Skin therapy 2

Question 1

What factors affect AB decision making?

Answer 1

• efficacy
• ROA/ temperament of animal
• side effects (often considered mild)
• duration
• cost
• licensing/cascade
• CIs
• owner compliance
• local resistance patterns

Question 2

What are the 2 methods of AB selection for skin?

Answer 2

1. ) EMPIRICAL: classical superficial pyoderma/ folliculitis probably S.pseudintermedius, wet lesions - gram negatives? local knowledge of sensitivity patterns
2. ) C+S testing

Question 3

Name 3 classical CS for superficial pyoderma

Answer 3

pustule, papule and epidermal collarette

Question 4

What bacteria does >90% cases of superficial pyoderma invovle?

Answer 4

Staphylococcus pseudintermedius

Question 5

Which ABs are S.pseudintermedius not resistant to?

Answer 5

cefalexin, co-amoxiclav, oxacillin, meticillin, 1% resistance to enrofloxacin and marbofloxacin (this is 1998 data, new data in progress)

Question 6

What are alternative to ABs in tx of superficial pyoderma?

Answer 6

• 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).

Question 7

Name classical CS associated with deep pyoderma?

Answer 7

Those associated with superficial pyoderma (papules, pustules and collarettes) AND ALSO haemorrhagic pus and draining tracts.

Question 8

Bacteria in deep pyoderma

Answer 8

only 60-80% contain S.pseudintermedius. always base tx on C+S

Question 9

What is an interim choice for deep pyoderma whilst waiting for results?

Answer 9

Depends on cytology:
Cocci: cefalexine
Rods: fluoroquinolones
DURATION: many weeks, and at least 2 weeks beyond clinical cure.

Question 10

Why might AM resistance occur?

Answer 10

CLINICAL:
- wrong dose
- compliance
- absorption
- underlying cause
- resistance developed during tx
BACTERIA:
- intrinsic resistance (natural trait)
- acquired resistance (mutations etc..)

Question 11

Define MRSP

Answer 11

= 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

Question 12

T/F: most pet isolates are identical to human hospital-lineages

Answer 12

True - animals act as a reservoir

Question 13

How many humans carry MRSA?

Answer 13

< 2% of total UK population but medical staff are 4-5% carriers

Question 14

T/F: MRSP has a good prognosis if treated with topical therapy

Answer 14

True

Question 15

Tx options for MRSP - 3

Answer 15

1. ) 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)
2. ) topical therapy alone
3. ) off licensed tx with exotic AB

Question 16

Name 3 topical AM agents with proven efficacy against staphylococci

Answer 16

1. ) FUSIDIC ACID (low MICs shown for animal MRSA and MRSP recently)
2. ) CHLORHEXIDINE
3. ) BENZOYL PEROXIDE

Question 17

Describe susceptibility and resistance in topical antimicrobial agents

Answer 17

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)

Question 18

List some ‘exotic’ antibacterial drugs that can be used to treat MRSP

Answer 18

• Apramycin
• Amikacin (nephrotoxic)
• Chloramphenicol
• Rifampicin
• NOT vancomycin (for human MRSA treatment)
• THESE AREN’T RECOMMENDED WITHOUT ASKING FOR ADVICE

Question 19

What is the main risk factor for MRSA in dogs and cats?

Answer 19

repeated courses of antimicrobial therapy (AVOID REPEATED EMPIRICAL use of antimicrobial drugs in small animal patients)

Question 20

What is Convenia?

Answer 20

• 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

Question 21

Contraindications - Convenia

Answer 21

• hypersensitivity to cephalosporins or penicillin
• small mammals including GPs, rabbits
• dogs and cats < 8 weeks old

Question 22

What should you also consider when treating MRSP?

Answer 22

Carriage (other areas of body - nares, oral cavity, anus, genitals, conjunctivae and ear canal)
- hand hygiene + compliance = essential

Question 23

How should a practice deal with an MRSP dog?

Answer 23

• last consult
• disinfect everything after
• ask owner/dog to wait outside
• same principle of hygiene as for ringworm animals
• etc.