Nosocomial Infections: Pathogenicity, Resistance and Novel Antimicrobials

Antimicrobial Activity of Fomitopsis Officinalis (Vill.) Bondartsev & Singer in Pure Culture

Background. According to the World Health Organization antibiotic resistance is among the top ten threats to human health, food safety and development. Today antibiotic resistance has reached alarmingly high levels all over the world. Meanwhile, the increase in the synthetic drugs' production has led to the pathogenic mycobiota's rapid adaptation to the created chemicals, which have a narrow focus of application. That is why in modern biotechnology and pharmacology much attention is paid to natural producers of biologically active compounds, in particular – to xylotrophic fungi. It has been experimentally proven that the xylotrophic macromycete Fomitopsis officinalis or tinder fungus can be considered to be a promising producer of pharmacological substances with a broad spectrum of action. Studies of active metabolites, contained in the mycelial mass, culture fluid of the medicinal xylotrophic macromycete F. officinalis, and determination of their biological action remain relevant. Objective. The objective was to determine the antimicrobial activity of culture fluid and mycelial mass of F. officinalis different strains from the mushrooms collection (IBK Mushroom Culture Collection of the M.G. Kholodny Institute of Botany, NAS of Ukraine) against gram-negative and gram-positive bacteria species. Methods. An in vitro study of the antimicrobial activity of ethyl acetate extracts of culture fluid and aqueous-ethyl extracts of mycelial mass for F. officinalis strains IBK-5004, IBK-2497, IBK-2498 against gram-positive Staphylococcus aureus (B-918), Bacillus subtilis (В-901) and gram-negative Escherichia coli (B-906), Bacillus subtilis (B-900), Klebsiella pneumoniae (M-123) bacteria by disc-diffusion method was conducted. Results. High antimicrobial activity of tinder fungus culture fluid and mycelial mass extracts against Staphylococcus aureus was established after the 21st day of cultivation, while on the 28th day the zone of growth retardation was maximal (15–25 mm). The highest indices were recorded in F. officinalis IBK-5004 (20–25 mm) and IBK-2498 (20–24 mm) strains. Antimicrobial activity against Klebsiella pneumoniae in culture fluid extracts was manifested on the 21st and 28th days of cultivation. The highest antimicrobial activity against Klebsiella pneumoniae was observed in the culture fluid of the strain F. officinalis IBK-5004, the diameter of the growth retardation zone was 18 mm on the 28th day of cultivation. Mycelial mass's extracts showed moderate activity on the 14th day of cultivation (7-8 mm); maximal activity was recorded on the 28th day (12–22 mm). The most active strain was Fomitopsis officinalis IBK-2498. No antimicrobial activity against test organisms was detected in the following studied strains: Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis. Conclusions. It has been established that the mycelial mass and culture fluid extracts of F. officinalis IBK-5004, IBK-2497, IBK-2498 strains have high antimicrobial activity against Staphylococcus aureus and moderate antimicrobial activity against Klebsiella pneumoniae on the 21st and 28th day of cultivation.