Equine Antimicrobials Flashcards
How do Beta lactam antibiotics work?
Interfere w/cell wall -> lysis
Which class of antimicrobial should be used FIRST LINE in streptococcal infections of the horse?
Beta Lactams
Which gram staining bacteria are beta lactams effective against?
Gram +
Which antimicrobial class works synergistically with beta lactams?
Aminoglycosides
Where do beta lactams not work well?
Abscesses
Are beta lactams effective against aerobes or anaerobes?
Anaerobes
What is the mechanism of action of cephalosporins?
Interfere w/cell wall -> lysis BUT more resistant to bacterial defences than Beta Lactams
How do aminoglycosides work?
30s Ribosomal Subunit -> DNA misread
What are the 2 main indictions for aminoglycoside use?
Gram -ve
Pseudomonas
What is the major SE of aminoglycosides?
Nephrotoxicity
What is the MOA of chloramphenicol?
50s Ribosomal Subunit - inhibit protein synthesis
What must be noted when using chloramphenicol in horses and other large animals?
PROHIBITED in food production animals
With which antimicrobials can chloramphenicol NOT be prescribed?
Penicillin
Aminoglycosides
Fluoroquinolones
Macrolides
What is the MOA of potentiated sulphonamides?
Inhibit DNA synthesis via the folic acid pathway
Where are potentiated sulphonamides ineffective?
Pus/necrotic tissue
Anaerobes
When can potentiated sulphonamides cause fatal arrhythmias?
when given with Detomidine!!
What is the MOA of tetracyclines?
30s ribosomal subunit binding - inhibit protein synthesis
Are tetracyclines static or cidal?
Static
Are aminoglycosides static or cidal?
Cidal
Are fluoroquinolones static or cidal?
cidal
Is chloramphenicol static or cidal?
Static
Are macrolides static or cidal?
static
Apart from infections, when are tetracyclines used?
Chelate Ca at myotendinous jct in foals w/contracted tendons
Inhibit MMPs in keratomalacia
What is the spectrum of action for tetracyclines?
Broad!!
What is the MOA of fluoroquinolones?
inhibit DNA gyrase - bactericidal
What is the spectrum of action for fluoroquinolones?
BROAD
esp good against gram neg
What are fluoroquinolones ineffective against?
Anaerobes
What may be a side effect of administering fluoroquinolones in foals?
Cartilage esions
On which antimicrobials do fluoroquinolones have an antagonistic effect?
Chloramphenicol
Rifampin
What is the MOA of macrolides?
50s ribosomal subunit - inhibit protein synthesis.
What are macrolides used to treat? (EQ)
R. Equi in foals
Why aren’t macrolides used in adult horses?
Colitis risk
What is the MOA of rifampin?
Inhibit bacterial RNA polymerase
Apart from viruses and fungi, which 3 pathogens is rifampin effective against in horses?
Staph
R. Equi
Mycobacteria
What is the MOA of metronidazole?
Broken down into free radicals –> DNA damage
