Antibiotics

Bacteriostatic vs. Bactericidal Antiobiotics

• Bacteriostatic
• Tetracyclines
• Sulfonamides
• Macrolides
• Lincosamides
• Chloramphenicol
• Bactericidal
• Aminoglycosides
• Penicillins
• Cephalosporins
• Fluoroquinolones
• Sulfas-Trimetoprim
• Metronidazole
• Nitrofurans

Cell Wall Synthesis Inhibitors (B-lactams)

• Penicillins
• Cephalosporins

Cell Wall Synthesis Inhibitors (B-lactams)

• Penicillins
• Work Best on Gram (+)
• Naturals: Pen G and V
• Animopenicillins: Amoxicillin, Ampicillin
• More GI side effects
• Potentiated with clavulanic acid (inactivates
• Beta-lactamases)
• Procaine Penicillin:
• Extended effect
• Long withdrawal period in food animals
• Cephalosporins
• Less union to plasmatic proteins than penicillins, therefore, they have less interference with other drugs.
• Cephalexin
• Ceftriaxone
• Ceftiofur
• Approved for food animals
• Withdrawal period of 3-5 days

Protein Synthesis Inhibitors

• Macrolides
• Lincosamides
• Chloramphenicol
• Aminoglycosides
• Tetracyclines

Protein Synthesis Inhibitors

• Aminoglycosides
• Best for Gram (-)
• Do not work on anaerobes
• Ototoxic and Nephrotoxic
• Amikacin
• Gentamycin
• Polimixin B
• Streptomycin
• Neomycin
• Tetracyclines
• Broad spectrum (Gram -, Gram +, mycoplasma)
• Tetracycline
• Oxytetracycline
• Doxycycline (This is the only one of the group that does not cause renal damage)
• Possible toxicities:
• Photosensitization
• Cardiac arrhythmias
• Teeth discoloration in young animals
• Renal damage
• GI

Protein Synthesis Inhibitors

• Macrolides
• Good for intracellular pathogens
• Colic in horses
• Erythromycin
• Tylosin
• Tilmicosin (highly toxic in swine and humans)
• Chloramphenicol
• Do not use in food animals because it is toxic to humans
• (bone marrow suppression)
• Good tissue distribution (including CNS)

DNA Synthesis Inhibitors

• Fluoroquinolones
• Sulfonamides (Sulfas/Trim)
• Metronidazole

DNA Synthesis Inhibitors

• Fluoroquinolones
• Good against Gram (-)
• Not good for anaerobes
• Are better absorbed in an acid environment, for this reason,
• anti-acids (e.g. ranitidine), decrease their absorption.
• Cause cartilage damage on young animals
• Enrofloxacin
• Sulfonamides
• Are better absorbed in an acid environment, for this reason,
• anti-acids (e.g. ranitidine), decrease their absorption
• Are bactericidal when combined with trimethoprim