Flashcards in Basic Bacteriology 2, Gram positive bacterial Structure and Peptidoglycan in Human Disease Deck (37)
A microbe that is gram positive, beta hemolytic, cocci and sensitive to bacitracin is likely _. What is its main virulence factor?
Group A strep
Regarding case presentation 2, a fever that rises quickly to 104 and remains above 103 for 3 days and associated with significant chest pain is likely caused by what type of microbe?
Regarding case presentation 2, a violent cough that yields rusty sputum (i.e. blood tinged) is likely caused by _
What is the microbe that causes whooping cough?
A gram positive diplococci, alpha hemolytic on blood agar plates, sensitive to optochin and make a large polysaccharide capsule is likely what organism?
What is the main organism responsible for pneumonia? What might you observed on xray?
A consolidated (pus filled) lobe of the lung (light gray lobe, vs black for air)
What make it possible for an individual to have recurrent infection with pneumonia over and over, even if an adequate immune response was mounted each time?
Streptococcus pneumoniae can have one of 85 different capsules, so immunity to one doesn't mean immunity to others
What is the drug used to treat the patient in case 2? The fever breaks on day 4, what is the likely cause?
That is when IgM peaks
Green cap meningitis is caused by _
What is the major host defense against bacteria found in neutrophils? What is the color associated with this enzyme? Why?
It contains iron, and green reflects the oxidation state of iron in damaged tissues
Gram positive bacteria is likely to have a haploid or diploid chromosome? What are 3 other sources of DNA found in gram positive bacteria?
Episomes (Plasmids or bacteriophages)
True or false, gram positive bacteria have a typical lipid bilayer
True, nothing strange here
What surrounds the typical bilayer of a gram positive bacteria? What are the building block (2)
Cross bridged peptidoglycan layer
N acetyl glucosamine and N acetyl muramic acid
What surrounds the peptidoglycan layer of gram positive bacteria? What is the purpose? (2) What is it usually made of?
Negatively charged capsule
- Repel host cells
- mimic host
_ has a capsule made of hyaluronic acid. This serves the dual purpose of being negatively charged and mimicing host. Why is this capsule not immunogenic?
Group A streptococci
Because people have a lot of hyaluronic acid in their group substance
Most gram positive bacteria have capsules made of polysaccharides. What is the exception? What is its capsule made of?
Poly D glutamic acid
What is an example provided of a microbe whose major virulence factor is its capsule? How does it accomplish this?
The capsule repels host cells enough for it to grow and multiple
Arrange the following in order of closest to the microbes DNA to fartherst
- peptidoglycan layer
- lipid bilayer
- negatively charged capsule
A typical gram positve bacterial cell wall is _ percent cross linked vs. _ percent for a gram negative cell wall
gram + is 75, ve 25% for gram -
What are the 2 components of the bacterial cell wall? Which is crosslinked within the cell wall? Which extends to the cell membrane? What about the gram positive outer membrane?
Lipotechoic acid - Extends to cell membrane
Techoic acid - crosslinked within the cell wall
Outer membrane doesnt exist is gram positive cells
What is an advantage for bacteria of having ther peptidoglycan be composed of D amino acids?
Humans don't recognize D amino acids, therefore cannot degrade them
What are 2 organisms that are able to produce O-acetylated peptidoglycan? What are the resulting illnesses?
Streptococci - rheaumatic fever (arthritis, carditis)
Neisseria - post-gonococcal arthritis
How does O-acetylated peptidoglycan cause disease in humans? Why?
Accumulates in joints and causes arthritis and inflammation
It is very hard to degrade, highly inflammatory
Why do doctors treat streptococcus pneumoniae meningitis with corticosteroids?
The inflammation produced by the o-acetylated peptidoglycan from the organisms is responsible for increased fatality
Proteins, techoic acids or lipotechoic acids that creat a fuzz layer on the surface of bacteria are known as _. The function of this structure is mainly _ (2)
Adhesion and antiphagocytosis
What is the main protein that forms the fimbrae of streptococcus pyogenes? How does it accomplish its protective activity?
It is antiphagocytic because it prevents the deposition of complement
What is the main protein that forms the fimbrae of staph aureus?
Ribitol techoic acid
What is the individual subunit of flagellae? What is the name of flagella that surround the bacteria? What is the name of flagella that are only on the ends of bacteria? What is the function of flagella on ends of bacteria?
Between rods and pathogenic cocci, which is most likely to have flagella?
Rods are more likely to have flagella