Treatment of Bacterial Skin Diseases (Marsella) Flashcards
Choice of abx determined by…
- Susceptibility of the bacteria
- Concurrent disease
- Depth of infection
- Length of tx
- Breed
- Age
- Owner constraints (time, money, drug admin)
Abx spectrum choice
- Start w/ narrow spectrum
- Some abx develop resistance rapidly
- Never use big guns first for pyoderma
Abx & glucocorticoid use?
Don’t do it!
Abx therapy for mixed infections
- If possible, select abx effective against various organisms
- If not possible, select abx effective against staph
Reasons for treatment failure
- Failure to ID all underlying causes
- Wrong abx
- Inappropriate dose
- Inappropriate length
- Concurrent steroids
- foreign body reaction
1st line abx for pyoderma
- Erythromycin
- Lincomycin
- Clindamycin
- 1st generation cephalosporins
2nd line abx for pyoderma
- Potentiated sulfonamides
- 3rd generation cephalosporins
- Amoxicillin/clavulanic acid
3rd line abx for pyoderma
- Fluoroquinolones
- Chloramphenicol
- Rifampin
- Amikacin
Erythromicin mechanism of action
- Macrolide, inhibits ribosomal protein synthesis
- Bacteriostatic
- Time-dependent
Erythromycin spectrum
Narrow spectrum for staphylococcus
Adverse effects of erythromycin
- Inhibition of cytochrome P450 (drug interactions)
- GI
Lincomycin mechanism of action
- Macrolide-like
- Bacteriostatic
Disadvantage of lincomycin
Rapid resistance (cross-reactive w/ erythromycin)
Clindamycin mechanism of action
Related to lincomycin (marcrolide-like)
Clindamycin uses
- Superficial pyoderma
- Deep pyoderma (recurrent infections)
- Cases of S. schleiferi
Advantage of clindamycin
Well tolerated by most patients
Cephalosporin mechanism of action
- Inhibition of synthesis of bacterial cell wall
- bacteriocidal
First generation cephalosporin (cephalexin) uses
- 1st line
- broad spectrum, but primarily gram+
First generation cephalosportin (cephalexin) disadvantages/adverse effects
- Increasing reports of resistance
- Vomiting/diarrhea
- Immune-mediated hemolytic anemia
- Immune-mediated thrombocytopenia
- Urticaria
- Drug eruptions (EM, TEN, PF)
- (Rarely - neurotoxicity, neutropenia, interstitial nephritis)
Potentiated sulfonamides mechanism of action
Interfere w/ synthesis of folic acid
Potentiated sulfonimides adverse effects
- Sulfa groups are very allergenic and my trigger hypersensitivity reactions (types I, II, III)
- Anemia, leukopenia, thrombocytopenia
- Fever
- KCS (keratoconjunctivitis sicca)
- Hepatopathy
- Arthropathy (shifting leg lameness)
- Cutaneous eruptions
- Hypothyroidism
- Polymyositis
Potentiated sulfonamides contraindications
- Anti-acids interfere w/ absorption
- Do NOT use in dobermans and rotweillers
- Incr. risk of arthropathy
- possible defect of detox
Silver sulphadiazine
- Topical sulfonamide
- Broad spectrum
- Ideal for pseudomonas
Third generation cephalosporins
- Convenia, simplicef
- Gram negative
- Broader spectrum than 1st gen
- Use as 1st choice only if compliance issues are anticipated (injection that lasts several days rather than owners giving pill)
Beta-lactamase resistant penicillins
- Oxacillin, dicloxacillin, nafcillin
- Expensive
- Excellent for staph
- TID
Amoxicillin/Clavulanic acid
- Broad spectrum (primarily gram+)
- Bacteriocidal
- Rapid absorption
- GI adverse effects
Chloramphenicol mechanism of action
- Inhibiting ribosomal protein synthesis
- Metabolized by liver
- Bacteriostatic
- Broad spectrum
Chloramphenical adverse effects
- Depression of microsomal enzymes (inhibits metabolism of other drugs)
- Aplastic anemia in owners (wear gloves when handling)
- GI, anorexia
- Elevated liver enzymes
- Anemia
- Peripheral neuropathy (large breed dogs)
Fluoroquinolones mechanism of action
- Inhibiting DNA gyrase (DNA replication)
- Bacteriocidal
- Concentration dependent
- Great penetration in tissues
- Accumulate in neutrophils and macrophages
Fluoroquinolone uses
- Broad spectrum
- Effective against Staph and Pseudomonas
- Resistant cases (NOT 1st line)
Fluoroquinolone disadvantages/adverse effects
- Absorption inhibited by anti-acids
- GI
- Neurological
- Seizures
- Arthropathy (incr. risk when receiving cyclosporins)
- Blindness (cats, Baytril)
- Do NOT give in cats or growing dogs
Enrofloxacin (Baytril)
- Metabolized into ciprofloxacin
- Food admin incr. amount of cipro
Fluoroquinalones (examples)
- Enrofloxacin (Baytril)
- Marbofloxacin (Zeniquin)
- Orbifloxacin (Orbax)
- Moxifloxacin
- Pradofloxacin (veraflox)
Doxycycline
- Resistant cases
- Time dependent
- Anti-inflammatory
- Vomit/diarrhea, nausea, yellow staining of teeth
- Esophageal strictures in cats
Mupirocin
- Topical abx
- Good for Staph
- Minimal systemic absorption
Polymyxin B
- Topical abx
- Used for resistant Pseudomonas
- Binds to cell membrane (more permeable)
Long term abx therapy (good/bad?)
- Not recommended
- Avoid pulse therapy (administration of supra-pharmacologic doses of drugs in an intermittent manner to enhance the therapeutic effect and reduce the side effects)
