In vitro activity of lactoferricin solution against Malassezia pachydermatis from otitis externa in dogs and cats

Abstract

Background -Malassezia pachydermatis is a commensal organism of the skin, yet it may induce dermatitis and/or otitis. Lactoferricin (Lfcin) is an antimicrobial peptide obtained by the pepsin-mediated digestion of lactoferrin, a multifunctional innate-defence milk protein. The antibacterial activity of Lfcin is thought to cause alteration of bacterial membrane permeability, thus inducing cell death.Objectives -The aim of this study was to evaluate in vitro antifungal activity of different dilutions of Lfcin solution against M. pachydermatis strains isolated from ears of dogs and cats with otitis externa.Methods and materials -Fifty clinical Malassezia isolates from 40 dogs and 10 cats were tested. A dilution method in microtitre plates was used starting with a 20% Lfcin water solution. The different dilutions were 2:1 (13.3%), 1:1 (10%), 1:2 (6.7%), 1:5 (3.3%) and 1:10 (1.8%). Results were expressed as the value at which the growth of 50% (minimal fungicidal concentration MFC 50 ) and 90% (MFC 90 ) of yeast cells was inhibited.Results -All strains showed susceptibility to 20% Lfcin solution (100%). With 1:5 and 1:10 dilutions corresponding to 3.3% and 1.8% Lfcin solutions, all strains showed resistance. The MFC 50 and MFC 90 values were observed at 13.3% and 20% Lfcin solutions.Conclusions and clinical relevance -The results indicated that Lfcin solution exhibits the antimicrobial activity specific to antimicrobial peptides. In particular, the 20% solution can be effective in killing M. pachydermatis isolated strains. Some susceptibilities also are evident at lower concentrations of ≤6.7% for four strains.

Alternative approaches for treating canine otitis externa caused by Malassezia pachydermatis

“…For instance, Cafarchia et al (2014) found that a synthetic peptide showed antifungal activity in dogs with otitis, reducing clinical signs and yeast counts in cytological evaluation. Another study found that a peptide derived from milk protein, lactoferricin, exhibited antifungal activity against M. pachydermatis in vitro (Corona et al, 2021). In addition, the natural monoterpenoid β-thujaplicin was found to have antimicrobial activity against M. pachydermatis in both in vitro and in vivo studies (Nakano et al, 2005(Nakano et al, , 2006.…”

“…Recent years have seen significant advancements in alternative treatments for otitis externa caused by M. pachydermatis in dogs (Bismarck et al, 2020;Cafarchia et al, 2014;Chan et al, 2018a;Cole et al, 2007;Corona et al, 2021;Di Cerbo et al, 2016;Ebani et al, 2020;Mason et al, 2013), to help veterinarians in their routine. The search strategy for this review revealed several articles, summarized in Table 1.…”

“…It can be used to treat various conditions, including canine otitis externa caused by M. pachydermatis. Depending on their properties, chemical compounds may serve as adjuvants, synergists, or antifungal substances (Cafarchia et al, 2014;Corona et al, 2021;Henselm et al, 2009;Lee et al, 2022;Nakano et al, 2005;Siemieniuk et al, 2018).…”

Managing recurrent otitis externa in dogs: what have we learned and what can we do better?

“…Other novel antimicrobial compounds include various essential plant oils and extracts [60][61][62][63][64][65] , manuka honey 43 , antimicrobial peptides 66,67 , lactoferricin 68 and trisEDTA/monensin 69 . Early studies show good in vitro efficacy, although this can be more varied in the presence of mature biofilms 60 .…”