https://doi.org/10.17113/ftb.64.02.26.9283

Article in press

Ethyl Acetate Extracts of Edible Mushroom Species Enhance β-Lactam Activity Against an MRSA Isolate in vitro

James Blee, Peter O’Hara, Thomas Smyth and Owen Kenny^*

Department of Health and Nutritional Science, Atlantic Technological University, Sligo, Ireland

Copyright © 2024 This is a Diamond Open Access article published under CC-BY licence. Copyright remains with the authors, who grant third parties the unrestricted right to use, copy, distribute and reproduce the article as long as the original author(s) and source are acknowledged.

Food Technol. Biotechnol. 2026; 64(2).

Article history:

Received: 24 July 2025

Accepted: 16 March 2026

Keywords:

antibiotic modulation; edible mushrooms; MRSA; beta-lactams; Agaricus bisporus; antimicrobial resistance

Summary:

Research background. The accelerated emergence of antimicrobial resistance (AMR) has led to numerous pathogens developing resistance to available antibiotics. Staphylococcus aureus is a leading cause of hospital-acquired infections, and the emergence of resistant strains like methicillin-resistant Staphylococcus aureus (MRSA) has led to greater clinical complications and higher mortality rates. As such, restoration of first-line β-lactam antibiotic activity is a viable strategy to combat AMR. The antimicrobial activity of edible mushroom extracts is well reported; however, their use as a source of antibiotic modulators is relatively unexplored, while current reports often do not adhere to drug combination guidelines. The aim of this study was to evaluate the potential of extracts derived from 10 edible mushroom species to modulate β-lactam antibiotics against MRSA with reference to the recommended guidelines.

Experimental approach. Antimicrobial activity (minimum inhibitory concentration (MIC)) and antibiotic-modulating activity (fractional inhibitory concentration index (FICI)) were assessed using the broth microdilution method. The cell viability assay was used to assess cell membrane integrity following treatment to offer insight into potential mechanisms of action.

Results and conclusions. Both antimicrobial and antibiotic modulatory activity solely resided in ethyl acetate extracts. Hericium erinaceus extract demonstrated the strongest antimicrobial activity against S. aureus (MIC=0.8 mg/mL), while Agaricus bisporus extract exhibited the strongest antibiotic-modulating properties, exhibiting a x25-fold reduction in ampicillin, amoxicillin and penicillin MIC against an MRSA isolate (FICI=0.29), indicating synergism. The mechanism of action indicates reduced cell membrane integrity, which may increase intracellular antibiotic concentration.

Novelty and scientific contribution. These results indicate the potential utilisation of ethyl acetate extracts derived from edible mushrooms as a source of antibiotic-modulating compounds, namely A. bisporus. To our knowledge, this is the first study to evaluate the antibiotic-modulating effects of H. erinaceus, Hypsizygus tessulatus and Pholiota adiposa. This study also highlights the necessity to adhere to FICI guidelines when evaluating the antibiotic-modulating potential of edible mushroom extracts.