pharmacology 3

Question 1

minimum inhibitory concentrations (MIC)

Answer 1

lowest concentration of drug that inhibits visible bacterial growth
MIC90 concentration for inhibiting 90% of the bacteria

Question 2

Minimum bactericidal concentration (MBC)

Answer 2

the lowest concentration of a drug that kills 99.9% of bacteria

Question 3

mutant prevention concentration (MPC)

Answer 3

the concentration of the least susceptible single-step mutant
in theory, kills them all so mutant so they cant form

Question 4

bacteriostatic

Answer 4

stop bacteria from multiplying: don’t kill them
MBC much larger than MIC
elimination of infection requires host immune response
requires an immunocompetent patient

Question 5

bactericidal

Answer 5

kill bacteria if concentrations reach MBC for a certain period of time
MBC at or near the MIC
preferred for immunosuppressed animals
preferred for severely ill patients

Question 6

bactericidal antimicrobials are not always bactericidal

Answer 6

static at concentration below MBC
dose dependent
bacteria dependent
bacterial must be multiplying for cidial to work

Question 7

postantibiotic effect (PAE)

Answer 7

persistent drug effect
after plasma concentration decline below the MIC/MBC

Question 8

mechanisms of PAE

Answer 8

decreased virulence of bacteria
development of abnormal cell wall or septum
increased susceptibility to host defenses
persistence at site of infection
only occurs with some drugs and is bacteria-dependent

Question 9

pharmacokinetic-pharmacodynamic interaction

Answer 9

predict the success of antimicrobial therapies
relate concentration of drug to MIC of the pathogens
vary by class of drug
vary with each pathogen
drug-bug interaction

Question 10

time-dependent antibiotics

Answer 10

T>MIC
duration plasma concentration if above the MIC over 24 hours

Question 11

concentration dependent antibiotics

Answer 11

Cmax:MIC
ratio of the maximum plasma concentration to the MIC

Question 12

Concentration/time dependent antibiotics

Answer 12

AUC:MIC
ratio of the AUC.24 to the MIC

Question 13

narrow spectrum

Answer 13

implies activity against a limited subset of bacteria

Question 14

broad spectrum

Answer 14

implies activity against a wide range of bacteria
may include mycoplasma, rickettsia, and chlamydia

Question 15

spectrum of activity

Answer 15

tells you that the bacteria can be affected by antimicrobial

Question 16

aerobic bacteria

Answer 16

gram +
streptococci
staphylococci
gram -
respiratory pathogens
enteric pathogens

Question 17

anaerobic bacteria

Answer 17

gram +
gram -

Question 18

penicillins

Answer 18

active against streptococci, but NOT staphylococci
NOT active against gm - (Cell wall blocks)
active against most gm + and gm - anaerobes

Question 19

aminoglycosides

Answer 19

active against staphylococci but NOT streptococci
active against respiratory and enteric gm -
NO activity against anaerobes

Question 20

macrolides

Answer 20

active against gm + aerobes
active against respiratory gm - but NOT enteric
active against most gm + anaerobes

Question 21

facultative anaerobes

Answer 21

are aerobes
can grow in anaerobic conditions
culture as aerobes
test susceptibility in aerobic conditions
in vitro susceptibility may not equal in vivo susceptibility

Question 22

additive/indifferent

Answer 22

2+2=4
used to extend spectrum
does not enhance activity of either

Question 23

synergism

Answer 23

what we hope for
combination enhances activity
static alone, cidial together
2+2=6

Question 24

antagonism

Answer 24

what we worry about
2-+2=2
activity of the combination is less than sum

Question 25

first questions for antibacterial use

Answer 25

is an antibacterial necessary

Question 26

use an antimicrobial when

Answer 26

bacterial infection systemic

Question 27

do not use an antimicrobial when

Answer 27

viral infection fungal infection parasitic infection

Question 28

maybe use an antimicrobial when

Answer 28

protozoal infection bacterial infection-local

Question 29

intravenous judicious use

Answer 29

highest concentrations highest risk of adverse effects severe systemic illness owner comfort level/animal temperament

Question 30

IM/SC judicious use

Answer 30

bioavailability is often complete risk of drug toxicity less than IV injection site reactions owner comfort level/animal temperatment

Question 31

oral judicious use

Answer 31

ileus-gi too slow colitis-gi too fast malabsorption drug interaction

Question 32

transdermal judicious use

Answer 32

not recommended no no no

Question 33

others routes of administration for judicious use

Answer 33

topical-eye,skin, wound inhaled intraarticular/regional limb perfusion

Question 34

site of infection

Answer 34

for most pathogens, the site of infection is the interstitial fluid protein binding is a major determinant of drug distribution of ISF low protein bound drugs have good destruction highly protein bound drugs have limited distribution>80%

Question 35

site of infection-exception to the rule

Answer 35

CNS, eye, prostate, bronchus, testes protective barriers that consist of tight junction between the endothelial limited drug movement into these areas lipids solubility or active transport

Question 36

site of infection-intracellular infection

Answer 36

lipophilic drugs have better penetration into cell than do hydrophilic drugs

Question 37

site of infection-abscesses and granulomas

Answer 37

drug diffusion slow lower cmax slower equilibrium lower blood supply to the area treatment unsuccessful without draining if you can drain and lavage the abcsess, antibacterial may not be necessary if can not drain-choose a more lipophilic drug. treat for al long time

Question 38

local tissue factors

Answer 38

affect the efficacy of some drugs purulent debris acidic environment hemoglobin/hemorrhages anaerobic conditions/necrotic tissue-decreased blood supply

Question 39

choosing an antibiotic

Answer 39

empiric treatment know which bacteria are commonly involved in which infections choose a drug likely to treat that bacteria