Bacterial Nutrition

Question 1

Treponema Pallidum

Answer 1

Some bacteria grow only in living animas

• Causes Syphillus
• Needs to be grown in rabbit testicles

Question 2

Mycobacterium Leprae

Answer 2

Some bacteria grow only in living animals

• Causes leprosy
• Can be grown in mice or armadillo

Question 3

Three techniques to isolate organisms

Answer 3

Enrichment - has only the min reqs needed for growth
Selective - Selects growth of some while inhibiting growth of others
Differential - Other orgs can also grow, but it highlights a specific org. ex with EMB, only lactose fermenters stain black while non lactose fermenters can grow but look clear

Question 4

Eosin Methylene Blue (EMB)

Answer 4

Promotes Enteric Gram - Rods ie Enterobacter
Inhibits Gram +
Lactose Fermenters appear purple or metallic green

Question 5

Blood Agar

Answer 5

Not Selective
Hemolysis patterns seen
Promotes growth of many bacteria

Question 6

Mannitol Salt

Answer 6

Pink, Has high salt solution that a lot of bacteria can’t survive in.
Selects for Staph (Gram +)
Mannitol Fermentation is Yellow (Golden Staph)

Question 7

MacConkey Agar (MAC)

Answer 7

Promotes Gram - (Enterobacter, Serratia, Klebsiela)

Lactose Fermentation turns pink

Question 8

Beta Hemolysis

Answer 8

looks a yellow clear zone around the colonies

Pathogenic

Question 9

Alpha hemolysis

Answer 9

Normal Flora

Question 10

Bacteroides Fragilis

Answer 10

Obligate Anaerobe that cannot survive in presence of O2

Common in abdominal abscesses

Question 11

What two critical enzymes to Obligate Anaerobes Lack

Answer 11

Superoxide Dismutase & Catalase

High O2 tension can be used to treat infections with these bugs

Question 12

Pseudomonas Aeruginosa

Answer 12

Obligate Aerobe that causes nosocomial infections

Requires O2

Question 13

Bacillus Anthracis

Answer 13

Obligate Aerobe used in bioterrorism

Question 14

Clostridium Tetani

Answer 14

Obliage Anaerobe that causes tetanus

Question 15

Why is O2 required for obligate Aerobes?

Answer 15

They lack PFK, phosphofructose kinase
Cant make enough E from glycolysis alone
Make triose phosphates using Pentose Shunt
Can only offset the O2 deficit by Ox-Phos

Question 16

What Element is critical for all bacteria

Answer 16

Iron
It is in S containing compounds, as well as E carriers
Most Fe in Fe3+ state, can only use Fe2+
Bacteria have made Fe Transport systems

Question 17

What is a Siderophore

Answer 17

Its a Fe3+ Specific Ligand that bind bacterial membrane receptors to bring in the Fe3+ that will then be reduced to Fe2+ inside the bacterium

Question 18

Difference btwn E. Coli & Shigella Dysenteriae

Answer 18

E. Coli:
-Can ferment lactose
-Normal flora of the gut
-Resistant to Acid
Shigella
-Cant ferment lactose
-Not normal flora, indicates disease
-Low acid secretion (in malnutrition) predisposes to Shigella infection

Question 19

Diff btwn E. Coli & Enterobacter Aerogenes

Answer 19

Enterobacter:
-Gram - Rod
Produces Acetoin
Normally present in field water
E. Coli:
-Gram - Rod
Doesn't produce Acetoin
Indicative of Sewage Contamination

Question 20

What organism converts pyruvic acid to ethanol?

Answer 20

Yeast

Question 21

How can some bacteria make ethanol?

Answer 21

By converting pyruvate–>Acetyl CoA–>Acetylaldehyde–>Ethanol

Question 22

What are the two monomers for peptidoglycan?

Answer 22

N-Acetyl Glucosamine (NAG) & N-Acetyl Muramic Acid (NAM)

NAG makes NAM

Question 23

How is NAM made from NAG?

Answer 23

NAG + PEP = NAM.

This is blocked by Fofsomycin

Question 24

What does NAM require in order to be complete?

Answer 24

The addition of 5 Amino Acids. This is NAM pentapeptide

This step is blocked by Cycloserine

Question 25

What does Fofsomycin and Cycloserine antagonize, respectively?

Answer 25

PEP to block NAM synthesis | D-Alanine to prevent AA addition to NAM

Question 26

What are the three process required for making peptidoglycan?

Answer 26

Pep Monomer Ext of the Chain Cross Linking of glycan strands

Question 27

Extension of Pep Chain

Answer 27

NAG & NAM pentapeptide are linked in alternating chain | This is blocked by bacitracin

Question 28

Crosslinking (Vertical) of Pep layers

Answer 28

This is how the "thickness" of the peptidoglycan wall is achieved. In gram - there is only one layer so there is no cross linking. In gram + there multiple layers cross-linked This is inhibited by many Anitbx such as Beta Lactams (penicillin, cephalosporins) and vancomycin

Question 29

What is the enzyme needed to X-Link Pep layers?

Answer 29

Transpeptidase | This is where the antibx attack to prevent crosslinking

Question 30

``` Which class of bacteria have a thicker cell wall? Who is more restrictive? ```

Answer 30

Gram + have a thicker cell wall, but the outer membrane of gram - bacteria is more restrictive

Question 31

What are the 3 phases of bacterial growth

Answer 31

Lag, Exponential or Log & Stationary

Question 32

Describe the Lag Phase

Answer 32

This is the phase where protein synthesis is occuring. It takes a moment for the bacteria to get ready to start dividing

Question 33

Describe the Exponential or Log Phase

Answer 33

This is the phase where the bacteria divide rapidly. It also the time when the patient can get very sick very quickly so it may be wise to treat with an Antibx right away before getting Blood Cx results.

Question 34

Describe the Lag Phase

Answer 34

This is the phase where the bacteria has run out of nutrients and can no longer support division. This can mean death of the host.

Question 35

Doubling Time for Bacterial Growth tD

Answer 35

This is the mean generation time, and its the time it takes for the bacteria to double itself. If this time is small, then the bacteria grows very fast.

Question 36

Instantaneous Growth Rate for Bacteria (alpha)

Answer 36

Basically a faster growth rate means a shorter doubling time. So the larger the the growth rate, the faster it grows and the shorter the doubling time

Question 37

Exponential Growth Rate of Bacteria (u)

Answer 37

The larger it is the faster it grows