Micro1- Cephs Pens Carbs

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  1. What are the major differentials for canine pyoderma? (3 major, 2 minor)
    • Staph pseudintermedius
    • Staph aureus
    • Staph schleiferi subsp Coagulans
    • Less common: Pseudomona aeruginosa, enteric bacteria in wounds
  2. What is empirical therapy for canine pyoderma? Why is this the empirical choice?
    • Cephalexin PO
    • activity against Staph, but no activity against Pseudomonas
    • inexpensive
    • high margin of safety
  3. Why can't you use amoxicillin or penicillin as empirical therapy for canine pyoderma?
    Most coagulase + Staph species produce penicillinase (type of beta-lactamase), which inactivates these antibiotics
  4. Coag + Staph MAY have acquired resistance to _______ by the following mechanism...
    • cephalexin; an acquired mecA gene encoding PBP2a
    • ex. MRSP (exclusive to dogs) and MRSA (mostly humans)- does not have inherent resistance to cephalexin, but may have acquired
  5. How are penicillins potentiated?
    • by combining with beta-lactamase inhibitors
    • competitively inhibit several bacterial beta-lactamases
  6. Describe the use of potentiated penicillins.
    beta-lactamase inhibitors are weakly antibacterial by themselves, but exhibit synergism when combined with a beta-lactam (ie. potentiated penicillins)
  7. What are potentiated penicillin products? What is there route of administration? (2)
    • Amoxicillin/ clavulanate- PO
    • Ampicillin/ sulbactam- IV
  8. What is the spectrum of potentiated penicillins?
    • Same spectrum as whatever penicillin the clavulanate/ sulbactam is combined with PLUS
    • more strains of E. coli, Klebsiella, non-MR Staph, Gram - anaerobes
  9. What are the anti-pseudomonal penicillins? How are they administered? (2)
    • Ticarcillin- Parenteral (adds coverage for Pseudomonas and even more enterobacteriacea)
    • Piperacillin- Parenteral (similar to ticar but $$$), not used much in vetmed
  10. What are the top differentials for a bacterial UTI in a dog? (4)
    • E. coli
    • enterics (Proteus, etc)
    • Enterococcus
    • Staphylococcus
  11. When should you treat a UTI empirically and not?
    Can treat empirically at first but should send culture on third occurence
  12. Describe the acquisition of urine for culture, and how this affects interpretation.
    • bladder is a sterile site, but urethral is not
    • More bacteria tolerated when free catch than with cysto
  13. Enterococcus has intrinsic resistance to __________.
    cephalosporins (and maybe others!)
  14. If you see ampicillin on a report, you can assume...
    amoxicillin has the same interpretation (ie. if susceptible to ampicillin, it's also susceptible to amoxicillin)
  15. What is the top bacterial differential for post-partum metritis in a cow?
    Arcanobacterium (Truperella) pyogenes- Gram + rods
  16. What is a good antimicrobial choice for metritis in a cow?
    • ceftiofur
    • CFA (crystalline free acid)- Excede
    • HCL- Excenel
    • no milk hold for either
  17. What are the third-generation cephalosporins and how is each administered? (6)
    • Cefotaxime- parenteral
    • Ceftriaxone- parenteral
    • Ceftazidime- parenteral
    • ceftiofur- parenteral, intramammary
    • cefovecin- parenteral (SUBQ!)
    • cefpodoxime- PO
  18. What is the only cephalosporin that has anti-pseudomonal activity?
  19. Describe the use of cefovecin.
    • [Convenia]
    • subq
    • long-acting (7-14 days)
    • labelled for skin infections in cats (inclu. P multocida abscess) and skin infections in dogs (including pyoderma, Staph pseud, Strep canis)
    • commonly used extralabel for UTI
  20. What is cefovecin commonly used for where it is NOT effective?
    URI- does not cover URI pathogens, poor resp tract penetration
  21. How many doses of cefovecin can you give?
    two at most; if the condition is not better after 4 weeks, you need to reevaluate your diagnosis
  22. What are adverse effects of cefovecin?
    • rare anaphylaxis
    • injection site edema/ seroma
    • mild elevations in ALT, GGT (dogs)
    • mild elevations in BUN (cats)
  23. What is the mechanism of action of carbapenems?
    disrupt bacterial cell wall by binding PBPs (penicillin binding proteins)
  24. What is the spectrum of carbapenems?
    • wide four quadrant coverage- gram + facultatives and anaerobes, gram - facultatives and anaerobes
    • good against Pseudomonas aeruginosa
    • Enterobacteriacae has resistance
    • considered a tertiary drug (big guns!)
  25. What is the route of administration of Imipenem, metabolism, and elimination?
    • IV only
    • rapidly metabolized by renal dihydropeptidase, so it is usually combined with cilastatin to inhibit dihydropeptidase and prolong activity
    • eliminated by kidneys
  26. What is the route of administration and elimination of Meropenem?
    • IV (ok to give SQ)
    • renal elimination
  27. Meropenem is slightly more potent against _________ than Imipenem.
    gram negs
  28. Describe NDM-1 beta lactamase.
    • gene carried on tranmissible plasmids that confers resistance to ALL beta-lactams, including carbapenems
    • shard among gram neg bacteria, including E. coli, Klebsiella, Acinetobacter, and Proteus
    • common in opportunistic infections in healthcare settings
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Micro1- Cephs Pens Carbs
2017-02-04 15:18:43
vetmed micro1

vetmed micro1
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