Antimicrobial Selection and Antimicrobials Flashcards
(52 cards)
What do you need to know about an antibiotic for selection?
Drug Class, Method of Action, Spectrum of Activity, Static or Cidal and Unique
What are the classes of antibiotics?
B-lactam, Phenicols, Flurquinolone, Macrolides, Sulfas, Tetracyclines
What is a time dependent antibiotic?
Needs to be above MIC for more than 75% of the dosing interval
What is a concentration dependent antibiotic?
Dose not required to be levels above MIC for most of period, need certain concentration
What is the difference between a static and cidal drug?
Static - stops growth (Sulfa, tetracyclines, phenicols, macrolide)
Cidal - kills bacteria (Beta lactams and fluroquinolones)
How does route of administration effect a drug?
IM/SQ more steady
IV need many administrations (level varies)
What is the mechanism of action of Beta Lactams?
Cell Wall Inhibitors - cripple production of bacterial cell wall that protects the cell from external environment
What is an example of a bacteria you shouldn’t use a beta lactam on?
Mycoplasma (no cell wall)
What are the two big categories of beta lactams?
Penicillin and Cephalosporins
What is the spectrum on Penicillin’s?
Gram positive and some anaerobes
What are some indications for using penicillin?
Systemic metritis, foot rot, anaerobic infection, mastitis
What dose of penicillin should be given?
Procaine - 3.5cc/100lbs
Penicillin G - 5cc/100lbs
Always ELDU (1cc not effective)
What is the withdraw on penicillin?
Procaine and Penicillin G: Unknown in milk (must test for it) and 30 days slaughter
Ampicillin - 48 hour milk and 7 day meat (more commonly used in dairy)
*Most trucks tested for beta lactams (very sensitive)
What is important to remember about the use of cephalosporins?
Must be according to label (off label illegal) - unless minor species
What spectrum are cephalosporins?
Gram negative and some gram positive
What are some examples of cephalosporins?
Naxel, Excenel and Excede
What are indications for Naxel/Excenel and Excede?
Naxel and Excenel: BRDC, Metritis, Foot Rot, Calf Scours and Salmonella
Excede: Respiratory and Metritis
What are their claims to fame?
No milk withdrawl
What should you warn your client about when prescribing Excenel vs Excede?
Excede - 13 day meat withdrawl - also administer in ear
Excenel - 4 day meat withdraw
RESIDUE COMMON
What is the mechanism of action for phenicol drugs?
Protein Synthesis - Interfere with protein synthesis by binding to the machinery that builds proteins, amino acids
What spectrum of activity are the phenicol’s?
Gram -/+
What are some drugs that are phenicols?
Nuflor and Resflor
What are these drugs labeled for?
BRDC, Metaphylaxis, Brain Infection, Diphtheria, Foot Rot
Should you use nuflor in a lactating dairy cow?
NO
