Aims: This work aimed to screen the antimicrobial activity of aqueous
methanolic extracts of 13 mushroom species, collected in Braganc¸a, against
several clinical isolates obtained in Hospital Center of Tra´s-os-Montes and Alto
Douro, Portugal.
Methods and Results: Microdilution method was used to determine the
minimum inhibitory concentration (MIC) and the minimum bactericidal
concentration (MBC). MIC results showed that Russula delica and Fistulina
hepatica extracts inhibited the growth of gram-negative (Escherichia coli,
Morganella morganni and Pasteurella multocida) and gram-positive
(Staphylococcus aureus, MRSA, Enterococcus faecalis, Listeria monocytogenes,
Streptococcus agalactiae and Streptococcus pyogenes) bacteria. A bactericide effect
of both extracts was observed in Past. multocida, Strep. agalactiae and
Strep. pyogenes with MBC of 20, 10 and 5 mg ml
1, respectively. Lepista nuda
extract exhibited a bactericide effect upon Past. multocida at 5 mg ml
1 and
inhibited Proteus mirabilis at 20 mg ml
1. Ramaria botrytis extract showed
activity against Enterococcus faecalis and L. monocytogenes, being bactericide for
Past. multocida, Strep. agalactiae (MBCs 20 mg ml
1) and Strep. pyogenes
(MBC 10 mg ml
1). Leucopaxillus giganteus extract inhibited the growth of
E. coli and Pr. mirabilis, being bactericide for Past. multocida, Strep. pyogenes
and Strep. agalactiae.
Conclusions: Fistulina hepatica, R. botrytis and R. delica are the most
promising species as antimicrobial agents.
Significance and Impact of the Study: Mushroom extracts could be an
alternative as antimicrobials against pathogenic micro-organisms resistant to
conventional treatments.
