Antimicrobial Review (need to know)

Question 1

what ADRs are seen with chloramphenicol

Answer 1

aplastic anemia in people, dose-dependent reversible anemia/neutropenia in cats with >60mg/kg/day, rare aplastic anemia/neutropenia in dogs

Question 2

what is the most severe ADR associated with clindamycin

Answer 2

fatal diarrhea in horses and rabbits! do not use in them

Question 3

what drug class is clindamycin in?

Answer 3

lincosamides

Question 4

what is the most severe ADR associated with erythromycin

Answer 4

fatal diarrhea in adult horses at antibiotic dose

Question 5

what are the 3rd generation cephalosporins

Answer 5

ceftiofur, cefpodoxime proxetil, cefovecin

Question 6

what are the 1st generation cephalosporins

Answer 6

cefazolin, cephalexin

Question 7

which drugs are hydrophilic and thus unable to penetrate abscesses, get into cells, or get into protected sites

Answer 7

aminoglycosides, beta-lactams (penicillins and cephalosporins)

Question 8

are beta-lactams time or concentration dependent? what does this mean for dosing?

Answer 8

time
need concentrations above MIC for 50% of dosing interval in immunocompetent patients with gram positive infections
80% for gram neg
90% for immunosuppressed

Question 9

are aminoglycosides time or concentration dependent? what does this mean for dosing?

Answer 9

concentration
Cmax must reach 8-10 times the MIC of the bacteria
increase the dose to get increased concentrations when treating intermediate susceptibility

Question 10

are fluoroquinolones time or concentration dependent? what does this mean for dosing?

Answer 10

concentration
AUC must reach 100-125 times the MIC of the bacteria for gram negs.
can increase dose and/or decrease interval b/c dose based on area under the curve (do not split dose!)

Question 11

what is the most important ADR with aminoglycosides and how can this be minimized

Answer 11

nephrotoxicity is associated with a trough concentration >2mcg/mL.
dose SID because a lower dose BID would allow more drug into the cells and increase risk for nephrotoxicity

Question 12

what dose of enrofloxacin is likely to cause ocular toxicity in cats

Answer 12

5mg/kg or higher

Question 13

which abx are cell wall synthesis inhibitors? are they static or cidal

Answer 13

beta-lactams
cidal

Question 14

are protein synthesis inhibitors static or cidal

Answer 14

most are static
aminoglycosides are cidal

Question 15

what is the MOA of fluoroquinolones

Answer 15

DNA gyrase inhibitors

Question 16

what is the MOA of nitroimidazoles

Answer 16

DNA synthesis inhibitors thru toxic metabolites

Question 17

what is the MOA of potentiated sulfonamides

Answer 17

folic acid inhibitors

Question 18

what is the MOA of beta lactams

Answer 18

cell wall inhibitors

Question 19

what is the MOA of aminoglycosides

Answer 19

protein synthesis inhibitors - 30s

Question 20

what is the MOA of tetracyclines

Answer 20

protein synthesis inhibitors - 30s

Question 21

what is the MOA of macrolides

Answer 21

protein synthesis inhibitors - 50s

Question 22

what is the MOA of lincosamides

Answer 22

protein synthesis inhibitors - 50s

Question 23

what is the MOA of phenicols

Answer 23

protein synthesis inhibitors - 50s

Question 24

what ADRs are seen with potentiated sulfonamides that limit their use

Answer 24

dobermans very predisposed to hypersensitivity reaction (hepatotox, thrombocytopenia). do not use in this breed
should also be avoided in hypothyroid animals

Question 25

what do you need to keep in mind with ear drops?

Answer 25

gentamycin is ototoxic and should not be used topically with ruptured ear drum risk of deafness and vestibular dz

Question 26

what is the spectrum of activity of tetracyclines

Answer 26

jack of all trades. master of rickettsia. lots of resistence out there

Question 27

what is the spectrum of activity of potentiated sulfonamides

Answer 27

jack of all trades. master of none. does not cover anaerobes

Question 28

what is the spectrum of activity of aminopenicillins? which drugs are in this group

Answer 28

strep!!, anaerobes!!, some gram neg aerobes (not a go to for gram negs unless in urine) amoxicillin and ampicillin

Question 29

what is the spectrum of activity of aminopenicillins with beta-lactamase inhibitors

Answer 29

same as aminopens alone (strep, anaerobes, some gram neg aerobes) PLUS a good choice for methicillin susceptible staphs and bacteroides

Question 30

what is the spectrum of activity of 1st gen cephalosporins? which drugs are in this group

Answer 30

strep!!, some meth susceptible staphs, ok for anaerobes, cefazolin ok for gram negs cefazolin and cephalexin

Question 31

what is the spectrum of activity of 3rd gen cephalosporins? which drugs are in this group

Answer 31

strep!!, some meth susceptible staphs, some anaerobes, gram negatives at higher doses ceftiofur best for gram negs ceftiofur, cefpodoxime proxetil, cefovecin

Question 32

what is the spectrum of activity of aminoglycosides

Answer 32

gram negatives!!, staphs (reserved for meth resistant ones) NO strep, NO anaerobes

Question 33

what is the spectrum of activity of fluoroquinolones

Answer 33

gram neg!!, staph (reserved for meth resistant ones), rickettsia, mycoplasma rarely strep, NO anaerobes active in purulent environments

Question 34

what is the spectrum of activity of macrolides and lincosamides? which drugs are in this group

Answer 34

gram positive aerobes some anaerobes -R. equi good for abscesses and intracellular macrolides - erthromycin, clarithromycin, azithromycin lincosamides - clindamycin

Question 35

what is the spectrum of activity of phenicols? which drugs are in this group

Answer 35

gram positive aerobes, anaerobes, some gram negs, mycoplasma, rickettsia good for abscesses and intracellular bacteria

Question 36

what is the spectrum of activity of nitroimidazoles

Answer 36

anaerobes!!! and protozoa

Question 37

how are beta lactams eliminated

Answer 37

in the urine at high concentrations, so great for UTI!!

Question 38

what is the general rule for remembering static vs cidal

Answer 38

protein synthesis inhibitors (except aminoglycosides) are static. everything else is cidal

Question 39

what is the general rule for remembering excretion

Answer 39

macrolides, lincosamides, nitroimidazoles and pradofloxacin mostly hepatic elimination

Question 40

what is the general rule for remembering distribution

Answer 40

beta-lactams and aminoglycosides are not widely distributed b/c they are water soluble

Question 41

what is the general rule for remembering oral absorption

Answer 41

benzylpenicillins and aminoglycosides are not orally absorbed in any species