2 Bacteriology 1

Question 1

What are the types of prokaryotic pathogens?

Answer 1

Bacteria, mycoplasma (bacteria w/o cell wall), rickettsia (bacteria that must live inside host cell)

Question 2

What are the eukaryotic microbial pathogens?

Answer 2

Fungi

Question 3

Define bacteriophage

Answer 3

A virus that infects bacteria

Question 4

What is a plasmid, and what types of plasmids are there?

Answer 4

Extra-chromosomal bacterial DNA.
R-plasmids: antimicrobial resistance plasmids
Virulence plasmids: virulence factors

Question 5

What is an R plasmid?

Answer 5

An antimicrobial resistance plasmid

Question 6

Gram ____ bacteria have a thick peptidoglycan layer and will stain ____.

Answer 6

Positive; purple

Question 7

Gram ______ bacteria have a thin peptidoglycan layer and will stain ____.

Answer 7

Negative; pink

Question 8

What type of bacteria typically have an outer membrane?

Answer 8

Gram -

Question 9

Bacteria that require reduced oxygen are called _______

Answer 9

Microaerophilic aerobes

Question 10

What is MacConkey agar selected for?

Answer 10

Gram - enterobacterales (rods) and some non-enterobacterales (bile salts inhibit a lot of other bacteria)

Question 11

What are siderophores?

Answer 11

A ‘virulence-lifestyle’ protein that helps microorganisms bind iron from the environment to persist in the host.

Question 12

What are the major types of bacterial toxins?

Answer 12

Endotoxins and exotoxins

Question 13

What type of toxin is LPS, and what are its components?

Answer 13

Endotoxin; lipid a – biological action, core polysaccharide – structural link, carbohydrate O side chain – length determines virulence

Question 14

What kind of bacteria produces endotoxins and why can other types of bacteria not produce endotoxins?

Answer 14

Gram - bacteria, because it ONLY produced in the outer membrane

Question 15

What is the effect of LPS/endotoxins on the hosts’ tissues?

Answer 15

Inflammation

Question 16

What is the effect of bacterial exotoxins on the host cells?

Answer 16

Host cell damage or disruption of function

Question 17

What is a toxoid?

Answer 17

An inactivated exotoxin used in a vaccine.

Question 18

What are the three types of bacterial exotoxins?

Answer 18

A-B toxins (simple and compound), superantigens, and disorganizers of host cell membranes

Question 19

What is the function of the “B” component of an A-B toxin?

Answer 19

B is for Binding! Binds to the host cell receptor and determines toxin specificity.

Question 20

What is the function of the “A” component of an A-B toxin?

Answer 20

A is for Activity! Responsible for the enzymatic action and toxicity after translocation into the host cell

Question 21

What is the difference between a simple and complex A-B toxin?

Answer 21

A complex toxin has multiple B subunits.

Question 22

What are the two MOA’s of membrane disrupting exotoxins?

Answer 22

1. Channel into the host cell membrane and swell to cause cell/vacuole rupture
2. Enzyme that compromises phospholipid membrane integrity

Question 23

What is the MOA of superantigens?

Answer 23

Bridges MHC-II of macrophages and T cells outside of the antigen groove, causing MASSIVE T-cell stimulation.

Question 24

Why is the host response to superantigens dangerous?

Answer 24

MASSIVE release of cytokines, esp. IL-2 leading to fever, vomiting, shock

Question 25

T or F: only G+ bacteria have capsules.

Answer 25

Gram- AND Gram+ bacteria can have capsules

Question 26

What is the function of a bacterial capsule?

Answer 26

Inhibits complement fixation and phagocytosis

Question 27

In general, what kind of bacteria make spores?

Answer 27

Gram +

Question 28

What is the advantage of a bacteria forming spores?

Answer 28

They are metabolically inactive and extremely environmentally resistant so they can survive adverse conditions.

Question 29

What are the four ways that bacteria can acquire new genetic material?

Answer 29

Conjugation Transduction Transposition Transformation

Question 30

Describe conjugation.

Answer 30

Transfer of plasmids via sexual pilli.

Question 31

Describe transduction.

Answer 31

Genetic material is transferred via bacteriophages.

Question 32

Describe transposition.

Answer 32

Uptake of naked DNA.

Question 33

Describe transformation.

Answer 33

Transfer of mobile DNA.

Question 34

List each step of performing a Gram stain and include the purpose of each step.

Answer 34

1. Crystal violet - stains peptidoglycan 2. Iodine - fixes crystal violet to cells 3. Alcohol - decolorizes (removes crystal violet stain from gram negative bacteria and most of the stain from gram positive bacteria) 4. Safranin - counterstains the gram negative bacteria pink

Question 35

What are the differences between Gram staining and Diff-Kwik?

Answer 35

Gram staining is better for bacteria, whereas Diff-Kwik is better for WBCs/RBCs and cellular components. Gram stains appear purple and pink, whereas Diff Kwik is blue and pink.

Question 36

What are the four morphologies of bacteria microscopically?

Answer 36

Rods, cocci, coccobacilli (short rods), and filamentous (long rods)

Question 37

What color is yeast on Gram stains?

Answer 37

Variable shades of both pink and purple

Question 38

What type of agar is used to test hemolysis?

Answer 38

Blood agar

Question 39

What are the types and appearances of the results of a hemolysis test on blood agar?

Answer 39

Complete hemolysis - yellowing of agar Partial hemolysis - greening of agar Non-hemolysis - no change in agar

Question 40

Define alpha, beta, and gamma hemolysis.

Answer 40

Beta hemolysis - complete hemolysis by Streptococcus Alpha hemolysis - partial hemolysis by Streptococcus Gamma hemolysis - non-hemolysis by Streptococcus

Question 41

What reagents are used to stain spore-forming bacteria, and what is the function of each reagent?

Answer 41

Malachite green - stains spores dark green Carbol fuschin - counterstains vegetative bacteria pink

Question 42

What layers make up the bacterial envelope in G- and G+ bacteria?

Answer 42

BOTH - cell membrane, peptidoglycan layer G- only - outer membrane (contains LPS)

Question 43

What are exotoxins made of?

Answer 43

Protein