Modulatory effect of carvacrol on M. furfur and M. sympodialis virulence factors

BELLUCCI N; VIGLIONE T; GIAMMARINO A; GIUSIANO G; ANGIOLELLA L

Roma

Congreso; Congresso Nazionale della nuova Società Italiana di Microbiologia Farmaceutica ETS ?SIMiF ETS?, 14° incontro della Microbiologia farmaceutica. Prevenzione e terapia delle malattie infettive in un'ottica One-Health; 2023

Sapienza Università di Roma - Società Italiana di Microbiologia Farmaceutica

Introduction: Malassezia, an abundant genus of the fungal skin microbiota, is also noted as anopportunistic fungus because of its association with various skin diseases. A total of 18 specieshave been recognized, 10 species were isolated mainly from human skin, whereas the othersare normally isolated from animal skin. Malassezia sympodialis and M. furfur, the most common species isolated worldwide from healthy skin, have also been associated with various human skin disorders. Although this genus is considered the etiological agent of pityriasis versicolor, relationships with certain dermatoses, such as seborrheic dermatitis/dandruff, atopic dermatitis, and psoriasis, among others, have been reported. Colonization is enhanced by the pathogen’s virulence factors, including adherence properties that favor colonization and proliferation followed by biofilm formation in central vascular catheters. Cellular surface hydrophobicity (CSH), studies in recent years have suggested that CSH is also expressed by Malassezia spp. and may play a role in its pathogenicity.2 The increase on antimicrobial resistance has encouraged research to discover medicinal possessions of plants and their extracts, which can help as herbal sources of antimicrobial agents for protection against an extensive variety of bacteria and fungi drug resistant.Carvacrol is a monoterpene phenol and a major component of EO extract from oregano andother plants belonging to the Labiatae family. This monoterpene is considered nontoxic for humans, and it has been studied for its extensive pharmacological properties.Objective: The aim of this study was to evaluate the toxicity and the effect of the monoterpenecarvacrol on the virulence factors of M. furfur and M. sympodialis such as CSH, adherence, andbiofilm formation, as a new target to overcome the problem of drug resistance.Methods: A total of 16 Malassezia spp. clinical isolates were used in this study, including 8isolates of M. furfur and 8 M. sympodialis. The antimicrobial activity, the toxicity in the larvaemodel and the ability of carvacrol to inhibit virulence factors such as hydrophobicity, adherence,and biofilm formation of M. sympodialis and M. furfur was evaluated.Results and conclusion: The antimicrobial activity of carvacrol was in a range between 0.097–0.78 mg/ml. In presence of carvacrol the adhesion on plastic surface of M. furfur decreaseswith respect to the control only in 4/8 isolates while all isolates of M. sympodialis was inhibitedand inhibition of CSH was observed in 75% of the isolates of each specie. The inhibition of biofilm formation was more evident also after 48h in M.sympodialis respect to M.furfur. Carvacrolwas no toxic in Galleria mellonella larve. In conclusion we have demonstrated that in presenceof carvacrol the adherence to the plastic surface and CSH are two important virulence factorsfor microorganisms to initiate infection and biofilm formation were inhibiting in M. furfur and M.sympodialis. Further studies will have to be carried out to understand how these substances act,but the inhibition of some virulence factors could represent a new target to overcome the problemof drug resistance.