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Flashcards in Lecture: antibiotics Deck (35)
1

Choice of AB is determined by

  • susceptibility of bacteria
    • main target is staph
  • concurrent dz
  • depth of infection
  • length of tx
  • breed
  • age
  • owner constraints

2

General rules for antibiotic therapy

  1. Select AB with narrow spectrum
  2. Select AB with wider margin of safety
  3. Try to never combine AB with glucocorticoids

3

AB for pyo

First line

  1. Erythromycin
  2. Lincomycin
  3. Clindomycin
  4. First gen cephalosporines

4

AB for pyo

Second line

  1. potentiated sulfonamides
  2. third gen cephalosporins
  3. amoxicillin/clavulanic acid

5

AB for pyo

Third line (Big guns)

  1. Fluoroquinalones
  2. Chloramphenicol
  3. Rifampin
  4. Amikacin

6

Erythromicin

  1. Macrolide; inhibits ribosomal protein synthesis
  2. Bacteriostatic, Time-dependent (TID)
  3. Narrow spectrum for staph
  4. Vomiting almost a given
  5. Inhibits cytochrome P450
  6. absorption delayed by food administration (inactivated by gastric secretions)

7

Lincomycin

  1. Macrolide-like AB
  2. Bacteriostatic, admin BID
  3. better absorption/distribution, less vomiting than erythromycin
  4. rapid resistance

8

Clindamycin

  1. Related to lincomycin, BID
  2. Absorption not altered by food
  3. Good penetration in fibrotic tissues
  4. Skin infection dose 11 mg/kg
  5. high effectiveness treating methicillin resistent staph
  6. Well tolerated by most, used frequently for S. schleiferi
    • nosocomial infections in people and dogs

9

Cephalosporins

  • Broad spectrum bacteriacidal
    • inhibits synthesis of bacterial cell wall

10

Cephalexin

  1. First generation cephalosporin, broad spectrum but mostly Gram +
  2. Adverse affects
    • GI
    • Immune mediated disease

11

Details about second line choices

  1. Potentiated sulfonamides
  2. Third generation cephalosporins
    • broader spectrum good for mixed infections
  3. Amoxicillin/clavulanic acid
    • will not work for s. pseudointermedius

12

Can't use clavamox if an infection is ...

methicillin resistent

13

Potentiated sulfonamides

  1. Interfere with synthesis of folic acid
  2. Immunogenic - triggers hypersensitivity
    • type I: IgE mediated (swollen, red)
    • type II: cytotoxic (Immune mediated thrombocytopenia)
    • type III: immune complex deposition (lupus)
  3. Antacids interfere with absorption

14

Shifting leg lameness

can be adverse affect of sulfas

15

Potentiated sulfonamides

Adverse affects

  • Anemia, leukopenia, thrombocytopenia
  • KCS
  • shifting leg lameness (lupus-like joint symptoms)
  • hypothyroidism

16

Two drugs that will affect thyroid levels

  • Pred
  • Sulfas

17

Dogs that should not see sulfas

  • Black and tan dogs: arthropathy
    • Dobies
    • Rotties

18

Silver sulphadiazine

  • topical sulfonamide
  • broad spectrum
  • ideal for Pseudomonas
  • ears and skin

19

Cefovecin (Convenia)

Defpodoxime proxetil (Simplicef)

Third gen cephalosporins

  • broader spectrum, active against G-
  • activity against s. pseudointermedius same as first gen
  • potential selection for methicillin resistence
  • Use as a first choice if compliance might be a problem (injectible)

20

Beta-lactamase resistant penicillins

  • Oxacillin
  • Dicloxacillin
  • Nafcillin
  • Expensive
  • Excellent for staph
  • TID

21

Amoxicillin/Clavulanic acid

(Clavamox)

  • Broad spectrum: primarily Gram +
  • Bacteriocidal
  • Rapid absorption
  • GI side effects
  • Dose: 22 mg/kg BID
  • Expensive for big dogs

22

Chloramphenicol

  • Broad spectrum, inhibits ribosomal protein synthesis, bacteriostatic
  • Time-dependent 50 mg/kg TID
  • metabolized by the liver
  • Owners: aplastic anemia 
  • anemia in animals is reversal
  • peripheral neuropathy in large breed dogs

23

Fluoroquinalones (Baytril)

  • only use in resistant cases as last resort
  • Concentration dependant (use once daily high dose)
  • Absorption inhibited by antacids
  • Great for deep pyo
  • GI, Nuero signs
    • lowers threshold for seizures

24

Enrofloxacin (Baytril)

Fluoroquinalone

  • bioconverted to cirpofloxacin
  • Bioavailability: 40%
  • 20 mg/kg once a day
  • expensive

25

Marbofloxacin (Zeniquin)

Fluoroquinalone

  • Bioavailability: 94%
  • Dose: 2.75 - 5.5 mg/kg SID

26

Orbifloxacin (Orbax)

Fluoroquinalone

  • Bioavailability: 97%
  • Dose: 2.5 mg/kg SID

27

Moxifloxacin

  • human product
  • used in dogs at 8 mg/kg SID

28

Pradofloxacin (Veraflox)

  • 3rd gen enhanced spectrum vet fluoroquinalone
  • Europe: labeled for dogs; US: labeled for cats
  • b/c baytril can't be used for cats
  • extensive ocular safety testing

29

bioavailability of cipro versus enrofloxacin

enrofloxacin has a more consistent bioavailability

30

Doxycycline

  • Time dependent antibiotic: 5-10 mg/kg BID
  • used for resistent cases
  • very expensive, substituted with minocycline
  • anti-inflammatory properties
  • adverse affects
    • GI
    • yellow staining of teeth
    • esophageal strictures

31

Topical AB

Mupirocin

  • Excellent for staph infections
  • rare resistance
  • minimal systemic absorption

32

Topical AB

Polymixin B

  • Used for resistant Pseudomonas
  • binds to cell membrane and alters structure to make permeable => cell death

33

AB you SHOULD NOT USE

Save for people

  1. Vancomycin
  2. Linezolid
  3. Synercid

34

Long term AB therapy

  • Not recommended
  • Avoid pulse therapy
  • Consider all triggering factors before considering immune stimulation

35

Conclusion

  1. Skin infections are secondary
  2. Try your best to identify underlying cause to avoid repetitive AB course that encourages resistence
  3. narrow spectrum first
  4. culture unresponsive cases before switching