Rezistencija vrsta roda Aspergillus serije Versicolores na antimikotike

master's thesis

• Title (english): Resistance of species Aspergillus series Versicolores to antimycotics
• Author: Agneza Rukavina
• Mentor: Maja Šegvić Klarić (mentor)
• Committee member: Maja Šegvić Klarić (predsjednik povjerenstva)
• Committee member: Daniela Jakšić (član povjerenstva)
• Committee member: Dubravka Vitali Čepo (član povjerenstva)
• Granter: University of Zagreb; Faculty of Pharmacy and Biochemistry; (Department of microbiology); Zagreb
• Defense date and country: 2023-11-27, Croatia
• Scientific / art field, discipline and subdiscipline: BIOMEDICINE AND HEALTHCARE; Pharmacy; Pharmacy

Abstract

Vrste roda Aspergillus, koje se često pojavljuju kao uzročnici oportunističkih mikoza (npr. A. flavus i A.
fumigatus), pokazuju visoki stupanj rezistencije na antimikotike. S obzirom da su vrste serije Versicolores
dominantni aspergili unutarnjeg prostora, posebice u vlažnim uvjetima, postavlja se pitanje njihove uloge u
nastanku oportunističkih mikoza i osjetljivosti na antimikotike, o čemu ima vrlo malo podataka u znanstvenoj
literaturi. Stoga su ciljevi ovog rada bili: 1) oblikovati “in-house” ključ za determinaciju vrsta serije
Versicolores na temelju morfologije kolonija u različitim uvjetima što može olakšati identifikacijski postupak;
2) ispitati osjetljivost izolata iz unutarnjih prostora Hrvatske na antimikotike koji se primjenjuju u sistemskim
mikozama. U sklopu ispitivanja morfoloških karakteristika kolonije su uzgajane 7 dana u tami na 6 različitih
hranjivih podloga (CYA, CYA20, DG-18, DRBC, MEA i SGA) te je razvijen je morfološki ključ za
prepoznavanje vrsta iz serije Versicolores. Sve ispitane vrste aspergila iz serije Versicolores dobro podnose
smanjen aktivitet vode u podlozi. Potrebno je najmanje 7 dana rasta kolonija za morfološku karakterizaciju i
očitavanje vrste iz serije Versicolores. Podloge koje omogućuju najbolju diferencijaciju među vrstama te bi se
mogle koristiti u fenotipskoj identifikaciji su: CYA, CYA20 i DRBC. Ispitivanje osjetljivosti serije na
antimikotike provedeno je disk-difuzijskom metodom na prilagođenom Mueller-Hinton agaru s dodanom
glukozom i metilenskim modrilom. Dobiveni rezultati su u skladu s postojećim podatcima o rezistenciji vrsta iz
roda Aspergillus. Utvrđena je rezistencija svih vrsta na kaspofungin te su predloženi mogući mehanizmi
rezistencije. Prijavljena je gotovo poptuna rezistencija serije na amfotericin B, koja bi mogla biti regionalno
prisutna i potvrđena je intrinzična rezistencija na flukonazol. Osjetljivost na ostale triazolne antimikotike bila je
raznovrsna, a primijećen je trend pojave rezistencije na vorikonazol i itrakonazol. Najveću učinkovitost imao je
posakonazol sa osjetljivošću svih ispitanih izolata, zatim itrakonazol sa samo 5 rezistentnih izolata od 20
ispitanih, dok je najslabiju učinkovitost imao vorikonazol sa 12 rezistentnih izolata na 20 ispitanih.

Abstract (english)

Species of the genus Aspergillus, which often appear as causative agents of opportunistic mycoses (e.g., A.
flavus and A. fumigatus), show a high degree of resistance to antifungals. Given that species of the Versicolores
series are dominant indoor aspergilli, especially in humid conditions, the question of their role in the occurrence
of opportunistic mycoses and their sensitivity to antimycotics arises, about which there is very little information
in previous literature. Therefore, the goals of this research were: 1) to create an "in-house" key for the
determination of the species belonging to Versicolores series based on the morphology of the colonies in
different conditions, which can facilitate the identification process; 2) to test the susceptibility of the isolates
present in indoor environment in Croatia to antifungal drugs used in treating systemic mycoses. As a part of the
morphological characteristics examination, the colonies were grown for 7 days in the dark and on 6 different
media (CYA, CYA20, DG-18, DRBC, MEA and SGA). As a result, a morphological key was developed to
identify species from the Versicolores series. All tested types of aspergilli from the Versicolores series tolerate
reduced water activity in the substrate well. A minimum of 7 days of colony growth is required for
morphological characterization and identification of species from the Versicolores series. The best suited media
for differentiation between species and for potential use in phenotypic identification are CYA, CYA20 and
DRBC. Antifungal susceptibility test was performed by disc-diffusion method on modified Mueller-Hinton agar
with added glucose and methylene blue dye. The obtained results correspond with the existing data on the
resistance of species from the genus Aspergillus. Resistance of all species to caspofungin was determined and
possible mechanisms of resistance were proposed. Resistance to amphotericin B was present in almost all tested
species, which could be regionally present. Intrinsic resistance to fluconazole has been confirmed. Susceptibility
to other triazole antifungals varied and a trend of resistance to voriconazole and itraconazole was observed.
Posaconazole was the most effective with all tested isolates being susceptible, followed by itraconazole with
only 5 resistant isolates out of 20 tested. Least effective was voriconazole with 12 resistant isolates out of 20
subjects.

• Keywords: Aspergilus Versicolores; morfološki ključ; antimikotici; disk-difuzijska metoda
• Keywords (english): Aspergilus Versicolores; morphological key; antimycotics; disk-diffusion method
• Language: croatian
• URN:NBN: urn:nbn:hr:163:776821
• Study programme: Title: Pharmacy; Study programme type: university; Study level: integrated undergraduate and graduate; Academic / professional title: magistar/magistra farmacije (magistar/magistra farmacije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2024-01-25 14:00:36