EX2 Effects of Antibiotics on Bacteria - Bailey Flashcards Preview

SP14 Microbiology > EX2 Effects of Antibiotics on Bacteria - Bailey > Flashcards

Flashcards in EX2 Effects of Antibiotics on Bacteria - Bailey Deck (33):
1

In 1920, Alexander Flemming described the potential usefulness of what

penicillin

2

In 1940, Ernst Chain and Howard Flory demonstrated the water and effectiveness of penicillins in what

humans (in WWII)

3

What are the two mode of action of antibiotics

bactericidal; kill bacteria
bacteriostatic; reduce metabolic activity

4

An ideal antibiotic has what four things

broad spectrum of activity
would not induce resistance
high therapeutic index
selective toxicity

5

This is the ratio between a toxic dose and effective dose; if the ratio is 1, then you need a toxic dose to eradicate the microbe

high therapeutic index

6

What four things are unique to microbes that help achieve selective toxicity

cell wall
enzymes for replication, transcription, and translation
essential metabolites
ribosomes

7

What are the 5 ways that antibiotics inhibit bacteria

cell wall synthesis
membrane function
protein synthesis (ribosomes)
antimetabolites
inhibition of nucleic acids

8

What are some places of antibiotic inhibition involving cell wall synthesis

NAG binding with NAM
NAG/NAM elongtation
formation of NAM side chains
transport of chain to periplasmic space
peptide chain cross linking

9

How does penicillin disrupt cell wall synthesis

prevents the formation of peptide bonds between side chains

10

What structure does penicillin use to disrupt cell wall synthesis

D-alanine; penicillin is cleaved instead of the D-alanine causing substrate overload, and cleaved penicillin is more toxic

11

What is used to disrupt cell membrane function

polymyxin B sulfate by binding to LPS layer, disrupting it

12

What is targeted in inhibiting protein synthesis

ribosome

13

What are some of the places of antibiotic inhibition involving ribosomes

prevention of 50S and 30S binding
prevention of tRNAs to bring AAs to 30S
change configuration of ribosome to change the tunnel
prevent 30S and 50S from binding to mRNA start site
prevent elongation of AA chain

14

What can be an issue with inhibitors of DNA replication

they bind to DNA are are too toxic too use

15

What is the one antibiotic that binds to DNA, being covered to an active from by anaerobic microbes

metronidazole

16

Antibiotics like nalidxic acid and quinolines affect what

DNA gyrase

17

Antibiotics like rifamycin inhibit this

RNA polymerase

18

Hows does sulfanilamide act as a antimetabolite

PABA (para-aminobenzoic acid) forms folic acid in bacteria, and the sulfanilamide disrupts the formation

19

Penicilin, clindamycin, and cephalosporins are typically used to treat what

odontogenic infections
(clindamycin also treats abscesses)

20

metronidazole and tetracyclines are typically used to treat what

peridontitis (metronidazole also treats abscesses)

21

What are the three steps in the action of antibiotics

drug penetrates the envelope
transport into cell
drug binds to target

22

What are the three mechanisms of drug resistance

synthesis of enzymes that inactivate the drug
prevent of access to the target site
modification of the target site

23

What are the two ways in which a bacteria can prevent an antibiotic form accessing the target site

inhibiting uptake
increasing secretion of the drug

24

Some bacteria can produce enzymes which do what to penicillin

break the β-lactam ring; inactivating the bond

25

How to antibiotics enter the cell

through porins

26

Bacteria change the structure of porins, which increase the resistance to which antibiotics

tetracyclines and quinolones

27

Some bacteria develop this to remove antibiotics from themselves (all classes of bacteria have this

efflux pumps; pump the drug out

28

How does a microbe modify the target site

modify enzyme activity
alteration of metabolic pathway (high affinity, etc.)

29

How does antibiotic resistance spread

chromosome associated resistance (mutations)
plasmid mediated resistance
rapid spread resistance

30

What is the main reason it is important to finish the course of an antiobiotic

high resistant bacteria take a longer time to die, if you stop taking the antibiotic prematurely, then the number of antibiotic resistant bacteria increases

31

What three things are used to combat an antibiotic resistant pathogen

synergism (2+ antibiotics)
antagonism
indifference

32

What are the drawbacks to administering an antibiotic cocktail

failure to eliminate pathogen; superinfection
synergistic toxicity (multiplied)

33

True or False
Antibiotics are effective against all microbes

False; not viruses, fungi, etc.