title: Study to assess in vitro antimicrobial activity of nine ear cleaners against 50 Malassezia pachydermatis isolates.
abstract: BACKGROUND
  Ear cleaning is an important part of the successful therapy of otitis externa.
  
  
  OBJECTIVE
  To evaluate the in vitro activity of nine commercially available ear cleaners (Cerumaural(®), CleanAural Dog(®), Epi-Otic(®), MalAcetic Aural(®), Otoclean(®), Otodine(®), Sancerum(®), Surosolve(®) and TrizUltra™ + Keto) against 50 Malassezia pachydermatis isolates from clinical cases of canine otitis externa. To the authors' knowledge, this is the first study to analyse the in vitro susceptibility of a large number of M. pachydermatis isolates to a variety of ear cleaner products.
  
  
  METHODS
  Forty-nine hospital population dogs diagnosed with otitis externa with Malassezia spp. present on cytological examination of ear swabs and culture.
  
  
  METHODS
  The antimicrobial activity of nine ear cleaners was tested against 50 M. pachydermatis isolates from 49 clinical cases of canine otitis externa using an in vitro agar diffusion test.
  
  
  RESULTS
  There were statistically significant differences in activity between ear cleaners, with five showing excellent in vitro anti-Malassezia activity (CleanAural Dog(®), Epi-Otic(®), MalAcetic Aural(®), Sancerum(®) and TrizUltra™ + Keto), two moderate activity (Otodine(®) and Surosolve(®)), one variable activity (Otoclean(®)) and one no activity (Cerumaural(®)). There was a significant overall difference in susceptibility between M. pachydermatis isolates tested (P < 0.001).
  
  
  CONCLUSIONS
  Ear cleaners with activity against Malassezia may help to reduce the unnecessary use of antibiotic-containing polypharmaceutical ear medications. This study shows that the use of a large number of isolates may provide a more accurate account of the in vitro activity of a product.
authors.affiliation: Rutland House Veterinary Hospital, Abbotsfield Road, St Helens, Merseyside, WA9 4HU, UK. carly.mason@rutlandhousevets.co.uk
authors.forename: Carly L
authors.initials: CL
authors.lastname: Mason
authors.forename: Stephen I
authors.initials: SI
authors.lastname: Steen
authors.forename: Susan
authors.initials: S
authors.lastname: Paterson
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Cripps
mesh_terms: D000287:Administration, Topical; D000818:Animals; D003902:Detergents / Q000008:administration & dosage / Q000494:pharmacology*; D004283:Dog Diseases / Q000382:microbiology*; D004285:Dogs; D008290:Malassezia / Q000145:classification* / Q000187:drug effects*; D010032:Otitis Externa / Q000382:microbiology / Q000662:veterinary*
chemical_list: D003902:Detergents