MRSA: methicillin-resistant Staphylococcus aureus MRSE: methicillin-resistant Staphylococcus epidermidis PABA: para-aminobenzoic acid PRSP: penicillin-resistant Streptococcus pneumonia VREF: vancomycin-resistant Enterococcus faecium A Review on Antimicrobial Activity of Mushroom (Basidiomycetes) Extracts and Isolated Compounds

Despite the huge diversity of antibacterial compounds, bacterial resistance to first-choice antibiotics has been drastically increasing. Moreover, the association between multiresistant microorganisms and nosocomial infections highlight the problem, and the urgent need for solutions. Natural resources have been exploited in the last years and among them, mushrooms could be an alternative source of new antimicrobials. In this review, we present an overviewof the antimicrobial properties of mushroom extracts and highlight some of the active compounds identified, including lowand high-molecular weight (LMW and HMW, respectively) compounds. LMW compounds are mainly secondary metabolites, such as sesquiterpenes and other terpenes, steroids, anthraquinones, benzoic acid derivatives, and quinolines, but also primary metabolites such as oxalic acid. HMW compounds are mainly peptides and proteins. Data available from the literature indicate a higher antimicrobial activity of mushroom extracts against gram-positive bacteria. Among all the mushrooms, Lentinus edodes is the most studied species and seems to have a broad antimicrobial action against both grampostive and gram-negative bacteria. Plectasin peptide, obtained from Pseudoplectania nigrella, is the isolated compoundwith the highest antimicrobial activity against gram-positive bacteria, while 2-aminoquinoline, isolated from Leucopaxillus albissimus, presents the highest antimicrobial activity against gram-negative bacteria.