Name the 5 major categories of Antimicrobials based on MOA
1. 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)
PABA analoge: Inhibit folic acid synthesis by irreversibly blocking dihydroperoic acid
Metabolism for Sulfonamides?
metabolized in liver (also in lungs). Acetylation = major pathway (poor in dogs)
*What happens as a result of poor acetylation of sulfunamides in dogs?
*Urine precipitates = crystalluria (Tx by alkalizing the urine)
Which class of sulfonamides exerts local action on the GIT?
Enteric sulfonamides (not absorbed in the GIT)
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)
What are the topical sulfonamides?
Silver sulfadiazine and Mafenide
Sulfonamide breed sensitivities ?
Dobermans → polyarthritis, fever, cutaneous eruptions, hepatitis. Duck&Dog → hypoglycemia (decreased thyroid hormone production)
What are potentiated sulfonamides?
Combination of sulfonamide and diaminopyrimidine
What is the spectrum for potentiated sulfonamides?
Broad spectrum, bacteriaCIDAL – synergisism between sulfonamides and diaminopyrimidine
Prep of potentiated sulfonamides has what ratio?
Sulfamethoxazole + Trimethoprim (5:1)
Side effect of potentiated sulfonamides in dogs?
Sulfonamide Immunological SE?
Heptaic necrosis, Keratoconjumctivitis Sicca
List 3 Diaminopyrimidines and how they are used
Primethamine – protozoa. Trimethoprim – used with sulfonamides (5 sulfa:1 trimeth). Ormethoprim – ruminants
Major categories of Beta-lactam antibiotics?
Penicillin, Chephalosporin, Carbapenems, Monobactam
Inhibits cell wall synthesis via penicillin binding protein interference – bactericidal action
What are the natural Penicillins?
How is Penicillin V administered?
Oral (acid stable)
Penicillin G drugs
Benzathine and Procaine
How is procaine and procaine formulations administered?
Only by parenteral route, no IV (procaine → IM)
What is the admin route that prolongs Benzathine action?
Reposatory prep. Lasts for 7days
SE of Procaine?
Anaphylaxis and CNS in guinea pigs and chinchillas. Excitement in horses.
List the Semi-Synthetic Penicillins with good oral absorption
Oxacillin Cloxacillin and DicIoxacillin (all are acid stable)
List the semi-synthetic B-lactamase sensitive Penicillins
Amoxicillin and Ampicillin
Which B-lactamase sensitive drug is more orally bio-available?
Which B-lactamase sensitive drug is a prodrug?
Spectrum of action for extended spectrum penicillins?
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?
Which Cephalosporin has the broadest spectrum of action, is most potent and is stable against B-lactamase?
Other B-lactams that are not susceptible to B-lactamase enzyme degredation?
Carbapenems and Monobactams
What is the spectrum of Carbapenems?
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
Nephrotoxic to cortex (excretion without metabolism) Ototoxicity – reversible. Neuromuscular Blockade
Which tetracycline is best absorbed in the GIT (orally)
Are natural Tetracyclines metabolized?
List the natural Tetracyclines
Tetracycline, Chlortetracyclin, Oxytetracycline
How is Oxy administered?
Oral or parenteral
List the semi-Synthetic Tetracyclines
How is minocycline metabolized?
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?
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?
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?
What Macrolide treats respiratory infections due to high conc in lung tissues?
What is a SE of Tilmicosin?
Cardiotoxic if given via IV
Tiamulin is used to treat what?
Which microlide has PAE?
What do you not combine with Lincosamides?
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.
Enrofloxacin → Tx pyoderma, ehrlichiosis
MOA of metronidazole?
DNA inhibition – is reduced by oxidoreductase enzyme in mitochondria → impairs bacterial DNA structure → cidal
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