Introduction to Antimicrobials Flashcards
what are the four quadrants with antimicrobials?
gram positive anaerobes
gram positive aerobes
gram negative anaerobes
gram negative aerobes
what do narrow spectrum antimicrobials target?
gram positive or gram negative
what is the breakpoint MIC for susceptible?
<= 4 microgram/ml
lower MIC for a given drug is __________, do not compare MICs between drugs
better
what do bacteriostatic drugs do?
inhibit growth of bacteria
what do bactericidal drugs do?
kill bacteria
what does time vs concentration affect?
dosing regimen
what do you want the peak concentration to be for concentration-dependent dosing?
multiple of MIC: more successful with higher dose at each administration
what is the post antibiotic effect?
suppression of bacterial growth that persists after brief exposure of organisms to antimicrobials
what are some things to consider with adverse event profiles?
can limit use to only a few days
monitoring for many potential side effects can make even cheap drugs quite expensive
drug allergies
what does the Animal Medicinal Drug Clarification Act of 1994 allow?
extralabel drug use
what are some drugs that are prohibited from extralabel use in food animals?
antimicrobial stewardship restrictions
carcinogens
what is an antibiotic?
substance produced by microorganisms that acts against other microorganisms
what are antimicrobials?
all agents that act against all types of microorganisms: bacteria, viruses, fungi, protozoa
what are the modified four quadrants?
Staphylococcus
Streptococcus
gram negative
anaerobes
what is an example of acquired resistance?
plasmids/chromosomal mutations encoding efflux pumps, altered drug targets, inactivation of drug, or altered permeability
what are the ways to perform susceptibility testing?
kirby bauer disc diffusion
Etest
tube dilution
what is the minimum inhibitory concentration?
lowest concentration that inhibits growth
breakpoints are set for different body locations and are threshold concentrations that indicate _________________
susceptible
intermediate
resistant
what does MIC stand for?
minimum inhibitory concentration
are water soluble/polar antimicrobials often absorbed well from the site of administration?
no
when might you prefer bactericidal drugs?
immunocompromised/immunosuppressed
bacterial meningitis
can mix bactericidal and bacteriostatic
what does time-dependent dosing mean?
want to maintain as much time above bacterial MIC as possible during dosing interval
more frequent administration
what does concentration mean with dosing regimen?
want peak concentration to be a multiple of the MIC
higher dose with each administration
what are the proposed mechanisms of the post antibiotic effect?
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
what does it mean that all medically important antimicrobials are required to be prescribed under a veterinary field directive with veterinarian oversight?
use of medically important drugs for growth promotion and feed efficacy no longer allowed
only disease prevention, control, and treatment
