Antimicrobial Pharmacology

Question 1

antibiotic

Answer 1

substances produced by microorganisms intended to suppress other microorganisms

naturally produced

Question 2

antimicrobial

Answer 2

all agents that kill or inhibit growth of all types of microorganisms
- antibacterial/fungal/viral

naturally or therapeutically produced

Question 3

therapeutic triad

Answer 3

host, drug, organism

three considerations for achieving sufficient concentration of appropriate antimicrobial at the target site to eradicate the organism and minimize adverse effects and resistance development

Question 4

goal of antimicrobial treatment

Answer 4

concentration of antibacterial agent at site of infection must inhibit pathogen and remain below level that may be toxic to host

Question 5

components of appropriate antimicrobial use

Answer 5

• presence of bacteria
• select appropriate antimicrobial
• dose to achieve therapeutic concentrations
• use at a time when likely to prevent/treat disease
• route of administration
• duration of therapy
• modify therapy as needed

Question 6

susceptibility testing

Answer 6

establishes drug sensitivity and determines effective antibiotic concentration

Question 7

minimum inhibitory concentration (MIC)

Answer 7

lowest concentration that prevents visible growth

indicates concentration required to target the organism at the target site

Question 8

minimum bactericidal concentration (MBC)

Answer 8

lowest concentration of antimicrobial that will kill an organism

Question 9

bacteriostatic

Answer 9

ability to inhibit growth of an organism

MBC > 4xMIC

relies on hosts own immune system to clear the infection completely - only use in immunocompetent animals

Question 10

bactericidal

Answer 10

ability to kill an organism

MBC < 4xMIC

does not rely on hosts own immune system

Question 11

broad spectrum

Answer 11

effective against a wide range of microorganisms

more likely to kill natural microbiome

Question 12

narrow spectrum

Answer 12

effective against a limited range of bacteria

Question 13

what are the targets of antimicrobials

Answer 13

things/processes that are necessary for cell survival

Question 14

PK/PD relationship

Answer 14

host factors vs drug factors

determines drug efficacy

Question 15

PK

Answer 15

drug concentration that the organism is exposed to throughout dosing interval

depends on Cmax and AUC

Question 16

PD

Answer 16

response of infecting organism to the drug

depends on MIC

Question 17

absorption

Answer 17

drug administration into the body

• IV
• topical
• oral

Question 18

when are IV antimicrobials used

Answer 18

critically ill patients or hard to reach organs

Question 19

when are topical antimicrobials used

Answer 19

drugs that are too toxic for systemic administration

Question 20

when are oral antimicrobials used

Answer 20

long term use
non hospitalized patients
target site is GIT

Question 21

are slow use formulations appropriate for antimicrobials

Answer 21

no - often won’t reach MIC

Question 22

distribution

Answer 22

getting the drug to the site of infection

Question 23

protected sites

Answer 23

areas that are difficult to reach with drugs
- organs w/ continuous capillaries
- CNS, eyes, prostate, lungs, intracellular

more lipophilic drugs are more likely to reach

Question 24

what are some local factors that affect pharmacokinetics

Answer 24

• pus, necrotic, infected tissue, cell debris
• cell material
• surgical implants
• acidic envionments

Question 25

elimination

Answer 25

mechanism of removing the drug from the body

Question 26

considerations regarding drug elimination

Answer 26

avoid drugs if the organ they rely on for elimination is diseased

Question 27

time dependent PK/PD

Answer 27

efficacy is best predicted by the time that concentrations remain above the MIC

T > MIC: activity continues as long as concentration is greater than MIC

may require more frequent dosing intervals

Question 28

concentration dependent PK/PD

Answer 28

efficacy is best predicted by the ratio of Cmax/MIC or AUC/MIC

activity requires concentration to be above MIC

can be protective because there can be more time below MIC

may require longer dosing intervals

Question 29

post antibiotic effect (PAE)

Answer 29

the persistent suppression of bacterial growth when blood levels of drug are lower than the MIC, even in the absence of host immune response

allows longer dosing intervals because effect continues when concentration < MIC

Question 30

combination therapy

Answer 30

using multiple antimicrobial drugs in a therapeutic regimen

avoid unless required

Question 31

synergism

Answer 31

the drugs kill organisms through sequential pathways or independent mechanisms

Question 32

antagonism

Answer 32

the drugs make each other ineffective or directly inactivate each other

Question 33

host factors that influence antimicrobial therapy

Answer 33

• immunocompetence
• renal/hepatic function
• age
• species
• drug allergy

Question 34

mechanisms of antimicrobial resistance

Answer 34

1. inactivating enzymes that destroy the drug
2. decreased drug accumulation
3. alteration of drug binding site
4. development of alternative metabolic pathways