycan?

What does this mean for effective antibiotics?
NO cell wall thus NO peptidoglycan

Because mycoplasmas lack a cell wall, they are resistant to beta lactams (penicillins, etc)
What do mycoplasms contain in their membranes?
Sterols (cholesterol)
How do mycoplasms grow? What kind of media?
grow by binary fission and can grow in cell free media.
What is the relative size of a mycoplasma?
smallest of all bacteria

tiny pleomorphic--easily deforms to fit thru tight places
What is the generation time for mycoplamsas?
1-6 hrs which is slow growth.
How are mycoplamsmas able to lyse erythrocytes on blood agar?

What effect does this have in vivo??
due to elaboration of hydrogen peroxide.

This phenomenon can cause CYTOTOXICITY in vivo as well.
What type of parasite is mycoplasma in vivo? In cell culture?
in vivo--primarily extracellular parasite

in cell culture--commonly intracellular
How is Mycoplasma pneumoniae transmitted?
inhalation of contaminated aerosols, nasal secretions
Where does Mycoplasma pneumoniae colonize? What is its time of incubation>
• It colonizes the epithelial cells of the upper respiratory tract and has a prolonged incubation period of 2-3 weeks.
How are the cilia inhibited?

What type of cells are destroyed and how?

What does this allow for?
The bacterium inhibits the function of the cilia in the respiratory tract.

P1-adhesin protein-interacts w/sialated glycoproteins of epithelial cells.

Epithelial cells are destroyed by HYDROGEN PEROXIDE production leading to NECROSIS of the tissue.

This can allow the lower respiratory tract to be contaminated.
What causes cough as a result of mycoplama pneumoniae infection?
Destruction of the cilia and epithelial cells are responsible for the persistent cough.
Besides pneumonia, what other problems can mycoplama pneumoniae cause?
Can you use gram stain to determine mycoplama pneumoniae?
No, no cell wall!!
What age group commonly gets Mycoplasma pneumoniae?
The disease is very common in school age children 5-15
What is mycoplasmas major antigenic determinant?
glycolipids--might cross react w/ human tissue
Name 3 ways mycoplama pneumoniae can be determined in the laboratory.
• Complement fixation (or Elisa)
• Cold Agglutinins
• Culture
What will agglutinate in cold agglutination?

What constitutes cold?
IgM Ab against erythrocyte I Ag.

clump at 4 C
Is clumping by cold agglutination reversible?
What are the 2 hypotheses regarding Ab against erythrocyte I Ag?
1. molecular mimicry--Ag on bacterial surface is similar to the I Ag

2. I Ag is modified by the mycoplasma to become MORE antigenic
What's the problem with the combination of sickle cell anemia and mycoplasma pneumoniae?
People who have a disorder like sickle cell anemia are already more likely to have their erythrocytes deform and clump in the small capillaries.

Infection w/ Mycoplasma pneumoniae can lead to even more obstruction of these capillaries and result in necrosis of that tissue
Where are specimens obtained for culture of mycoplasma pneumoniae?

What must the media contain?

What do colonies look like?
throat or bronchial washings

media must contain sterol

colonies look like mulberries
What are two mycoplasmas that are sexually transmitted?
Ureaplasma urealyticum

Mycoplasma hominis
What type of surfaces do Ureaplasma urealyticum or
Mycoplasma hominis
mucosal surfaces of the genitourinary tract
If a child recieves Ureaplasma urealyticum or
Mycoplasma hominis from their infected mother how long might the child have symptoms?
Up to 2 years of age
How does colonization result?
sexual contact
What disease can be caused by M. hominis? In adults? In children? In normal mothers after childbirth?
Pelvic Inflammatory Disease ( PID), pyelonephritis, and postpartum fever

Children: neonatal meningitis and brain abscesses.

occasionally normal mothers can develop arthritis of sudden onset after child birth w/ isolation of M. hominis
What does U. urealyticum require?
metabolized urea and requires it for growth
What disease can U. urealyticum cause?
nongonococcal urethritis
What is the group, Mycoplasma fermentans, incognitans and penetrans, thought to be implicated in?
HIV --although association is contraversial