Micro1- AMDUCA, Penicillin

• empirical therapy: drug chosen on basis of differential diagnoses or most likely etiologic agent
• targeted therapy: drug chosen on basis of laboratory ID of etiologic agent(s) +/- antimicrobial susceptibility testing of agent
• prophylaxis: drug selected to prevent infection
• metaphylaxis: sort of a combination of empirical therapy and prophylaxis ("control of a disease that si already present in a group")

• Animal Medicinal Drug Use Clarification Act of 1994
• provided a framework for extralabel drug use: VCPR, general conditions for ELDU, condition for ELDU in FAs, compounding, and prohibitions

• vet responsible for making medical judgments about animals and client agrees to follow instructions
• vet has sufficient knowledge of animal to make at least preliminary diagnosis (physically seeing the animal)
• vet is available for follow-up to deal with txt failure/ adverse reactions

• no animal drug or dose approved for the use in question
• EL human drugs are not okay in food animals if an approved drug exists
• record keeping
• labelling

• must be done from approved finished dosage form human or animal drugs only
• cannot compound from raw bulk chemicals

• chloramphenical
• clenbuterol
• DES (diethylstilbestrol)
• ipronidazole/ nitroimidazoles
• furazolidone/ nitrofurizone
• sulfonamide drugs in lactating dairy cows (except sulfadimethoxine)
• fluoroquinolones
• glycopeptides
• cephalosporins
• [some of these have approved uses in FAs, but you must stay on label]

ONLY IN COMPANION ANIMALS- financial reasons are acceptable to use human drugs extra label, even when there is a labelled veterinary drug

minimum inhibitory concentration- conc drug needs to reach in order to be effective against a given organism (unique to each organism)

• time dependent
• concentration dependent
• cidal or static

time conc >MIC

for time-dependent drugs- the longer the drug conc is greater than MIC over the 24 hour period, the more effective the drug is

• for conc-dependent drugs- time doesn't matter; it just matters how high the Cmax gets
• **optimal Cmax:MIC ratio is ≥ 8

• AUC=area under the curve= integration of conc over time; this is a combination of time and Cmax dictating efficacy
• **AUC24:MIC ≤ 125

• + Streptococcus equi ssp. zooepidemicus 
• - Actinobacillus
• + Rhodococcus equi (foals)
• - Pseudomonas aeruginosa
• - Coliforms

• [this is a beta- strep!]
• Benzo-penicillins: (members of this class include) procaine penicillin (IM), potassium penicillin G (IV), potassium penicillin V (PO-NOT IN HORSES)

gram +, aerobic, and anaerobic

oral penicillins cause serious/ fatal diarrhea in horses (and rabbits for that matter)

• bactericidal
• time-dependent PK-PD relationship

disruption of bacterial cell wall by effing up penicillin binding proteins (PBPs)- enzymes that keep the cell wall together--> leads to cell membrane extrusion and disruption

• extracellular fluid
• DOES NOT cross BBB

• Strep equi ssp zoo- commensal opportunist
• Strep equi ssp equi- strangles, extremely contagious infectious disease; colonized gutteral pouch
• Strep dysgalactiae ssp equisimilis- respiratory opportunist, way less common than strep zoo

anaerobic bacteria are often involved in addition to the usual suspects (Step equi ssp zoo, actinobacillus)-- often need thoracocentesis to Dx

• Ampicillin (IV)
• Amoxicillin (PO)

Gram +, aerobic, anaerobic, SOME gram -

• Procaine penicillin (IM)
• Potassium Pen G (IV)
• Potassium Pen V (PO)

• Pasteurella multocida
• Anaerobes
• Pseudomonas
• Streptococcus
• Corynebacterium
• occasional coliforms

• Amoxicillin
• 10-21 days

• cloxacillin- used for mastitis
• oxacillin- not used therapeutically, but used in the lab to check for methicillin-resistance

• start empirical lepto therapy with ampicillin
• send out for MAT serology +/- PCR

Why is ampicillin the drug of choice? no nephrotoxicity, reaches kidneys, IV administration good for vomiting patients, renal elimination provides high urine concs, high margin of safety