Antimicrobial activity of harzianic acid againstStaphylococcus pseudintermedius

The emerging concern about the increase of antibiotic resistance has encouraged research efforts to develop effective alternatives to counteract bacterial infections. Herein, we studied a new perspective to therapeutic treatment againstStaphylococcus pseudintermedius, an opportunistic pathogen documented as the major cause of skin, ear, and post-operative bacterial infections in dogs and cats. Antimicrobial activity of secondary metabolites produced by selected microbial strains belonging toTrichoderma,Talaromyces,ClonostachysandConiothyriumfungal genera has been tested againstS. pseudintermedius. Several extracts, particularly those obtained fromTrichoderma harzianumE45 and ET45, showed a significant antimicrobial activity towardsS. pseudintermediusmethicillin-resistant (MRSP) and methicillin-susceptible (MSSP) strains. Bioassay-guided fractionation of E45 and ET45 extracts allowed to isolate harzianic acid as the major compound responsible for biological activities (e.g. antimicrobial, antibiofilm formation and biofilm disaggregation).

Automated summary

The study found that harzianic acid produced by Trichoderma E45 and ET45 has significant antimicrobial activity against Staphylococcus pseudintermedius, making it a potential alternative for both methicillin-resistant and methicillin-susceptible strains. Bioassay-guided fractionation led to the isolation of harzianic acid as the major compound responsible for biological activities.