title: In vitro and in vivo activity of a killer peptide against Malassezia pachydermatis causing otitis in dogs.
abstract: In order to overcome the limitations inherent in current pharmacological treatments for Malassezia pachydermatis, the cause of otitis externa in dogs, the efficacy of a killer decapeptide (KP) was evaluated in vitro and in vivo. Sixteen dogs with naturally occurring M. pachydermatis otitis externa were enrolled, and the in vitro fungicidal activity of KP was evaluated using yeasts recovered from these animals. The therapeutic activity was evaluated in four groups of four animals each. The dogs were topically treated with KP (150 μl, 2 mg/ml) three times per week (group A) or every day (group B), treated with a scramble peptide every day (group C), or left untreated (group D). Assessment of clinical signs (pruritus, erythema, and lichenification and/or hyperpigmentation), expressed as mean of the total clinical index score (mTCIS), the population size of M. pachydermatis at the cytological examination (mean number of yeast cells at 40× magnification [mYC]), and culture testing (mean number of log10 CFU/swab [mCFU]), were conducted daily from the first day of treatment (T0) until two consecutive negative cultures (mCFU ≤ 2). KP showed an in vitro fungicidal effect against M. pachydermatis isolates, with an MFC90 value of 1 μg/ml. The mTCIS, mYC and mCFU were negative only in animals in group B after T8. Daily administration of KP for 8 days was safe and effective in controlling both clinical signs and the population size of M. pachydermatis causing otitis externa, thus offering an alternative to the currently available therapeutic or prophylactic protocols for recurrent cases of Malassezia otitis in dogs.
authors.affiliation: Dipartimento di Medicina Veterinaria, Università degli Studi di Bari, Bari.
authors.forename: Claudia
authors.initials: C
authors.lastname: Cafarchia
authors.forename: Davide
authors.initials: D
authors.lastname: Immediato
authors.forename: Giancarlo Di
authors.initials: GD
authors.lastname: Paola
authors.forename: Walter
authors.initials: W
authors.lastname: Magliani
authors.forename: Tecla
authors.initials: T
authors.lastname: Ciociola
authors.forename: Stefania
authors.initials: S
authors.lastname: Conti
authors.forename: Domenico
authors.initials: D
authors.lastname: Otranto
authors.forename: Luciano
authors.initials: L
authors.lastname: Polonelli
mesh_terms: D000287:Administration, Topical; D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology* / Q000627:therapeutic use*; D023181:Antimicrobial Cationic Peptides / Q000009:adverse effects / Q000494:pharmacology* / Q000627:therapeutic use*; D015169:Colony Count, Microbial; D003881:Dermatomycoses / Q000382:microbiology / Q000662:veterinary*; D004285:Dogs; D064420:Drug-Related Side Effects and Adverse Reactions / Q000473:pathology; D005260:Female; D008290:Malassezia / Q000187:drug effects* / Q000302:isolation & purification; D008297:Male; D008826:Microbial Sensitivity Tests; D050296:Microbial Viability / Q000187:drug effects; D010031:Otitis / Q000382:microbiology / Q000662:veterinary*; D016896:Treatment Outcome
chemical_list: D000935:Antifungal Agents; D023181:Antimicrobial Cationic Peptides
keywords: Malassezia pachydermatis; dogs; killer peptide; otitis; therapy