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Antimicrobial Drug Characterisitcs Flashcards

1
Q

Beta lactams and aminoglycosides are incompatible ______

A

In vitro

- clinicians stagger animnoglycoside and penicillin dosings to avoid high in vivo concentrations

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2
Q

How do beta lactams inhibit cell wall synthesis?

A

Bind to penicillin binding proteins to prevent cross-linkage of peptidoglycan cell wall

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3
Q

How does the cidal action of beta lactams occur?

A

Osmotic imbalance between hypertonic bacterial cytoplasm and host isotonic environment

  • -> protoplasts bulge thru cell wall until cell bursts
  • -> if bacteria are in an environment isotonic to their cytoplasm, a static action occurs
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4
Q

________ decreases the activity of beta lactams

A

Purulent debris

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5
Q

What are the 3 mechanisms of beta lactam resistance?

A
  • degradation by bacterial enzymes
  • penicillin binding site alteration
  • reduced penetration (seen in gram neg structure = impaired crypticity)
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6
Q

What allows passage of resistance between species of bacteria and between genera?

A

Plasmids (between species) and transposons (between genera)

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7
Q

Crystalline penicillin G

A

IV, IM, SQ

  • rapid high concentrations
  • short duration of plasma concentrations
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8
Q

Procaine penicillin G

A

IM, SQ

  • flip flop kinetics
  • lower concentrations, but prolonged duration compared to crystalline pen-G
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9
Q

Benzathene penicillin G

A

IM

  • flip flop kinetics
  • extremely low concentrations with prolonged duration
  • little benefit in vet med
  • increases residue concerns in food animals
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10
Q

Penicillin G adverse reactions

A

Primary adverse reactions are allergic

  • due to degradation product penicilloic acid
  • some toxicity associated with salt (potassium pen G) or ester (procaine)
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11
Q

What animals should not be given beta lactams?

A

Guinea pigs, hamsters, rabbits

- due to hind gut floral disruption

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12
Q

Penicillinase resistant penicillins

A

Similar to pen G in structure, but not inactivated by penicillinase
- oxacillin or cefoxitin are standard for testing bacteria against drugs of this group due to their better storage stability and reliability

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13
Q

Which penicillinase-resistant penicillin is available for intramammary infusion in dairy cows?

A

Cloxacillin

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14
Q

Why do broad spec penicillins have better penetration of gram neg bacteria?

A

Increased crypticity

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15
Q

Which broad spec penicillin is used as an intramammary infusion?

A

Hetacillin

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16
Q

Which broad spec is absorbed twice as well orally in dogs and cats?

A

Amoxicillin over amipicillin

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17
Q

Qualitatively compare ampicillin sodium vs ampicillin trihydrate injections

A

Sodium ampicillin (veterinary) is injectable given by all parenteral routes

  • rapid absorption and elimination (every 8 hrs)
  • repository ampicillin trihydrate formulation may not be able to reach therapeutic concentrations unless organism is very susceptible (low concentration, prolonged duration)
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18
Q

Ampi and amoxicillin are not effective against ______, even at higher extra label doses

A

Enteric gram-negative bacteria

- especially true of trihydrate injectable suspensions

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19
Q

Adverse reactions of broad spec penicillins

A
  • large doses of ampicillin causes diarrhea in horses via entry into the bile (type B)
  • disrupts flora if given orally to ruminants (okay by injection)
  • trihydrate form too irritating for use in horses –> sterile abscesses
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20
Q

Extended spectrum penicillins are also called _________

A

Anti-pseudomonal

- increased crypticity, but able to bind to altered PBP

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21
Q

Potentiated penicillins

A

Have a penicillinase inhibitor added to the formulation to release penicillin

  • penicillinase inhibitor has no antibacterial properties
  • clavulanic acid and sulbactam
  • looses stability once hydrated, keep oral tabs in foil
  • only works in bacteria resistant via penicillinase
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22
Q

______ are susceptible to potentiated penicillin formulations

A

Bacteroides fragilis

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23
Q

1st generation cephalosporins

A

Similar to narrow-spec penicillins except:

  • not affected by penicillinase = good Staph activity, used in skin and bone infections!!!
  • not reliable against obligate anaerobic bacteria
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24
Q

How does cefazolin differ from other 1st generation cephalosporins?

A

Is the only injectable 1st gen!!

- better activity against E. coli than other 1st gens

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25
Q

Which 1st gen cephalosporins are approved for intramammary infusion for dairy cows?

A

Cephapirin

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26
Q

Which cephalosporins have 4 quadrant coverage?

A

Cefoxitin and cefotetan

- have good anaerobic activity, including B. fragilis

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27
Q

Which cpehalosporin family has a public health concern?

A

3rd generation

- resistance due to extended spectrum beta lactamases is of increasing public health concern

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28
Q

Which is the only cephalosporin effective against pseudomonas?

A

Ceftazidime

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29
Q

Which cephalosporin is the drug of choice in treating bacterial meningitis?

A

3rd generation cephalosporins

- ceftriaxone (expensive) or ceftazidime (more common)

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30
Q

Which cephalosporin family is not effective against carbapenem-resistant enterobacteriaceae?

A

4th gen, 5th gen, potentiated cephalosporins

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31
Q

Naxcel

A

Ceftiofur sodium

  • comes as a powder, requiring reconstitution
  • 4 day withdrawal for slaughter, no milk withdrawal!
  • cattle: BRDC, foot rot
  • swine, sheep: pneumonia
  • horses: respiratory infections
  • dogs: UTI
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32
Q

What is the only systemic antibiotic with no milk withdrawal?

A

Naxcel

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33
Q

Excenel

A

Ceftiofur HCL

  • shelf stable formulation
  • swine: respiratory disease, 4 day slaughter withdrawal
  • cattle: BRDC, foot rot, acute metritis
  • 2 day slaughter withdrawal, no milk withdrawal
  • -> exception: spectramast intramammary infusion does have a milk withdrawal of 72 hrs (lactating) or 30 day (dry)
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34
Q

Excede

A

Ceftiofur crystalline free acid (pure ceftiofur)

  • approved for cattle for 1 or 2 doses
  • approved in swine for respiratory disease (IM injection in the neck)
  • approved in horses for lower respiratory infections –> 2 IM injections 4 days apart
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35
Q

What is the drug of choice for skin and soft tissue infections due to staph, strep, e. coli, pasterurella, and proteus?

A

Cefpodoxime proxetil

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36
Q

What is the drug of choice for SSTI due to staph, strep, and pasturella and for UTI’s due to E. coli?

A

Cefovecin

  • injection once every 7-14 days for 2 injections
  • long half life due to protein binding
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37
Q

Monobactam spectrum is limited to

A

Aerobic gram-neg bacilli

- no activity against gram positives or obligate anaerobes

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38
Q

Which beta lactam has the broadest spectrum of activity of any antibiotic?

A

Carbapenems

- penetrates BBB and is enhanced in inflammation

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39
Q

High doses of imipenem can cause _______

A

Seizures

- nephrotoxicity is also seen due to reduction of active drug that reaches the urine, and the metabolite is nephrotoxic

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40
Q

Does meropenem cause nephrotoxicity or seizures?

A

No

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41
Q

Carbapenem-resistant enterobacteriaceae

A

Enterobacteriaceae resistant to all beta lactams including the carbapenems

  • reported in all 50 states (hospital and nursing homes)
  • resistant to all other antimicrobials used in medicine
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42
Q

CRE resistant mechanisms

A
  • carbapenemases
  • decreased crypticity
  • active efflux pump
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43
Q

Resistance to aminoglycosides

A

Due to plasmid-controlled aminoglycoside degradation enzymes in periplasmic space of gram neg bacteria
- also includes: decreased uptake into cell, modification of ribosome

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44
Q

Energy dependent phase 1 of aminoglycoside penetration

A

Oxygen dependent!

  • active uptake occurs at cytoplasmic membrane
  • process blocked by hyperosmolarity, low pH, and anaerobic conditions
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45
Q

Energy dependent phase 2 of aminoglycoside penetration

A

Disruption of cytoplasmic membrane, ion leakage is noted before cell death

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46
Q

Synergy between beta lactams and aminoglycosides

A

Beta lactams break bacterial cell wall, allowing greater entry of aminoglycoside

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47
Q

Neomycin is too toxic to use _______

A

Parenterally

  • used for enteric and topical infection
  • is extremely nephrotoxic!!
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48
Q

Gentamicin and amikacin are both veterinary approved for ______

A

Intra-uterine use in horses

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49
Q

Gentamicin

A

Want the trough to be < 2 mcg/ml

  • avoid glass containers
  • peak drawn at 1 hr, trough at 2 half lives (3-6 hrs)
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50
Q

Amikacin

A

Toxicity: want the trough to be <8 mcg/ml

- is less potent than gentimycin (is a more effective drug overall)

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51
Q

Nonantimicrobial use of gentamicin

A

Destroys ciliary body when injected into the eye, use to treat glucoma

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52
Q

What are the 3 adverse reactions of all aminoglycosides?

A
  • nephrotoxicity
  • ototoxicity
  • neuromuscular blockade
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53
Q

Toxcitiy of aminoglycosides is due to prolonged ________

A

High trough concentrations

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54
Q

What causes nephrotoxicity with aminoglycosides?

A

Binds covalently to intracellular organelles of proximal renal tubules

  • leads to cell damage/death
  • covalent binding is responsible for long residues in the kidney tissue
  • slaughter withdrawal for extralabel use in cattle at 18 months (is not illegal, but discouraged)
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55
Q

How to avoid aminoglycoside nephrotoxicity

A
  • use 24 hr dosing interval
  • keep patient well hydrated
  • limit other nephrotoxic drugs
  • TDM to optimize efficacy (peak) and minimize toxicity (trough) –> esp. in geriatrics!
  • IV calcium gluconate
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56
Q

How does amikacin differ from gentamicin relative to suscepibility and risk of nephrotoxicity?

A

Gentamicin
- gram neg % susceptibility in the low 90s
Amikacin
- gram neg % susceptibility in the high 90s
- less nephrotoxin than gentamicin

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57
Q

Ways to monitor aminoglycoside therapy to minimize the risk of nephrotoxicity

A

Increases in serum BUN or creatinine occur too late to be helpful

  • perform serial urinalyses and watch for: increasing tubular casts and protein, decreasing SG and increasing glucose
  • perform serial urine GGT: creatinine ratios (an increase in more than 3X baseline may indicate imminent toxicity)
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58
Q

Local environments decreasing aminoglycoside activity

A
  • acidic environments
  • low oxygen tension (required to have oxygen and active transport to get across cell membrane)
  • cellular debris
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59
Q

Macrolides have greater activity in an ________ environment

A

Alkaline

- also maintain activity in purulent debris!

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60
Q

Macrolide resistance

A

Either chromosomal or plasmid mediated

  • inactivates enzymes, changes in drug permeability, active drug efflux mechanisms
  • *cross resistance to other macrolides and lincosamides is common**
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61
Q

What is the drug of choice to treat chlamydia in cats?

A

Tetracycline

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62
Q

How do the newer macrolides differ in their activity versus older macrolides against gram-neg nonenteric pathogens?

A

Newer macrolides (ex; tilmicosin) have much greater activity against non-enterics

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63
Q

All medicated feeds with ________ are VFD

A

Macrolides

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64
Q

What antimicrobial has shown activity against chlamydia and is sometimes used in human medicine for this purpose?

A

Azithromycin alternative to doxycycline in human genital chlamydiosis

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65
Q

Macolides concentrate ______ due to their weak bases

A

Intracellularly

  • achieve high concentrations in macrophages, prostate, and milk
  • do NOT cross BBB
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66
Q

Macrolide - adverse reactions

A

Individual agent specific

  • injection site tissue rxn for vet formulations (esp older macrolides) resulting in sterile abscesses
  • hyperthermia due to anhydrosis may occur in foals receiving macrolides for R. pneumonia
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67
Q

Oral form of erythromycin is used in _______

A

Medicated feed for chickens (they have low stomach acid)

68
Q

Erythromycin is the drug of choice for ________

A

Campylobacter enteritis in man (azithromycin is better tolerated)

69
Q

Side effects of erythromycin

A

GI disturbances

  • causes intestinal spasms at antibiotic doses = diarrhea in adult horses and vomiting in dogs
  • erythromycin gluceptate and erythromycin lactobionate used at low doses as intestinal motility stimulant
70
Q

Main uses of erythromycin

A
  • feed additive in poultry to control mycoplasma respiratory disease
  • rare use of human injectable as prokinetic intestinal stimulant
71
Q

Tylosin is used predominantly in ______

A

Food animals as a feed additive

  • cattle: prevent liver abscesses
  • swine: mycoplasma pneumonia
  • poultry
72
Q

Non antibiotic use of tylosin

A

Treat large bowel diarrheas in dogs

  • unsure of mechanism
  • requires compounding tylosin
73
Q

What animals is tylosin NOT used in?

A

Horses

- causes colic and death!

74
Q

Tilmicosin is NOT used in _____

A

Ducks, goats, horses, pigs (injectable form), and man

CARDIOTOXIC

75
Q

What was the first repository BRDC treatment?

A

Tilmicosin

  • only used in cattle, rabbits, and sheep
  • still see tissue irritation, but not as severe
76
Q

What other medication is used to treat foal R. pneumonia?

A

Gamithromycin

  • not widely used
  • similar results to azithromycin+rifampin with 40% incidence of colic and lameness
77
Q

Tildipriosin ______ concentrations exceed _______ concentrations

A

Tissue; plasma

  • lung: 28 days
  • bronchial fluid: 21 days
78
Q

What medication is replacing erythromycin in foals and small animals due to fewer side effects and 24 hr dosing?

A

Azithromycin

- also used to treat bartonellosis in SA

79
Q

Atovaquone + azithromycin

A
  • used to treat cytauxzoonosis in cats (with early intervention!)
  • alternative to imidocarb in canine babesiosis
80
Q

Clarithromycin+rifampin is superior in treating ______

A

Foals with R. pneumonia

- protect foals from heat stress during and after treatement

81
Q

Lincosamides resistance

A
  • gram negs are resistant due to impermeable cell membranes and incompatible binding sites
  • chomosomal and plasmid-mediated
  • complete cross resistance between the lincosamides
  • cross resistance with macrolides and virginiamycin
82
Q

Which lincosamide is preferred in small animals?

A

Clindamycin

  • oral: vet med
  • injectable: human
83
Q

Which lincosamide is an intramammary product for dairy cattle?

A

Pirlimycin

84
Q

Clindamycin special spectra

A
  • treats Brachyspira hyodysenteriae in pigs

- used commonly in dermatology and dentistry for SA

85
Q

Oral clindamycin is not used in ______

A

Birds

- would require a 100 mg/kg po q6h dose (not practical)

86
Q

Clindamycin is effective in treating ________

A

Toxoplasmosis in cats

- crosses BBB with inflammation only in cats

87
Q

Clindamycin - adverse reactions

A
  • neuromuscular blockade
  • mostly GI symptoms with oral use in ruminants and suppresses hind gut flora in horses, rabbits, hamsters, guinea pigs (do NOT use!)
88
Q

Tetracycline - adverse reactions

A

Injectables are highly acidic! Cause tissue damage (esophageal ulcers in cats given oral doxy, injection site necrosis)

89
Q

Tetracycline - resistance mechanisms

A

Cross resistance within the group is common

  • plasmid mediated
  • reduced penetration of drug
  • active efflux
  • alterations to ribosome
  • enzymatic degradation of tetracycline
90
Q

Tetracycline non antibiotic effects

A
  • inhibit collagenase
  • may be anti-inflammatory or immunomodulating
  • oxytetracycline in single dose helps relax contracted tendons in foals and calves
91
Q

Which family has the broadest spectra, but also has a lot of resistance for common bacterial pathogens?

A

Tetracyclines

- applies to wild type bacteria, does not apply to high clinical efficacy

92
Q

What is the drug of choice for all rickettsia and lepto?

A

Doxycycline!

  • clears carrier state and causes remission for lepto
  • is also drug of choice for chlamydia in most species
93
Q

______ and ______ are more lipid soluble and cross BBB

A

Doxycycline and minocycline

94
Q

Chlortetracycline is used to treat _______

A

Anaplasmosis in cattle

  • causes remission, does NOT clear carrier state
  • only use as a feed additive
95
Q

What is the primary injectable tetracycline in vet med?

A

Oxytetracycline

- sustained release effect due to dose, not the vechicle (if given IV, the sustained effect goes away)

96
Q

Adverse effect of tetracyclines

A
  • potential teratogen in 1st trimester
  • staining of teeth from in utero exposure or exposure prior to eruption of adult teeth
  • hepatoxocitiy with use during pregnancy in the bitch
  • photosensitivity
  • GI floral disruption
  • nephrotoxic in high doses (especially expired tetras!!)
  • sudden collapse with rapid IV administration
  • tissue necrosis and pain at injection site
97
Q

What is the most common feed additive antibiotic?

A

Tetracycline

98
Q

Sulfonamides mechanism of action

A

Compete with para amino benzoic acid for incorporation into folic acid synthesis = inhibition of protein synthesis

  • mammalian cells use preformed folic acid and are not susceptible
  • purulent debris decreases activity due to high protein content and PABA content
99
Q

Folic acid pathway

A

PABA –> folic acid –> folinic acid –> purine and pyrimidines –> DNA

100
Q

Sulfonamide resistance development

A

Cross resistance between sulfonamides is complete!

  • chromosomal and plasmid mediated: altered cell permeability, refractive dihydropeteroate enzymes
  • chromosome also causes PABA hyperproduction
101
Q

Which sulfa requires a loading dose to be given?

A

Sulfadimethoxine (Albon)

- also give with long acting sulfas

102
Q

Common uses of sulfonamides

A
  • coccidiosis
  • nocardia
  • bovine foot rot: have an effect on aerobic organisms, so fusobacteria is altered, making them more susceptible
  • combos to enhance antibacterial or antiprotozoal activity
103
Q

Which antimicrobial is used orally in ruminants for systemic effects?

104
Q

What species is sulfas not used in?

A

Cats

- not tolerated well orally

105
Q

Which sulfa crosses the BBB?

A

Sulfadiazine

106
Q

Sulfa - toxicity

A

Nephrotoxicity due to crystal urea formation from acetylation (dogs don’t have this pathway)

107
Q

Sulfa type A adverse reactions

A

Crystalluria

  • problem with acidic urine and older sulfas (keep animals hydrated! Use triple sulfa to decrease risk while maintaining efficacy)
  • prone to drug interactions due to high protein binding
  • sulfaquinoxaline: hemorrhagic syndrome in chickens and dogs due to inhibition of intestinal vit K production
108
Q

Sulfa type B adverse reactions

A
  • keratoconjunctivitis sicca
  • polyarthropathy
  • hepatotoxicity
  • cutaneous drug eruptions
  • hypothyroidism
  • dobermans are most susceptible to type B!*
109
Q

Trimethoprim mechanism of action

A

Inhibition of DHFR, interfering with pruine and pyrimidine synthesis of the folic acid pathway (inserts between folic acid and folinic acid)

110
Q

Resistance develops quickly to just ______ as a single agent

A

Trimethoprim

- often used as a combo with sulfonamide to create a potentiated sulfa

111
Q

Selectivity for DHFR inhibition for trimethoprim and ormethoprim

A
  • bacterial
  • protozoal
  • mammalian
112
Q

Selectivity for DHFR inhibition fo rpyrimethamine

A
  • protozoal
  • mammalian
  • bacterial
113
Q

Potentiated sulfas - veterinary form

A

Trimethoprim + sulfadiazine

- TMS

114
Q

What renders TMS ineffective in an in vivo situation

A

Necrotic and tissue exudates for anaerobic infections

115
Q

Sulfadiazine is well absorbed orally in all species except _____

A

Cattle!

  • is destroyed by rumen or undergoes first bypass effect
  • may give to neonatal calves extralabelly
116
Q

Adverse reactions to sulfonamide content

A 
Type A
- crystalluria due to sulfonamide is not a concern (not enough sulfa in TMS)
Type B
- KCS
- polyarthropathy
- hepatotoxicity
- cutaenous drug eruptions
- hypothyroidism
117
Q

Adverse reactions to diaminopyrimide content

A

Type A

  • diaminopyrimidine inhibition on mammalian DHFR = bone marrow suppression and teratogenesis
  • -> supplementation of folinic acid serves as an antidote to the above toxicities
118
Q

What antimicrobial family is incrementally modified?

A

Phenicols

- chloramphenicol –> thiamphenicol –> florfenicol

119
Q

Phenicols resistance development

A

Plasmid mediated

120
Q

Chloramphenicol is effective against ______ infections

A

Enterococcal

  • previously drug of choice against Salmonella, resistance now runs at 50%
  • is an alternative to treat Rickettsia
121
Q

Chloramphenicol is banned in _____

A

Cattle

- destroyed by rumen

122
Q

Florfenicol is used in

A

Cattle

- repository (effect is not seen in dogs)

123
Q

Which species is born with near adult hepatic metabolism and how does this relate to chloramphenicol use?

A

Foals

  • glucuronyl transferase activity appears to reach adult levels in 1 week
  • would not use in any other neonate!!
124
Q

Which species has the longest chloramphenicol half life?

A

Cat (6 hours)

- horse as the shortest (1 hour)

125
Q

Chloramphenicol is not well tolerated in _____

A

Cats

  • leads to anorexia and depression
  • prone to drug interactions due to its inhibition of P450 system
  • is excreted into milk, so treating dam may affect neonate
126
Q

Florfenicol is contraindicated in ______

A

Horses

- causes severe diarrhea and colitis

127
Q

Long term use of ______ can cause bone marrow suppression in all species

A

Chloramphenicol

- reversible upon discontinuation of the drug

128
Q

In primates, chloramphenicol can lead to _______

A

Aplastic anemia

  • non dose dependent!
  • does not occur with florfenicol
  • survives cooking, so it is banned from all food animals!
129
Q

Mammalian cell topoisomerase 2 is not affected by ________ until drug concentrations are at least 100x higher than recommended concentrations

A

Fluoroquinolones

130
Q

Fluoroquinolones resistance development

A

Alteration of target, DNA gyrase, or topoisomerase 4

  • decreased entry into cell or increased active transport out of cell
  • chromosomally mediated!
  • cross resistance with other fluoroquinolones can occur
  • must have double mutation to be truly resistant
131
Q

What is the drug of choice for human septicemic salmonellosis?

A

Fluoroquinolones

- also used commonly in human campylobacter infections

132
Q

Enrofloxacin use in ruminants

A

Absorbed orally, though this use is banned

133
Q

Fluoroquinolones in horses

A

Vary in bioavailability

- ciprofloxacin is not absorbed

134
Q

Which antimicrobial is an enzyme inhibitor?

A

Fluoroquinolones

- causes adverse drug rxns, especially in conjuction with theophylline use

135
Q

Which antimicrobial is widely used in exotic animals and wildlife?

A

Enrofloxacin due to lack of anaerobic spectrum

136
Q

Identify order of susceptibility for each species to fluoroquinolone arthropathy

A

Horse > dog > cat and cattle

  • young animals are more susceptible
  • all horse formulations are extra label
  • is dose dependent and species dependent
  • do not use in large breed dogs up to 1 year and a half
137
Q

Fluoroquinolone adverse reactions

A
  • blindness due to retinal injury in cats

- pradofloxacin causes bone marrow suppression in dogs

138
Q

Fluoroquinolone public health concern

A

Monitored by National Antimicrobial Resistance Monitoring System due to resistance to campy and salmonella
- enrofloxacin for poultry was withdrawn in 2005

139
Q

Identify fluoroquinolone that have a higher probability to activity against pseudomonas

A

Ciprofloxacin and marbofloxacin

140
Q

Ionophore uses

A
  • anti coccidial for ruminants and poultry
  • improve feed efficiency, weight gain, or milk production
  • prevent fog fever in cattle
  • decrease ruminal bload
141
Q

Ionophores are very specific for ______

A

Gram positive bacteria and coccidia

- does not affect human health, causes drop in intracellular pH

142
Q

Rank major species regarding susceptibility to ionophore toxicity

A
  • cattle and poultry: relatively resistant
  • swine and small animals: intermediate
  • horses: most sensitive
143
Q

Ionophore toxicity

A

Severe muscle damage, myoglobinuria can cause renal damage

144
Q

Spectinomycin is an ________

A

Aminoicyclitol

- lacks toxicities seen with aminoglycosides (may cause neuromuscular blockade)

145
Q

_______ is limited to use in pigs only

A

Avilamycin

  • for reduction of incidence/severity of diarrhea with pathogenic e coli in weaned pigs
  • alters adhesive villi on gram negs so they cannot attach to enterocyte
146
Q

Bacteria in aerobic conditions are resistant to _______

A

Nitroimidazoles

  • do not possess reduction system
  • may function against facultative aerobic bacteria in anaerobic conditions
147
Q

Adverse reactions of metronidazole

A
  • neurologic with high doses in cats, dogs, horses
  • anorexia
  • bone marrow suppression
  • reddish brown urine
  • may interfere with olfaction in explosive detecting dogs
148
Q

Nitroimidazole public health concern

A

Carcinogenic effect in lab animals

- all nitroimidazoles are banned from use in food animals!

149
Q

What is the human anti-tuberculosis drug?

A

Rifampin

  • resistance develops rapidly during therapy (is never used as a single agent)
  • has been used to treat Johne’s disease but efficacy is not established
150
Q

Which drugs are used to treat Potomac horse fever?

A

Rifampin + erythromycin

  • as effective as oxytetracycline in resolution of clinical signs, but may not reduce fever as quickly
  • are available in oral forms
  • oral doxy is also an option
151
Q

Rifampin adverse reactions

A
  • dogs: elevated liver enzymes (rifampin induced hepatitis)
  • foals: self limiting diarrhea
  • humans: GI, flu like syndrome, blood dyscrasias, interstitial nephritis
  • discoloration of urine and tears (pink)
152
Q

Rifampin is an enzyme _______

A

Inducer!

- other drug will become subtherapeutic, need to adjust dose up based on TDM

153
Q

Isonizaid toxicity

A

CNS

- pyridoxine is antidote

154
Q

Nitrofuran adverse reaction and regulatory issues

A

Mutagenic and procarcinogenic = ban of extra label use in food animals (even topically)
- furazolidone is MAOI and must be used cautiously with drugs metabolized by this enzyme

155
Q

Novobiocin is approved for _______ with penicillin G for staphylococcal mastitis

A

Intramammary infusion

156
Q

Which miscellaneous antimicrobial is used to treat swine dysentery?

A

Tiamulin

- also associated with swine pneumonia due to Actinobacillus pleuropneumoniae

157
Q

Tiamulin is an enzyme _______

A

Inhibitor

- inhibits P450 and decreases metabolism of certain drugs (ionophores) where coadministration may lead to toxicity

158
Q

Which drug is used as a feed additive for the control of swine dysentery associated with S. hyodysenteriae and control of enteric salmonellosis?

159
Q

______, neomycin, and polymxin B make up the triple antibiotic topical ointment

A

Bacitracin

  • too toxic to give parenterally
  • orally is used to treat swine dysentery and C. difficile
160
Q

______ is used at extra low doses to bind to endotoxin

A

Polymyxin B

161
Q

Cats have high allergy to triple antibiotic due to ______

A

Bacitracin

162
Q

Silver sulfadiazine has antimicrobial activity due to the ______

A

Silver ion

- broad spec, including anti-pseudomonal activity

163
Q

Methenamine - effect of urine pH on activity

A

Requires urinary acidification to be converted into formaldehyde

  • urine pH of 5 in humans is preferred, 5.5 in animals
  • need to put on acidifying diet and add urinary acidifier (ammonium chloride)
164
Q

Methenamine - efficacy in treating a cystitis versus a pyelonephritis

A

Will not treat a pyelonephritis!

- passes thru kidney too rapidly for conversion to occur

165
Q

Which antibiotic is used for multi-drug resistant MRSA and vancomycin resistant E. faecalis and E. faecium?

A

Linezolid

- is an MAO inhibitor, use cautiously with other drugs impacting serotonin and catecholamines

Pharmacology 1 (15 decks)

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