pharmacology 1st quiz TS Flashcards
which antimicrobial drugs interfere with bacterial cell wall synthesis?
beta lactams
bacitracin
vancomycin
cycloserine
which antimicrobial drugs act on bacterial cell membrane?
polymyxin b
colistin
which antimicrobial drugs interfere protein synthesis at 30s subunit?
tetracyclines
aminoglycosides
which antimicrobial drugs act on 50s subunit?
chloramphenicol
macrolides
lincosamides
which antimicrobials interfere with nucleic acid synthesis?
fluoroquinones
rifampin
metronidazole
which antimicrobials interfere with folic acid synthesis?
sulfonamides
diaminopyrimidines
which antimicrobials are narrow spectrum?
beta lactams
aminoglycosides
polymyxin b and colistin
which antimicrobials are bacteriostatic?
sulfonamides
tetracyclines
chloramphenicol
macrolides and lincosamides
what are the 3 efficacy predictors of antimicrobials?
type 1 - conc dependent
type. 2 time dependent
type 3 time dependent with pae (persistant suppression of bacteria)
what combo of antimicrobials produces additive effect?
bacteriostatic
what combo of drugs produces synergistic effect?
bactericidal drugs
what combo of drugs produces antagonistic effect?
bactericidal with bacteriostatic
what is transduction (antibiotic resistance)?
bacteria virus transfers genes
how do bacteria get antibiotic resistant from uptake of genes in environment?
transformation
what ways can bacteria decrease accumulation of drugs inside them?
decrease permeability thru cell membrane of gram negatives
energy dependent active efflux of drug
what is the prerequisite of folic acid in bacteria?
PABA
what are the 5 enteric sulfonamides?
succinylsulfathiazole sulfasalazine sulfquinoxaline sulfaguanidine phthalylsulfathiazole
what does a triple sulfa bolus consist of?
sulfinilamide, sulfathiazole, sulfamethazine
which sulfonamide is hydrolzyed in the bowl?
phthalylsulfqthiazole
which sulfonamide is split into 2 parts in intestine and treats dog coilitis?
sulfasalazine
ehat are the 2 moa of sulfonamides?
structural analog of PABA, gets substituted
act as antimetabolites and interfere with rna and dna
which. 2 sulfonamides can be used topically?
silver sulfadiazine
mafenide
which sulfonamide should be used for opthalmic apps because of neutral ph?
sulfacetamide
how are sulfonamides metabolized?
acetylation in liver
what effect does alkaline urine have on the excretion of sulfonamides?
increases fraction of dose eliminated in urine
what are the 2 immunological based toxicities of sulfonamides?
kcs ( dry eye)
hepatic necrosis
what is the non immunological effects of sulfonamide toxicity on kidney?
crystalluria
hematuria
renal tubular blockage
because of dehydration, keep well hydrated and aciduria protects
does a combination of sulpha drugs increase or decrease their solubility?
increase ( law of independent solubility)
which sulpha drug causes hypoprothrombinemia in dogs and chickens?
sulfaquinoxaline
what sulfa drug can cause aplastic anemia?
trimethoprim sulfadiazine ( potentiated sulfa)
which species can have hypoglycemia from taking sulfa drugs?
ducks and dogs
which breed of dog can get polyarthritis and hepatitis from sulfa drugs?
doberman pinschers
what gland may sulfonamides interfere with but is reversible?
thyroid gland
What group is sulfonamides in efficacy predictors?
type 2 antimicrobials, therefore ideal dosing maximizes duration of exposure
What type of molecule are diaminopyramidines?
lipid soluble organic bases
Are diaminopyramidines bacteriocidal or bacteriostatic?
bacteriostatic
How do diaminopyramidines block bacterial folate synthesis?
reversibly binds and inhibits dihydrofolate reductase
Which diaminopyramidine inhibits folate synthesis in protozoa?
pyrimethamine
Which diaminopyramidine can be given orally to ruminants?
ormetoprim
What are the 3 different diaminopyramidines?
Pyrimethamine, trimethoprim, and ormetoprim
Are potentiated sulfonamides bacteriostatic or bacteriocidal?
bacteriocidal (each one alone is bacteriostatic)
How do beta lactam antibiotics exert bactericidal activity?
interfere with transpeptidase enzyme that is responsible for formation of cross links (penicillin binding proteins - PBP)
What type of bacterial cell wall can beta lactams NOT penetrate?
gram negative
What 2 beta lactam drugs are “natural penicillins”?
Penicillin G
Penicillin V
Which natural penicilllin can be given orally?
Penicillin V
What are the 2 log acting formulations of Penicillin G?
Benzathine
Procaine
What bacteria are resistant to natural penicillins?
Pseudomonas, enterobacteriaceae and penicillinase producing staph
What are the 3 groups of semi synthetic penicillins?
Penicillinase resistant penicillins Broad spectrum (aminopenicillins) extended spectrum (carboxypenicillins)
What 3 penicillinase-resistant penicillins have good oral absorption?
Cloxacillin
Oxacillin
Dicloxacillin
What are penicillinase-resistant penicillins used to treat mostly?
staph infections
-bovine staph mastitis
What penicillinase-resistant penicillin can be formulated as an opthalmic ointment and treat staph and bacillus infections?
cloxacillin
What are the two drugs in the broad spectrum penicillins?
Amoxicillin
ampicillin
What are some related esters of ampicillin? (prodrugs)
bacampicillin
hetacillin
pivampicillin
talampicillin
What 5 penicillins are in the extended spectrum group?
ticarcillin, carbenicillin, piperacillin, mezlocillin, azlocillin
Why can’t procaine penicillin G be administered IV?
affects cardiac conduction system
What can be used to competitively inhibit penicillin excretion?
another organic acid, such as probenecid
Which penicillin is not excreted in urine?
Nafcillin (bile)
What can sodium benzylpenicillin produce in dogs and cats?
ataxia and convulsions (inhibits GABA)
What drug can produce anaphylaxis and CNS disorders in small mammals and reptiles?
procaine
What can procaine and postassium penicillin salts administered IV as a rapid bolus induce?
acute cardiac toxicities
What salt form should you use when administering penicillins IV?
sodium salt
What are the 3 first generation cephalosporins that can be given orally?
cefadroxil
cephalexin
cephradine
What are the 3 first gen cephalosporins that can be given parenteral?
cefazolin
cephalothin
cephapirin
Which first gen cephalosporin has greatest gram negative activity?
cefazolin
What bacteria are 2nd gen cephalosporins better at killing than 1st gen?
gram negative because increased resistance to lactamases
also anaerobes
Which drug is a “new generation” of cephalosporins?
ceftiofur (broader gram + activity)
How does ceftiofur compare to other 3rd gen cephalosporins?
better at strept
less activity against pseudomonas
What cephalosporin is 4th gen?
cefepime
Which 2 cephalosporins have the best oral absorption?
cephalexin
cefaclor
What is the only 2nd gen cephalosporin that can penetrate cerebrospinal fluid?
cefuroxime
What 3rd generation cephalosprins can attain high concentration in cerebrospinal fluid when meninges are inflammed?
ceftriaxone
cefotaxime
ceftazidime
ceftizoxime
What 2 cephalosporins can decrease platelet aggregation?
cephalothin
cefinetazole
How does clavulanic acid and sulbactam potentiate penicillin?
competitive inhibitor of beta lactamases of bacteria
What are the two kinds of Cabapenems?
Imipenems
Meropenems
What must imipenems be administered with?
cilastatin (renal enzyme inhibitor)
What bacteria does imipenems have activity on?
broad spectrum
gram negative aerobic
anaerobic
What is the adverse effect of imipenems?
seizures
How is meropenems different from imipenems?
more soluble
decreased seizures
What can be used against gram negative bacteria or pseudomonas if patient is allergic to penicillin?
monobactams
How do antimicrobials that inhibit protein synthesis target bacterial ribosomes instead of the host?
affinity for 70s size (eukaryotes is 80s)
What 2 parts of protein synthesis can antibiotics interfere with?
initiation
elongation of polypeptide chain
What 2 groups of antibiotics act on the 30 S subunit to inhibit protein synthesis?
aminoglycosides
tetracyclines
What 3 groups of antibiotics act on 50S subunit to inhibit protein synthesis?
macrolides
lincosamides
chloramphenicol and derivatives
Are aminoglycosides bacteriostatic or bacteriocidal?
bactericidal
What are the 6 aminoglycoside drugs?
streptomycin neomycin kanamycin gentamicin amikacin tobramycin
Why is one single dose of aminoglycosides q24 the same as many small ones?
post antibiotic effect (PAE)
What kind of bacteria do aminoglycosides act on?
aerobic gram negative bacteria
What aminoglycoside has the broadest spectrum?
amikacin
Which bacteria has natural permeability barrier to aminoglycosides?
streptococci
How are aminoglycosides administered?
parentally (never orally)
Where do aminoglycoside drugs concentrate in the body?
perilymph of the inner ear and in the renal cortex (attracted to phospholipids)
Why shouldn’t aminoglycosides and diuretic agents be used concurrently?
dehydration –> nephrotoxicity
What can happen when aminoglycosides are in high plasma concentrations after bolus?
non depolarizing neuromuscular blockade
What are 3 ways bacteria can be resistant to aminoglycosides?
enzymatic inactivation
ribosomal alterations
reduced permeability to drug
What is the efficacy predictor of aminoglycosides?
Type 1 - concentration dependent killing kinetics
How can renal uptake of gentamicin be inhibited?
alkalinizing the urine with sodium bicarbonate
Which aminoglycoside is too toxic for systemic use and used in topical applications?
neomycin
Which aminoglycoside is effective against gram positive AND negative bacteria?
paromomycin
What aminoglycoside is effective against Pseudomonas in dogs and cats?
Tobramycin
What are the 3 natural tetracyclines?
chlortetracycline
tetracycline
oxytetracycline
What are the 2 semi-synthetic tetracyclines?
minocycline
doxycycline
Are tetracyclines bacteriostatic or bacteriocidal?
bacteriostatic
What do tetracyclines bind to?
30s ribosomal subunit
Which tetracycline is the treatment of choice for equine monocytic ehrlichiosis? (potomac horse fever)
oxytetracycline
What tetracycline is effective against penicillinase resistant strains of staph aureus?
minocycline
What microorganisms are resistant to tetracyclines?
Proteus vulgaris
Pseudomonas aeruginosa
Mycobacterium
some Mycoplasma
Which tetracycline is given IM?
oxytetracycline
Which tetracycline is more completely absorbed in GI tract?
doxycycline
What are the 2 most lipid soluble tetracyclines?
Minocycline and doxycycline
What two tetracyclines are metabolized in the body? How are they then removed?
mino (oxidation)
doxy (bile diffusion) - can be used in renal failure
Why should IV (oxy?)tetracycline be given slowly?
chelates calcium in blood
What can IV injections of doxy in horses do?
induces cardiac arrhythmia – sudden death
How does oral tetracycline alter microflora in horses?
proliferation of clostridium perfringens or salmonella –> colitis
What group of efficacy predictors does tetracycline belong to?
type 3 - time dependent killing and PAE
What is the mode of action for chloramphenicol?
binds to 50s subunit
What can happen in prolonged admin of chloramphenicol?
bone marrow suppression (esp in cats) mitochondrial ribosome similar to bacterial one
What other antibiotic can chloramphenicol compete with and should not be administered with?
macrolides (erythromycin)
Which 2 types of bacteria are resistant to chloramphenicol?
Pseudomonas aeruginosa
enterobacteriaceae (readily acquired)
Which chloramphenicol drug is only available orally?
chloramphenicol base
Which chloramphenicol is hydrolyzed in small intestine by esterases?
chloramphenicol palmitate
Which chloramphenicol can be given IV/IM?
chloramphenicol succinate
How is chloramphenicol metabolized and therefore which animal has a slower clearance time?
conjugated with glucoronic acid
cats
Can you use chloramphenicol in food-producing animals?
NO!
Which chloramphenicols do not induce bone marrow stem cell damage?
thiamphenicol
florfenicol
What type of animals are most sensitive to chloramphenicol toxicity?
young animals
cats
impaired liver fxn
What is the side effect in newborn humans that are treated with high doses of chloramphenicol?
Gray baby syndrome
Which bacterial enzyme inactivates chloramphenicol and is acquired by plasmids?
acetyltransferase (florfenicol resistant to it)
What semi-synthetic chloramphenicol derivative is more water soluble?
thiamphenicol
Which chloramphenicol derivative is more potent and can be used in food producing animals?
florfenicol
What efficacy predictor group is chloramphenicol?
type 2 - time dependent
What are the 6 macrolide antibiotics?
erythromycin tilmicosin tylosin tiamulin azithromycin clarithromycin
How do macrolides differ in their mode of action than chloramphenicols?
unable to cross mitochondrial membrane and do not effect bone marrow
Are macrolides bacteriostatic or bacteriocidal?
bacteriostatic at therapeutic levels
bacteriocial slowly against strep
How does pH effect the antimicrobial action of macrolides?
high pH - enhanced
low pH - suppressed
Which macrolide is used to treat pink eye?
tiamulin
What is the preferred route of admin of macrolides?
oral (injections painful)
Which macrolide is metabolized by the liver?
erythromycin
Which macrolide is fatal to horses?
tylosin
Which macrolide has a type 3 efficacy predictor?
azithromycin
What 2 drugs are lincosamides?
lincomycin
clindamycin
What bacteria are not effected by lincomycin?
gram negatives
Which lincosamide is more lipid soluble and can cross BBB?
clindamycin
How are lincosamides excreted?
bile
What animals should lincosamides not be used in?
chinchillas, guinea pigs, hamsters
horses, ponies
rabbits
What efficacy predictor group is lincosamides?
type 2
What 2 groups of antimicrobials inhibit DNA replication?
fluorquinolones
metronidazole
What antimicrobial drug inhibits RNA synthesis?
rifampin
What are the 3 first generation fluorquinolones?
naildixic acid
oxolinic acid
cinoxacin
What are the 4 third generation fluoroquinolones?
orbifloxacin
levofloxacin
sparfloxacin
grepafloxacin
What are the 7 2nd generation fluorquinolones?
ciprofloxacin enrofloxacin marbofloxacin danofloxacin difloxacin norfloxacin enoxacin
What bacterial enzyme is inhibited by fluoroquinolones?
DNA gyrase enzyme
Which fluoroquinolone may have activity on anaerobes?
difloxacin
What type of bacteria are more susceptible to fluoroquinolones in an alkaline environment?
Enterobacteriaceae and other gram negative aerobes
What three conditions is pradofloxacin effective for against anaerobes, gram positives and gram negatives?
pradofloxacin
What are the two “new” generation fluoroquinolones?
premafloxacin
pradofloxacin
What are the 2 factors that affect the action of fluoroquinolones?
Cations decrease activity
low pH decreases activity
Which fluoroquinolones can be given in water for poultry infections?
enrofloxacin
sarafloxacin
Which fluoroquinolone is not widely distributed in tissues?
first
Which 2 tissues do fluoroquinolones not achieve a high concentration?
Cns, eye
Which fluoroquinolone is well distributed in bone, prostate and skin and all horse tissues?
enrofloxacin
What tissue does enrofloxacin, marbofloxacin and orbifloxacin achieve good levels?
prostate
Which 2 fluoroquinolones are highly excreted in milk?
enrofloxacin
danofloxacin
Which fluoroquinolones have active metabolites?
Difloxacin
Enrofloxacin
Pefloxacin
Which fluoroquinolone exception is excreted through faeces instead of urine?
difloxacin
What are some of the side effects of fluoroquinolones?
Photosensitivity CNS effects Crystalluria GI effects Arthropathy/Joint Arthropathy Ocular toxicities
What fluoroquinolone causes abnormalities in horses tendon cultures?
enrofloxacin
Why does fluoroquinolones given IV rapidly cause CNS effects?
inhibition of GABA
dont give to seizure patients
What is the most important bacterial resistance mechanism for fluoroquinolones?
increased efflux (alterations in gyrase enzyme and decreased uptake also mechanisms)
What efficacy group is fluoroquinolones?
Type 1 - max concentration
What is the MOA for bacitracin?
inhibits peptidoglycan synthesis
What are the indications for bacitracin?
topical tx of superficial infections in skin, mucosal surfaces, ear and eye
What is the MOA for novobiocin?
inhibits cell wall synthesis, RNA, DNA, protein, respiration
Do bacteria acquire resistance against novobiocin?
Yes, very quickly
What spectrum of activity does thiostrepton have? how is it administered?
gram + and some -
topical therapy
Which nitrofuran drug can have a carcinogec effect when administered chronically?
Furazolidone
How are nitrofurans administered?
Topically/orally
need acid environment to go into cell membrane
What is the MOA for virginiamycin and is it bacteriostatic or bacteriocidal?
Bacteriocidal
inhibits protein synthesis at 23s ribosomal subunit
What is the clinical use of virginiamycin?
growth promotion in swine, turkeys and laying hens
What clinical uses is carbadox used for?
growth promotant in swine
tx swine dysentery, bacterial enteritis
What happens if there is a toxicity of carbadox?
hypoaldosteronism (>100 ppm)
What is the MOA for vancomycin? Bacteriocidal or static?
inhibits peptidoglycan synthesis
bactericidal
What should vancomycin be combined with to treat enterococcal infections?
aminoglycoside (amikacin/gentamicin)
What are the 2 adverse effects of vancomycin?
nephrotoxicity
histamine release –> IV
What group of antibiotics is vancomycin in that is banned from using in food animals?
glycopeptides
Is methenamine bacteriostatic or bacteriocidal
depends on pH of urine
What condition is methenamine used to treat?
UTI in small animals
What other antibiotic should not be administered with methenamine?
sulfonamides
What 2 antibiotics interfere with the cell membrane?
polymyxin B
colistin (polymyxin E)
Are polymyxins bacteriostatic or cidal?
bacteriocidal
Why are polymyxins used for “bowel sterilization” before sx?
not absorbed from GIT when given orally
What is polymyxin B effective against in gram negative bacteria infections?
endotoxins
How are most polymyxins given?
topical use
What can polymyxins be combined with to act synergistically against gram negative bacilli?
sulfonamides
What is the MOA for metronidazole?
disrupts DNA structure
bacteriocidal
What type of bacteria is metronidazole most effective against?
systemic and enteric obligate anaerobic bacterial infections
What part of metronidazole can have a carcinogenic effect in rats?
a minor metabolite that evolved from splitting the metronidazole ring
Can nitroimidazoles be used in food producing animals?
NO - may be carcinogenic
What efficacy predictor group is metronidazole?
type 1 - concentration dependent
How is rifampin metabolized?
de-acetylation –> active metabolite
induces Cytochrome p450
How is rifampin excreted?
bile
What are some of the adverse effects of rifampin?
anemia/thrombocytopenia
hepatitis in dogs
what are the 5 bacteiostatic type drug groups?
sulfonamides tetracyclines chloramphenicol macrolides lincosamides
Which antibiotic causes bowel sterilization?
Polymyxin
What is it called when 2 static antibiotics work together?
additive effect
What group of antibiotics is effected by cations and pH?
fluoroquinolones
What cephalosporin is the only 2nd gen that can go into CSF?
cefuroxime
What antibiotic treats swine dysentery but has hypoaldosteronism toxicity?
carbadox
What are the antibiotics that are type 1 efficacy? (3)
aminoglycosides
fluoroquinolones
metronidazole
What are the 5 bacteriostatic antibiotics?
sulfonamides
tetracyclines
chloramphenicol, macrolides, lincosamides (50S)
Which beta lactam has low immunogenic profile?
monobactam (aztreonam)
Which cephalosporins are excreted in bile?
ceftriaxone
cefoperazone
Which bacteria are resistant to fluoroquinolones?
anaerobes
What is the first choice antibiotic for C. jejuni?
Erythromycin
What is the first choice drug for mycoplasma sp?
tiamulin
What bacteria are susceptible to metronidazole?
obligate anaerobes (clostridium, fusobacterium) protozoa
Which antibiotics are carcinogenic?
Metronidazole
Nitrofuran
Which antibiotic has good effect on pseudomonas and proteus?
Polymyxin
Which drug group has arthropies and ocular toxicities?
fluoroquinolones
What bacteria are resistant to lincomycin?
gram negatives
What are the susceptible bacteria groups of each of the cephalosporin generations?
First - gram +
2nd - gram -
3rd - better gram -
Ceftiofur - more gram +
Which drug group chelates calcium in teeth and bone?
tetracyclines
What is the 4th generation cephalosporin?
cefepime
Which drug group causes fatal enterocolitis in hind gut fermenters?
lincosamides
What are the 4 antibiotic groups banned in food animals?
Metronidazole
Vancomycin
Nitrofurans (Furazolidone)
Chloramphenicol
Which antibiotics inhibit GABA?
Fluoroquinolones
Penicillin
What drug is combined with tetracycline for synergism against kennel cough?
novobiocin
Which antibiotics treat prostate infection?
Enrofloxacin
marbofloxacin
orbifloxacin
(fluoroquinolones)
Which macrolide causes cardio toxicity?
tilmicosin
How is bacterial resistance acquired against rifampin?
single step mutation –> happens quickly
use with other antimicrobials