Antibiotics Flashcards Preview

Year 1 Microbiology > Antibiotics > Flashcards

Flashcards in Antibiotics Deck (22):
1

Antimicrobial therapy relies on what principle tenet?

Selective toxicity

2

What contributes to antibiotic resistance?

Genetic mutation and/or acquisition of genetic elements from other bacteria carrying resistance genes

3

What are the mechanisms of antibiotic resistance?

1. Breakdown2. Chemical modification 3. Alteration4. Altered permeability, decreased influx or increased efflux5. Lack of target

4

What is bacteriostatic activity?

Level of antimicrobial activity that INHIBITS growth

5

What is the MIC?

1. Minimum inhibitory concentration2. Lowest concentration of antibiotic that inhibits growth

6

What is bactericidal activity?

Level of antibiotic that KILLS

7

What is the MBC?

1. Minimum bactericidal concentration2. Lowest concentration of antibiotic that kills 99.9%

8

What tests can give you the MIC?

1. Disk diffusion assay (circles)2. E-test (leaves)3. Broth culture

9

What are characteristics of cell wall active antibiotics?

1. Disrupts peptidoglycan synthesis2. Effective against actively dividing bacteria

10

What are characteristics of membrane active antibiotics?

1. Disrupts or interferes with membrane integrity / synthesis2. Effective against resting and actively dividing bacteria

11

How do B-lactams inhibit cell wall synthesis?

1. Bind to PBPs or other transpeptidases (cover active serine site)2. Prevents addition of another peptidoglycan sheet to growing wall

12

How is B-lactam resistance conferred?

1. Mutation so that B-lactams can no longer bind to active serine site of PBPs2. Pumped out of periplasmic space3. Altered permeability involving porins

13

How does vancomycin inhibit bacterial growth?

1. Recognizes and binds to two D-ala residues on peptide chains2. Prevents peptide chains from interacting properly with transpeptidase3. Cross links cannot be formed

14

How are bacteria resistant to vancomycin?

D-ala residue replaced by a D-lactate

15

How does bacitracin inhibit bacterial growth?

1. Inhibits cycling of peptidoglycan to outer leaflet2. Double phosphorylated bactoprenol builds up and cannot be used by cell

16

What are characteristics of tetracyclines?

1. Bacteriostatic2. Bind 30S subunit3. Broad spectruum

17

What are characteristics of aminoglycosides?

1. Generally bactericidal2. Bind 30S subunit3. Oxygen dependent4. Effective only against aerobic organisms

18

What are characteristics of macrolides?

1. Bind 50S ribosome2. Used as an alternate for individuals with penicillin allergy

19

What are characteristics of quinolones?

1. Bactericidal2. Inhibits DNA replication, recombination, and repair

20

What are characteristics of rifampin and rifabutin?

Bind to DNA dependent RNA polymerase and inhibits initiation of RNA synthesis

21

What are characteristics of metronidazole?

Reduced by bacteria = toxic compounds that damage DNA

22

What are characteristics of antimetabolites?

1. Target folate metabolism2. Sulfonamides, trimethoprim