Ispitivanje osjetljivosti sojeva gljivice Malassezia pachydermatis na mikonazol metodom mikrodilucij

master's thesis

• Title (english): Testing the sensitivity of Malassezia pachydermatis strains to miconazole using the microdilution method
• Author: Nikola Mohorović
• Mentor: Suzana Hađina (mentor)
• Committee member: Josipa Habuš (predsjednik povjerenstva)
• Committee member: Suzana Hađina (član povjerenstva)
• Committee member: Vilim Starešina (član povjerenstva)
• Committee member: Matko Perharić (član povjerenstva)
• Granter: University of Zagreb; Faculty of Veterinary Medicine; Zagreb
• Defense date and country: 2023-10, Croatia
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Veterinary Medicine; Veterinary Public Health and Food Safety

Abstract

Vrsta Malassezia pachydermatis zoofilni je kvasac koji prelazi iz komenzala u patogen
prilikom pojave pogodnih uvjeta za njegovo prekomjerno umnažanje te u pasa i mačaka
najčešće uzrokuje upalu vanjskog zvukovoda ili upale kože. Topikalna primjena antimikotika
iz skupine azola poput mikonazola predstavlja uspješan način liječenja, no često dolazi do
recedivirajućih oblika infekcija i razvoja kroničnog tijeka bolesti sa sve većim postotkom
izdvajanja rezistentnih sojeva ove vrste. Cilj ovog istraživanja bio je utvrditi osjetljivost vrste
M. pachydermatis na antimikotik mikonazol metodom mikrodilucije u bujonu. U tu svrhu
ispitano je 40 sojeva izdvojenih iz pasa i mačaka prilagođavajući standardizirani postupak
mikrodilucije propisan dokumentom E.DEF 7.3.2 od strane Europskog odbora za istraživanje
antimikrobne osjetljivosti. S obzirom na lipofilne odlike roda Malassezia korišten je Sabouraud
bujon s dodatkom 1% polisorbata Tween 80. Konačna gustoća suspenzije inokuluma iznosila
je 0,5 do 2,5 x10⁵ kolonija u mililitru. Mikrotitracijske ploče inkubirane su tijekom 72 do 96
sati na 37°C, a očitavanje je provedeno spektrofotometrom. Raspon dobivenih vrijednosti
minimalne inhibitorne koncentracije (MIK) iznosio je od 0,5 do >32 mg/L. Antimikrobna
rezistencija utvrđena je u dva soja čiji rast nije inhibirala ni najveća testna koncentracija
antimikotika od 32 mg/L za ≥50%. Ovo istraživanje ukazuje na potrebu za razvojem
standardiziranog postupka mikrodilucije u bujonu za rod Malassezia i dodatnim istraživanjima
u cilju razjašnjenja ulogu rezistencije u ove vrste.

Abstract (english)

The species Malassezia pachydermatis is a zoophilic yeast that changes from a
commensal to a pathogen when conditions are favorable for its excessive reproduction, and in
dogs and cats it most often causes inflammation of the external auditory canal or inflammation
of the skin. Topical application of antimycotics from the azole group, such as miconazole, is a
successful method of treatment, but often recurring infection and the development of a chronic
course of the disease occur, with an increasing percentage of resistant strains of this yeast
species being isolated. The aim of this research was to determine the sensitivity of M.
pachydermatis species to the antifungal agent miconazole using the broth microdilution
method. For this purpose, 40 strains isolated from dogs and cats were tested by adapting the
standardized microdilution procedure described by document E.DEF 7.3.2 of the European
Committee for Antimicrobial Susceptibility Research. Considering the lipophilic characteristics
of the genus Malassezia, Sabouraud broth with the addition of 1% polysorbate Tween 80 was
used. The final density of the inoculum suspension was 0,5 to 2,5 x10⁵ colony forming units
per milliliter. The microtiter plates were incubated for 72-96 hours at 37°C, and the reading was
performed with a spectrophotometer. The range of minimal inhibitory concentration (MIC)
values obtained was from 0.5 to >32 mg/L. Antimicrobial resistance was determined in two
strains whose growth was not inhibited even by the highest antifungal test concentration of 32
mg/L by ≥50%. This research points to the need for the development of a standardized broth
microdilution procedure for the genus Malassezia and for additional research aimed at
clarifying the role of resistance in these species.

• Keywords: M. pachydermatis; mikrodilucija u bujonu; MIK
• Keywords (english): M. pachydermatis; broth microdilution; MIC
• Language: croatian
• URN:NBN: urn:nbn:hr:178:436710
• Study programme: Title: Veterinary Medicine; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: doktor/doktorica veterinarske medicine (doktor/doktorica veterinarske medicine)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2023-10-12 09:23:56