Basic Bacteriology 2, Gram positive bacterial Structure and Peptidoglycan in Human Disease

Question 1

A microbe that is gram positive, beta hemolytic, cocci and sensitive to bacitracin is likely _. What is its main virulence factor?

Answer 1

Group A strep

Super antigen

Question 2

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?

Answer 2

Bacteria

Question 3

Regarding case presentation 2, a violent cough that yields rusty sputum (i.e. blood tinged) is likely caused by _

Answer 3

Strep. pneumoniae

Question 4

What is the microbe that causes whooping cough?

Answer 4

Bordetella pertusis

Question 5

A gram positive diplococci, alpha hemolytic on blood agar plates, sensitive to optochin and make a large polysaccharide capsule is likely what organism?

Answer 5

Streptococcus pneumoniae

Question 6

What is the main organism responsible for pneumonia? What might you observed on xray?

Answer 6

Streptococcus pneumoniae 
A consolidated (pus filled) lobe of the lung (light gray lobe, vs black for air)

Question 7

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?

Answer 7

Streptococcus pneumoniae can have one of 85 different capsules, so immunity to one doesn’t mean immunity to others

Question 8

What is the drug used to treat the patient in case 2? The fever breaks on day 4, what is the likely cause?

Answer 8

Amoxacillin

That is when IgM peaks

Question 9

Green cap meningitis is caused by _

Answer 9

Streptococcus pneumoniae

Question 10

What is the major host defense against bacteria found in neutrophils? What is the color associated with this enzyme? Why?

Answer 10

Myeloperoxidase
Green
It contains iron, and green reflects the oxidation state of iron in damaged tissues

Question 11

Gram positive bacteria is likely to have a haploid or diploid chromosome? What are 3 other sources of DNA found in gram positive bacteria?

Answer 11

Haploid
Episomes (Plasmids or bacteriophages)
Transposons
Pathogenicity islands

Question 12

True or false, gram positive bacteria have a typical lipid bilayer

Answer 12

True, nothing strange here

Question 13

What surrounds the typical bilayer of a gram positive bacteria? What are the building block (2)

Answer 13

Cross bridged peptidoglycan layer

N acetyl glucosamine and N acetyl muramic acid

Question 14

What surrounds the peptidoglycan layer of gram positive bacteria? What is the purpose? (2) What is it usually made of?

Answer 14

Negatively charged capsule
- Repel host cells
- mimic host
Polysaccharides

Question 15

_ 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?

Answer 15

Group A streptococci

Because people have a lot of hyaluronic acid in their group substance

Question 16

Most gram positive bacteria have capsules made of polysaccharides. What is the exception? What is its capsule made of?

Answer 16

Bacillus anthracis

Poly D glutamic acid

Question 17

What is an example provided of a microbe whose major virulence factor is its capsule? How does it accomplish this?

Answer 17

Streptococcus pneumoniae

The capsule repels host cells enough for it to grow and multiple

Question 18

Arrange the following in order of closest to the microbes DNA to fartherst

• peptidoglycan layer
• lipid bilayer
• negatively charged capsule

Answer 18

lipid bilayer
peptidoglycan layer
capsule

Question 19

A typical gram positve bacterial cell wall is _ percent cross linked vs. _ percent for a gram negative cell wall

Answer 19

gram + is 75, ve 25% for gram -

Question 20

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?

Answer 20

Lipotechoic acid - Extends to cell membrane
Techoic acid - crosslinked within the cell wall
Outer membrane doesnt exist is gram positive cells

Question 21

What is an advantage for bacteria of having ther peptidoglycan be composed of D amino acids?

Answer 21

Humans don’t recognize D amino acids, therefore cannot degrade them

Question 22

What are 2 organisms that are able to produce O-acetylated peptidoglycan? What are the resulting illnesses?

Answer 22

Streptococci - rheaumatic fever (arthritis, carditis)

Neisseria - post-gonococcal arthritis

Question 23

How does O-acetylated peptidoglycan cause disease in humans? Why?

Answer 23

Accumulates in joints and causes arthritis and inflammation

It is very hard to degrade, highly inflammatory

Question 24

Why do doctors treat streptococcus pneumoniae meningitis with corticosteroids?

Answer 24

The inflammation produced by the o-acetylated peptidoglycan from the organisms is responsible for increased fatality

Question 25

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)

Answer 25

Fimbrae | Adhesion and antiphagocytosis

Question 26

What is the main protein that forms the fimbrae of streptococcus pyogenes? How does it accomplish its protective activity?

Answer 26

M protein | It is antiphagocytic because it prevents the deposition of complement

Question 27

What is the main protein that forms the fimbrae of staph aureus?

Answer 27

Ribitol techoic acid

Question 28

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?

Answer 28

Flagellin Peritrichous flagella Polar flagella Motility

Question 29

Between rods and pathogenic cocci, which is most likely to have flagella?

Answer 29

Rods are more likely to have flagella

Question 30

What are MSCRAMMs? What is their function? On what pathogen are they found? What is the main component of the capsule of this organism?

Answer 30

Microbial Surface Component Recongnising Adhesive Matrix Molecule Stick to host cells Streptococcus pyogenes Hyaluronic acid

Question 31

Is listeria monocytogenes gram positive or negative? Is it a cocci or rod? Does it have flagella or not? Are its flagella functional (i,e. is it motile)?

Answer 31

Gram positive Rod has flagella Functional, i.e. its motile

Question 32

Inert, heat and dryness resistant structures found in gram positive bacteria, produded when conditions are hostile are called _. What is the aerobic organism that produces this structure? What is the anerobic organism that produces this structure?

Answer 32

Spores Aerobic - Bacillus Anerobic - Clostridium

Question 33

What are the 2 major components of the spore coat that confer resistance?

Answer 33

Dipicollinic acid | Calcium

Question 34

What is generated when a gram positive bacteria is treated with enzymes (e.g. lysozyme) that causes it to lose its cell wall? Can this cell wall be regenerated?

Answer 34

Protoplast | Cell wall cannot be regenerated

Question 35

What are polybetahydroxybutyric acid granules?

Answer 35

They are energy storage granules seen in some bacteria

Question 36

What is the organism that causes tetanus? Under which condition is this organism likely to produce its toxins, the vegetative state or the spore form? What common sports item does this organism resemble?

Answer 36

Clostridium tetani Vegetative state Tennis racket

Question 37

When observing bacillus under a scope, the rods look like they have dark staining ends and a clear central region. In what region are the spores likely to be found, ends or center?

Answer 37

The clear center