Skin therapy 2 Flashcards
What factors affect AB decision making?
- efficacy
- ROA/ temperament of animal
- side effects (often considered mild)
- duration
- cost
- licensing/cascade
- CIs
- owner compliance
- local resistance patterns
What are the 2 methods of AB selection for skin?
- ) EMPIRICAL: classical superficial pyoderma/ folliculitis probably S.pseudintermedius, wet lesions - gram negatives? local knowledge of sensitivity patterns
- ) C+S testing
Name 3 classical CS for superficial pyoderma
pustule, papule and epidermal collarette
What bacteria does >90% cases of superficial pyoderma invovle?
Staphylococcus pseudintermedius
Which ABs are S.pseudintermedius not resistant to?
cefalexin, co-amoxiclav, oxacillin, meticillin, 1% resistance to enrofloxacin and marbofloxacin (this is 1998 data, new data in progress)
What are alternative to ABs in tx of superficial pyoderma?
- CLINDAMYCIN (Antirobe), narrow-spectrum, <20% resistance in S.pseudintermedius, not for recurrent cases
- TOPICAL AB SHAMPOOS: in combination or alone (effective in 70% cases after 3 week tx for superficial pyoderma), proven efficacy (Chlorhexidine, benzoyl peroxide), owner compliance (twice weekly bathing with 10 minute contact time).
Name classical CS associated with deep pyoderma?
Those associated with superficial pyoderma (papules, pustules and collarettes) AND ALSO haemorrhagic pus and draining tracts.
Bacteria in deep pyoderma
only 60-80% contain S.pseudintermedius. always base tx on C+S
What is an interim choice for deep pyoderma whilst waiting for results?
Depends on cytology:
Cocci: cefalexine
Rods: fluoroquinolones
DURATION: many weeks, and at least 2 weeks beyond clinical cure.
Why might AM resistance occur?
CLINICAL: - wrong dose - compliance - absorption - underlying cause - resistance developed during tx BACTERIA: - intrinsic resistance (natural trait) - acquired resistance (mutations etc..)
Define MRSP
= Meticillin-resistant Staphylococcus pseudintermedius
- the veterinary form of human MRSA
- the gene encoding broad-spectrum beta-lactam AB resistance is mecA positive
- present in UK since 2009
- can infect dogs, cats, (donkeys and horses)
- superficial and deep pyoderma
- also septicaemia, UTI, pneumonia, wound infections
T/F: most pet isolates are identical to human hospital-lineages
True - animals act as a reservoir
How many humans carry MRSA?
< 2% of total UK population but medical staff are 4-5% carriers
T/F: MRSP has a good prognosis if treated with topical therapy
True
Tx options for MRSP - 3
- ) systemic therapy if in vitro susceptibility identified (rare for MRSP< for MRSA - most cat and dog isolates are susceptible to potentiated sulfonamides and TCs (50% also clindamycin)
- ) topical therapy alone
- ) off licensed tx with exotic AB
Name 3 topical AM agents with proven efficacy against staphylococci
- ) FUSIDIC ACID (low MICs shown for animal MRSA and MRSP recently)
- ) CHLORHEXIDINE
- ) BENZOYL PEROXIDE
Describe susceptibility and resistance in topical antimicrobial agents
MIC data is based on plasma concentrations (systemic tx) thus MICs can be overcome by topical application as concentrations at site of infection are likely to be higher than plasma levels (liver and other places of metabolism bypassed). thus there are some cases of resistance reported (MRSA decolonisation with fusidic acid in people)
List some ‘exotic’ antibacterial drugs that can be used to treat MRSP
- Apramycin
- Amikacin (nephrotoxic)
- Chloramphenicol
- Rifampicin
- NOT vancomycin (for human MRSA treatment)
- THESE AREN’T RECOMMENDED WITHOUT ASKING FOR ADVICE
What is the main risk factor for MRSA in dogs and cats?
repeated courses of antimicrobial therapy (AVOID REPEATED EMPIRICAL use of antimicrobial drugs in small animal patients)
What is Convenia?
- long-acting cephalosporin
- e.g. Cefovecin = lyophilised powder vial
- only use based on C+S
DOGS: skin and soft tissue infections including pyoderma, wounds, abscesses…
CATS: skin and soft tissue abscesses, wounds… - should be considered on a par with fluoroquinolones in terms of importance for human health
Contraindications - Convenia
- hypersensitivity to cephalosporins or penicillin
- small mammals including GPs, rabbits
- dogs and cats < 8 weeks old
What should you also consider when treating MRSP?
Carriage (other areas of body - nares, oral cavity, anus, genitals, conjunctivae and ear canal)
- hand hygiene + compliance = essential
How should a practice deal with an MRSP dog?
- last consult
- disinfect everything after
- ask owner/dog to wait outside
- same principle of hygiene as for ringworm animals
- etc.
