Lecture: antibiotics Flashcards
1
Q
Choice of AB is determined by
A
- susceptibility of bacteria
- main target is staph
- concurrent dz
- depth of infection
- length of tx
- breed
- age
- owner constraints
2
Q
General rules for antibiotic therapy
A
- Select AB with narrow spectrum
- Select AB with wider margin of safety
- Try to never combine AB with glucocorticoids
3
Q
AB for pyo
First line
A
- Erythromycin
- Lincomycin
- Clindomycin
- First gen cephalosporines
4
Q
AB for pyo
Second line
A
- potentiated sulfonamides
- third gen cephalosporins
- amoxicillin/clavulanic acid
5
Q
AB for pyo
Third line (Big guns)
A
- Fluoroquinalones
- Chloramphenicol
- Rifampin
- Amikacin
6
Q
Erythromicin
A
- Macrolide; inhibits ribosomal protein synthesis
- Bacteriostatic, Time-dependent (TID)
- Narrow spectrum for staph
- Vomiting almost a given
- Inhibits cytochrome P450
- absorption delayed by food administration (inactivated by gastric secretions)
7
Q
Lincomycin
A
- Macrolide-like AB
- Bacteriostatic, admin BID
- better absorption/distribution, less vomiting than erythromycin
- rapid resistance
8
Q
Clindamycin
A
- Related to lincomycin, BID
- Absorption not altered by food
- Good penetration in fibrotic tissues
- Skin infection dose 11 mg/kg
- high effectiveness treating methicillin resistent staph
- Well tolerated by most, used frequently for S. schleiferi
- nosocomial infections in people and dogs
9
Q
Cephalosporins
A
- Broad spectrum bacteriacidal
- inhibits synthesis of bacterial cell wall
10
Q
Cephalexin
A
- First generation cephalosporin, broad spectrum but mostly Gram +
- Adverse affects
- GI
- Immune mediated disease
11
Q
Details about second line choices
A
- Potentiated sulfonamides
- Third generation cephalosporins
- broader spectrum good for mixed infections
- Amoxicillin/clavulanic acid
- will not work for s. pseudointermedius
12
Q
Can’t use clavamox if an infection is …
A
methicillin resistent
13
Q
Potentiated sulfonamides
A
- Interfere with synthesis of folic acid
- Immunogenic - triggers hypersensitivity
- type I: IgE mediated (swollen, red)
- type II: cytotoxic (Immune mediated thrombocytopenia)
- type III: immune complex deposition (lupus)
- Antacids interfere with absorption
14
Q
Shifting leg lameness
A
can be adverse affect of sulfas
15
Q
Potentiated sulfonamides
Adverse affects
A
- Anemia, leukopenia, thrombocytopenia
- KCS
- shifting leg lameness (lupus-like joint symptoms)
- hypothyroidism
16
Q
Two drugs that will affect thyroid levels
A
- Pred
- Sulfas
17
Q
Dogs that should not see sulfas
A
- Black and tan dogs: arthropathy
- Dobies
- Rotties
18
Q
Silver sulphadiazine
A
- topical sulfonamide
- broad spectrum
- ideal for Pseudomonas
- ears and skin
19
Q
Cefovecin (Convenia)
Defpodoxime proxetil (Simplicef)
Third gen cephalosporins
A
- 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
Q
Beta-lactamase resistant penicillins
A
- Oxacillin
- Dicloxacillin
- Nafcillin
- Expensive
- Excellent for staph
- TID
21
Q
Amoxicillin/Clavulanic acid
(Clavamox)
A
- Broad spectrum: primarily Gram +
- Bacteriocidal
- Rapid absorption
- GI side effects
- Dose: 22 mg/kg BID
- Expensive for big dogs
22
Q
Chloramphenicol
A
- 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
Q
Fluoroquinalones (Baytril)
A
- 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
Q
Enrofloxacin (Baytril)
Fluoroquinalone
A
- 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
