Through their ability to strengthen the host immune response, fungal polysaccharides increase resistance and reduce incidences of post-surgical infection1. In addition, mushrooms have evolved a range of defences against other competing micro-organisms and several show direct anti-microbial action.
When aqueous extracts of Lentinula edodes and Pleurotus ostreatus were tested against a panel of 29 bacterial and 10 fungal pathogens, L. edodes extract showed extensive antimicrobial activity against 85% of the organisms, including 50% of the yeast and mould species, while aqueous extracts of P. ostreatus showed 87.5% inhibition against E. coli and 57.5% against B. subtilis2. In a study of over 200 species of mushroom in Spain almost 50% had direct antibiotic activity against a range of test organisms3.
Extracts of both Hericium erinaceus fruiting body and mycelium exhibited anti-MRSA activity with erinacines identified as active compounds. In clinical tests in Japan MRSA was seen to disappear in a number of patients given H. erinaceus4. Similar cyathane type compounds from other mushroom species also show antibiotic potential5, while the traditional use of H. erinaceus in the treatment of gastritis (now known to be caused in many cases by the bacteria H. pylori) supports its antibacterial action.
In vitro studies using organic Ganoderma lucidum extracts also showed anti-MRSA activity while the use of G. lucidum hot-water extracts together with conventional antibiotics (ampicillin, ciprofloxacin, streptomycin, kanamycin and cephotaxamine) enhanced antibacterial activity compared with the antibiotic alone6,7.
CLINICAL NOTE
Traditionally H. erinaceus fruiting body has been used but the fact that mushroom antimicrobial compounds are predominantly secreted into the growth substrate supports clinical use of mycelial biomass. Dosage of fresh fruiting body prescribed in the Chinese Pharmacopoeia is 25-50g/day (equivalent to 2.5-5g dried).
REFERENCES
1. Potential of the beta-glucans to enhance innate resistance to biological agents. Thompson IJ, Oyston PC, Williamson DE. Expert Rev Anti Infect Ther. 2010;8(3):339–352.
2. An examination of antibacterial and antifungal properties of constituents of Shiitake (Lentinula edodes) and oyster (Pleurotus ostreatus) mushrooms. Hearst R, Nelson D, McCollum G, Millar BC, Maeda Y, Goldsmith CE, Rooney PJ, Loughrey A, Rao JR, Moore JE. Complement Ther Clin Pract. 2009;15(1):5–7.
3. Screening of Basidiomycetes for antimicrobial activities. Suay I, Arenal F. Antonie van Leeuwenhoek. 2000;78:129–139.
4. Anti-MRSA compounds of Hericium erinaceus (Bull.:Fr.) Pers. Kawagishi H. Int J Med Mushrooms. 2005;7(3):350.
5. Two cyathane-type diterpenoids from the liquid culture of Strobilurus tenacellus. Shiono Y, Hiramatsu F, Murayama T, Koseki T, Funakoshi T. Chem Biodivers. 2008;5(9):1811–1816.
6. Antibacterial activity of the bio-multidrug (Ganoderma lucidum) on Multidrug resistant Staphylococcus aureus (MRSA). Prasad Y, Wesely WEG. Advanced Biotech. 2008;10:9–16.
7. Naturally occurring medicinal mushroom-derived antimicrobials: a case-study using Lingzhi or Reishi Ganoderma lucidum (W. Curt.:Fr.) P. Karst. (higher Basidiomycetes). Karwa AS, Rai MK. Int J Med Mushrooms. 2012;14(5):481–490.