Kumar's Final Review - Anti-Microbials - AH Flashcards by Amy Herron

Name the 5 major categories of Antimicrobials based on MOA

Folic Acid synthesis inhibitors, 2. Beta-lactam antibiotics, 3. Protein Synthesis inhibitors (30s/50s) 4. Nucleic acid synthesis inhibitors, 5. Misc. (cell wall, nucleic acid synthesis 20s, cell membrane)

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Sulfonamides MOA?

PABA analoge: Inhibit folic acid synthesis by irreversibly blocking dihydroperoic acid

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Metabolism for Sulfonamides?

metabolized in liver (also in lungs). Acetylation = major pathway (poor in dogs)

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*What happens as a result of poor acetylation of sulfunamides in dogs?

*Urine precipitates = crystalluria (Tx by alkalizing the urine)

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Which class of sulfonamides exerts local action on the GIT?

Enteric sulfonamides (not absorbed in the GIT)

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What are some examples of enteric sulfonamides and what are they used for?

Sulfasalazine – colitis in dogs. Sulfaquinoxaline – coccidiosis in chickens. Sulfacetamide – eye (neutral pH)

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What are the topical sulfonamides?

Silver sulfadiazine and Mafenide

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Sulfonamide breed sensitivities ?

Dobermans → polyarthritis, fever, cutaneous eruptions, hepatitis. Duck&Dog → hypoglycemia (decreased thyroid hormone production)

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What are potentiated sulfonamides?

Combination of sulfonamide and diaminopyrimidine

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What is the spectrum for potentiated sulfonamides?

Broad spectrum, bacteriaCIDAL – synergisism between sulfonamides and diaminopyrimidine

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Prep of potentiated sulfonamides has what ratio?

Sulfamethoxazole + Trimethoprim (5:1)

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Side effect of potentiated sulfonamides in dogs?

Reversible hypothyroidism

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Sulfonamide Immunological SE?

Heptaic necrosis, Keratoconjumctivitis Sicca

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List 3 Diaminopyrimidines and how they are used

Primethamine – protozoa. Trimethoprim – used with sulfonamides (5 sulfa:1 trimeth). Ormethoprim – ruminants

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Major categories of Beta-lactam antibiotics?

Penicillin, Chephalosporin, Carbapenems, Monobactam

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Beta-lactam MOA?

Inhibits cell wall synthesis via penicillin binding protein interference – bactericidal action

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What are the natural Penicillins?

Penicillin V/G

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How is Penicillin V administered?

Oral (acid stable)

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Penicillin G drugs

Benzathine and Procaine

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How is procaine and procaine formulations administered?

Only by parenteral route, no IV (procaine → IM)

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What is the admin route that prolongs Benzathine action?

Reposatory prep. Lasts for 7days

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SE of Procaine?

Anaphylaxis and CNS in guinea pigs and chinchillas. Excitement in horses.

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List the Semi-Synthetic Penicillins with good oral absorption

Oxacillin Cloxacillin and DicIoxacillin (all are acid stable)

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List the semi-synthetic B-lactamase sensitive Penicillins

Amoxicillin and Ampicillin

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Which B-lactamase sensitive drug is more orally bio-available?

Amoxicillin

Which B-lactamase sensitive drug is a prodrug?

Ampicillin

Spectrum of action for extended spectrum penicillins?

Anti-pseudomonal

How are extended spectrum penicillins administered?

Parenterally w/ B-lactamase inhibitors

List 5 ext. spec. penicillins

Azlocillin, Carbenicillin, Mezlocillin, Ticarcillin, Piperacillin

List the beta-lactamase inhibitors

Clavulanic acid, Sulbactam

Beta-lactamase inhibitor MOA?

Competative inhibitor of B-lactamase binding sites.

Where do cephalosporins accumulate?

in the extracellular fluid

What 1st generation cephalosporin is administered via parenteral route to small animals?

Cefazolin

Which Cephalosporin has the broadest spectrum of action, is most potent and is stable against B-lactamase?

Cefeprim

Other B-lactams that are not susceptible to B-lactamase enzyme degredation?

Carbapenems and Monobactams

What is the spectrum of Carbapenems?

Broad

List the 2 Carbapenems

Imipenem and Meropenem

Give the Monobactama drug and when it is used?

Aztreonam – used in patients allergic to penicillin

2 drug groups that are 30s protein synthesis inhibitors

Aminoglycosides and Tetracyclines

Name 3 drug groups that are 50s protein synthesis inhibitors

Macrolides, Lincosamides, Chloramphenical

Which of the protein synthesis inhibitors is bacteriaCIDAL? What are the rest?

Aminoglycosides are -CIDAL, the rest are -STATIC

What is the spectrum of action for aminoglycosides?

Narrow spectrum – kills G-ve Aerobic bacteria

List 2 Aminoglycosides

Amikacin: Broadest spectrum. Paromomycin: G-ve and G+ve, protozoans

Why is a single does of Aminoglycoside drugs efficacious?

Has biphasic penetration via concentration dependent passive diffusion via porin channels. → post antibiotic effect

How are aminoglycocides administered?

Parenterally – 100% BA. Not given orally due to low BA

Where in the body do aminoglycosides tend to bind?

Inner ear and renal cortex

Vd of Aminoglycosides?

Extracellular. Vd is increased in lean/ cachectic animals

Aminoglycoside toxicity?

Nephrotoxic to cortex (excretion without metabolism) Ototoxicity – reversible. Neuromuscular Blockade

Which tetracycline is best absorbed in the GIT (orally)

Doxycycline

Are natural Tetracyclines metabolized?

List the natural Tetracyclines

Tetracycline, Chlortetracyclin, Oxytetracycline

How is Oxy administered?

Oral or parenteral

List the semi-Synthetic Tetracyclines

Minocycline, Doxycycline

How is minocycline metabolized?

Oxidation

Where is Doxy absorbed and why?

Lipid soluble (80-90% protein binding) → large intestine → is excreted in bile

What animal does Doxy kill?

Fatal in horses due to alterations to GIT flora

Adverse reactions of Chloramphenicol?

affects mammalian ribosome → reversible BM suppression, inhibition of mammalian mitochondrial synthesis.

What should you never give with Chloramphenicol?

Macrolides

Vd of Chloramphenicol?

Wide volume of distribution: eye, CNS, heart, lung, prostate, salivary glands, liver& spleen. Crosses the placental barrier and is in milk.

How is Chloramphenicol metabolized?

Glucoronidation – (cats = slow)

Why might you go to jail for administering chloramphenicol?

If you give it to food animals

While Chloramphenicol in food animals will land you in jail, what derivatives can be given to FA?

Thiamphenicol or Florfenicol

MOA of Florfenicol?

Inhibits peptidyl transferase enzyme

What is florfenicol more resistant to?

Bacterial resistance

Microlide Drugs (5)

Erythromycin, Tylosin, Tilmicosin, Tiamulin, Azithromycin

What is Erythromycin used to Tx?

Campylobacter jejuni in dogs

Which Macrolide Is fatal to horses but can be used to Tx mycoplasma?

Tylosin

What Macrolide treats respiratory infections due to high conc in lung tissues?

Tilmicosin

What is a SE of Tilmicosin?

Cardiotoxic if given via IV

Tiamulin is used to treat what?

Pinkeye, Mycoplasma

Which microlide has PAE?

Azithromycin

What do you not combine with Lincosamides?

Macrolides

MOA of Clindamycin?

Blocks translocation process of bacterial protein synthesis

What is Clindamycin used to Tx?

G-ve anaerobes and T. gondii

SE of lincomycin?

Enterocolitis in rabbits, horses and ruminats = fatal

MOA of Flouroquinolones?

DNA synthesis inhibition via Topoisomerase II

SE of flouroquinolones in the CNS?

Excitement (GABA) – don't give to animals with seziers

Flouroquinolones Adverse Effects

CNS excitement via GABA → don't give to animals with seizures. Arthropathy from chelation of MG. Retinal degeneration in cats. Accumulates in phagocytic cells.

Flouroquinolone drug?

Enrofloxacin → Tx pyoderma, ehrlichiosis

MOA of metronidazole?

DNA inhibition – is reduced by oxidoreductase enzyme in mitochondria → impairs bacterial DNA structure → cidal

Metronidazole metabolism?

Ocidoreductase enzyme

Metronidazole treats what microbes?

protozoans and anaerobes

MOA of rifampin?

Inhibits DNA dependent RNA synthesis

Why do you combine Rifampin with other drugs?

Susceptible to bacterial resistance. Add other drugs to avoid resistance

Which Antimicrobial drugs should not be used in Food producing animals?

Chloramphenicol –> aplastic anemia. Metronidazole → carcinogenic. Nitrofuran → furazolidone carcinogenic. Vancomycin

What antimicrobial is a growth promoter and prophylaxis in swine?

Carabadox (suppresses aldosterone production)

Drug used to Tx UTI in acidic urine?

Methnamine (do not give with sulfonamides)

Polymyxin B MOA?

Cationic, binds to phopholipids and disrupts cell membrane

What is given to sterilize the bowel before surgery?

Polymyxin B. Is also a topical

What antimicrobials are associated with aplastic anemia?

Sulfonamides and Chloramphenicols

Which antimicrobials reach the CNS/Brain

Chloramphenicol, Clindamycin, Metronidazole, Pot. Sulfonamides, Cephalosporin

Which antimicrobials are narrow spectrum?

Beta lactams, Aminoglycosides, polymyxins

Which antimicrobials are bacteriostatic?

Sulfonamides, Diaminopyrimidines, tetracyclines, Chloramphenicol, Macrolides and Lincosamides

Kumar's Final Review - Anti-Microbials - AH Flashcards

All the highlighted material from Kumar's review of Anti-microbials and nothing else.