Antibiotics

Question 1

Bacteriostatic

Answer 1

inhibits growth but doesn’t kill

Question 2

Examples of bacteriostatic antibiotics

Answer 2

tetracyclines, macrolides, antimetabolites

Question 3

Tetracyclines

Answer 3

target bacterial ribosome (70S)
bind 30S subunit
broad spectrum

Question 4

Macrolides

Answer 4

target bacterial ribosome (70S)
binds to 50S subunit
used as an alternate for individuals with penicillin allergy

Question 5

Antimetabolities

Answer 5

target folate metabolism

Question 6

Bactericidal

Answer 6

kills the bacteria

used during invasive infections

Question 7

Examples of bactericidal antiboitics

Answer 7

B-lactams
Vancomycin
Aminoglycosides
Quinolones
Rifampin/rifabutin
Metronidazole

Question 8

B-lactam

Answer 8

inhibit cell wall synthesis

Binds beta lactamases and prevents enzymatic inactivation of b-lactam

Question 9

Vancomycin

Answer 9

attacks cell wall

1. In sensitive bacteria it recognizes and binds to two D-ala residues on the end of peptide chains
2. Present the peptide chains, prevents them from interacting properly with transpeptidase
3. Cross links can’t be formed

Question 10

Aminoglycosides

Answer 10

targets bacterial ribosome (70S)
binds to 30S subunit
oxygen-dependent
effective only against aerobic organisms

Question 11

Quinolones

Answer 11

inhibits DNA replication, recombination and repair

Question 12

Rifampin, rifabutin

Answer 12

binds to DNA depending RNA polymerase and inhibits initiation of RNA synthesis

Question 13

Metronidazole

Answer 13

reduced by bacteria

toxic compounds that damage DNA

Question 14

Sensitive infection

Answer 14

Infection may be treated with the dosage regimen of an antimicrobial agent recommended

Question 15

Intermediate infection

Answer 15

Infection may be treated in body sites where the drug are physiologically concentrated or when a high dosage of drug can be used

Question 16

resistant infection

Answer 16

Resistant isolates are not inhibited by the usually achieved concentrations of the antimicrobial

Question 17

General mechanisms of antibiotic resistance

Answer 17

Breakdown of an antibiotic
Chemical modification of an antibiotic
Alteration of the target
Altered permeability, decreased influx or increased efflux
Lack of target

Question 18

Empiric therapy

Answer 18

treatment while waiting for lab results (broad)

Question 19

Targeted therapy

Answer 19

refined treatment (narrow spectrum)

Question 20

How to prevent antibiotic resistance

Answer 20

only prescribe for bacterial infections
Maintain a therapeutic dose for a prolonged period of time
Combinatorial therapy
Antibiotic prophylaxis

Question 21

Who might need antibiotic prophylaxis

Answer 21

immunocompromised pts
surgical pts
those with exposure to certain high risk pathogens

Question 22

Minimum inhibitory concentration

Answer 22

lowest conc. of antibiotic that inhibits growth

Question 23

minimum bactericidal concentration

Answer 23

lowest conc. of antibiotic that kills 99.9% of bacteria

Question 24

Kirby Bauer Test

Answer 24

relies on antibiotic impregnated discs that are dropped onto a bacteria growth media that has bacteria spread across the agar surface. You measure the zone of clearing (zone of inhibition) around the disc. In doing this you are measuring the MIC.