Lecture 6

Question 1

what happens in anaerobic jar?

Answer 1

chem rxn remove all O2, gen. H2 and CO2

Question 2

what happen in candle jar?

Answer 2

5-10% cO2 after flame dies, some residual O2

Question 3

candle jar good for:

Answer 3

neisseria (prefer lower O2, req. CO2)

Question 4

how transport anaerobes?

Answer 4

anaerobic transport media

Question 5

types of culture media

Answer 5

simple and complex

Question 6

simple media good for:

Answer 6

grow bacteria have very basic nutr needs (eg. e. coli)

Question 7

what’s in simple media?

Answer 7

glucose+few essential minerals (NaCl)

Question 8

complex media good for:

Answer 8

bacteria that need pre-formed nutr for growth

Question 9

what’s in complex media?

Answer 9

additional nutr like protein, CHO, minerals

Question 10

best use simple or complex if not sure?

Answer 10

complex

Question 11

why can’t some bacteria not be grown on lab culture media?

Answer 11

unusual enviro niche, unusual growth factors

Question 12

this media has additives toxic to some org but not others

Answer 12

selective

Question 13

examples of selective media

Answer 13

sabouraud agar

Question 14

no inhibitors added to this media

Answer 14

differential media

Question 15

type of differential media

Answer 15

blood agar (hemolytic vs nonhemolytic)

Question 16

hemolytic has ____ around colonies

Answer 16

zone of clearing

Question 17

diagnose ___ with blood agar

Answer 17

streptococcus

Question 18

both selective and differential

Answer 18

MacConkey

Question 19

how is MacConkey selective?

Answer 19

bile salts and crystal violet inhibit growth gram positive

Question 20

how is MacConkey differential?

Answer 20

lactose and pH indicator (lactose metabolized turn red, if not, stay white)

Question 21

chem substance either kill bacteria or prevent from growing

Answer 21

antibiotics

Question 22

how antibiotic diff from antiseptics and disinfectants?

Answer 22

selective action against bacteria

Question 23

who came up with concept of selective toxicity?

Answer 23

Paul Ehrlich

Question 24

Erhlich developed:

Answer 24

salvarsan (arsenic)–>syphilus

Question 25

first of sulfa class of antibiotics

Answer 25

prontosil (leather dye)

Question 26

who observed penicillin?

Answer 26

Fleming

Question 27

most antibiotics are:

Answer 27

natural from soil microbes

Question 28

dose which is toxic to host / dose requried kill bacteria is :

Answer 28

TI (therapeutic index)-->higher the better

Question 29

Quinolones and Rifampin work against bacteria through this mechanism:

Answer 29

block DNA/RNA synth

Question 30

inactivates DNA gyrase so no supercoiling:

Answer 30

quinolones

Question 31

binds to RNA polymerase to block mRNA synth

Answer 31

Rifampin

Question 32

how do antibiotics block protein synth?

Answer 32

bind to bacterial ribosome

Question 33

sulfas affect bacteria thru this mechanism:

Answer 33

inhibition of metabolic paths

Question 34

blocks synth of bacterial folic acid by acting as competitive inhibitor (similar to PABA structure)

Answer 34

sulfa

Question 35

polymyxin B affect bacteria thru this mechanism:

Answer 35

disrupt bacterial cell mem by binding to phospholipid and inserting into membrane

Question 36

why polymyxin B used only externally?

Answer 36

poor selective toxicity

Question 37

beta-lactams affect bacteria thru this mechanism:

Answer 37

block PG synth (high TI!)-->bactericidal

Question 38

these act at diff steps during PG synth:

Answer 38

non-beta-lactams (cycloserine, bacitracin, vancomycin)

Question 39

why is static antibiotic + PG blocker antagonistic?

Answer 39

cuz PG blocker only act during PG synth, on cells metabolically active and dividing

Question 40

using antibiotics in combo called:

Answer 40

antibiotic cocktails

Question 41

sulfonamide+trimethoprim is ex. of:

Answer 41

synergism (act on diff parts of same biochem path)

Question 42

synergism allows:

Answer 42

broader spectrum of action, less toxic, less likely resistance