Screening for Antibacterial Activity of French Mushrooms against Pathogenic and Multidrug Resistant Bacteria

Abstract

In the alarming context of antibiotic resistance, we explored the antibacterial potential of French mushrooms against wild-type and multidrug-resistant (MDR) bacteria. In order to accelerate the discovery of promising compounds, screenings were carried out by TLC-direct bioautography. A total of 70 extracts from 31 mushroom species were evaluated against five wild-type bacteria: Staphylococcus epidermidis, Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, and Pseudomonas aeruginosa. This first screening revealed that 95% of the extracts contained antibacterial compounds. Generally, it was observed that EtOAc extracts exhibited more active compounds than methanolic extracts. In addition, all extracts were overall more active against Gram-positive bacteria than against Gram-negative strains. The most promising mushroom extracts were then screened against various multidrug-resistant strains of S. aureus and E. coli. Activity was globally less on MDR strains; however, two mushroom species, Fomitopsis pinicola and Scleroderma citrinum, still contained several compounds inhibiting the growth of these MDR pathogenic bacteria. Stearic acid was identified as a ubiquitous compound contributing to the antibacterial defence of mushrooms. This screening revealed the potential of macromycetes as a source of antibacterial compounds; further assays are necessary to consider fungal compounds as promising drugs to counter antibiotic resistance.