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What are 3 high value differentials for a chronic draining tract in a dog's leg (not responsive to antibiotics)?
- Mycobacterium
- Nocardia
- Actinomyces
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What drug is a glycopeptide?
Vancomycin
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What is the MOA of vancomycin?
- binds to D-ala-D-alanine, preventing transglycosylation--> transpeptidases cannot form cross bridges--> autolysins break existing cross bridges--> cell lysis
- [different from beta-lactams b/c binds to a substrate, rather than the PBP enzyme]
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What are clinical applications of Vancomycin?
- drug of last resort in human medicine
- only SERIOUS infections with no other therapeutic options (Staph, Enterococcus, C. diff)
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What is the spectrum of vancomycin?
gram positives
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How is vancomycin administered?
- IV- diluted in bag of fluids and given over an hour
- PO only for C. diff in humans
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What are pharmcodynamic properties of vancomycin?
- time- and concentration- dependent (ie. AUC)
- -cidal
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What are adverse reactions to vancomycin? (4)
- [seen in people]
- severe phlebitis
- ototoxic
- nephrotoxic
- anaphylaxis/ histamine reaction (red man syndrome)
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What are important resistance mechanisms to vancomycin?
- VanA, VanB, VanC- A and B associated with transposons that are inserted by plasmids or chromosomes
- horizontally transmissible among Staph and Enterococci
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Describe the use of Linezolid. (4)
- useful for MRSA in humans but there are antimicrobial stewardship issues
- orally administered
- gram neg
- very expensive ($115 per pill)
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What is the spectrum of bacitracin?
gram + only
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What are pharmodynamic properties of bacitracin?
-cidal
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What are toxicities associated with bacitracin?
highly nephrotoxic
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How is bacitracin administered?
topically only
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What is the MOA of bacitracin?
interferes with transport of peptide building blocks of cell wall
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What is the spectrum of polymyxin B?
gram neg only
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What are pharmacodynamic properties of polymyxin B?
-cidal
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What are toxicities associated with polymyxin B? (2)
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Describe clinical used of polymyxin B?
- low-dose systemic use for sepsis
- does not kill bacteria at low doses but binds LPS
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Describe the anti-endotoxin effects of polymyxin B.
- decreases fever, plasma TNF, tachycardia, and neutropenia
- don't give with azotemia or dehydration!
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What are bacterial differentials for bacteremia in a dog? (4)
- Strep canis (+)
- Staph (+)
- Enterics, esp E. coli (-)
- Enterococcus (+)
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What bacteria have reported resistance to Vancomycin?
Staph and Enterococcus
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