Introduction to Antimicrobials

Question 1

what are the four quadrants with antimicrobials?

Answer 1

gram positive anaerobes
gram positive aerobes
gram negative anaerobes
gram negative aerobes

Question 2

what do narrow spectrum antimicrobials target?

Answer 2

gram positive or gram negative

Question 3

what is the breakpoint MIC for susceptible?

Answer 3

<= 4 microgram/ml

Question 4

lower MIC for a given drug is __________, do not compare MICs between drugs

Answer 4

better

Question 5

what do bacteriostatic drugs do?

Answer 5

inhibit growth of bacteria

Question 6

what do bactericidal drugs do?

Answer 6

kill bacteria

Question 7

what does time vs concentration affect?

Answer 7

dosing regimen

Question 8

what do you want the peak concentration to be for concentration-dependent dosing?

Answer 8

multiple of MIC: more successful with higher dose at each administration

Question 9

what is the post antibiotic effect?

Answer 9

suppression of bacterial growth that persists after brief exposure of organisms to antimicrobials

Question 10

what are some things to consider with adverse event profiles?

Answer 10

can limit use to only a few days
monitoring for many potential side effects can make even cheap drugs quite expensive
drug allergies

Question 11

what does the Animal Medicinal Drug Clarification Act of 1994 allow?

Answer 11

extralabel drug use

Question 12

what are some drugs that are prohibited from extralabel use in food animals?

Answer 12

antimicrobial stewardship restrictions
carcinogens

Question 13

what is an antibiotic?

Answer 13

substance produced by microorganisms that acts against other microorganisms

Question 14

what are antimicrobials?

Answer 14

all agents that act against all types of microorganisms: bacteria, viruses, fungi, protozoa

Question 15

what are the modified four quadrants?

Answer 15

Staphylococcus
Streptococcus
gram negative
anaerobes

Question 16

what is an example of acquired resistance?

Answer 16

plasmids/chromosomal mutations encoding efflux pumps, altered drug targets, inactivation of drug, or altered permeability

Question 17

what are the ways to perform susceptibility testing?

Answer 17

kirby bauer disc diffusion
Etest
tube dilution

Question 18

what is the minimum inhibitory concentration?

Answer 18

lowest concentration that inhibits growth

Question 19

breakpoints are set for different body locations and are threshold concentrations that indicate _________________

Answer 19

susceptible
intermediate
resistant

Question 20

what does MIC stand for?

Answer 20

minimum inhibitory concentration

Question 21

are water soluble/polar antimicrobials often absorbed well from the site of administration?

Answer 21

no

Question 22

when might you prefer bactericidal drugs?

Answer 22

immunocompromised/immunosuppressed
bacterial meningitis
can mix bactericidal and bacteriostatic

Question 23

what does time-dependent dosing mean?

Answer 23

want to maintain as much time above bacterial MIC as possible during dosing interval
more frequent administration

Question 24

what does concentration mean with dosing regimen?

Answer 24

want peak concentration to be a multiple of the MIC
higher dose with each administration

Question 25

what are the proposed mechanisms of the post antibiotic effect?

Answer 25

slow recovery after reversible nonlethal damage to cell structures
persistence of the drug at binding site or within periplasmic space
need to synthesize new enzymes before growth can resume

Question 26

what does it mean that all medically important antimicrobials are required to be prescribed under a veterinary field directive with veterinarian oversight?

Answer 26

use of medically important drugs for growth promotion and feed efficacy no longer allowed
only disease prevention, control, and treatment