Combination antimicrobial efficacy between the mushroom (Pleurotus ostreatus) and some commercial antibiotics

Susceptibility assays were carried out using four antibacterial and four antifungal commercial drugs against four pathogenic bacterial species and one pathogenic fungal species. The activity was compared with the antimicrobial activity of P. ostreatus mycelia extract. The results indicated high antimicrobial activity of mycelial extract against B. subtilis, E. coli, S. aureus and P. aeruginosa. B. subtilis was found to be the most susceptible to mycelial extract.

Ampicillin, Augmentin, Norfloxacin and Tetracycline exhibited lower activities than that of the mycelial extract against the pathogenic bacteria. The antifungal activity of mycelial extract against C. albicans detected lower values than that of Fluconazole, Amphotericin B, Terbinafine except Griseofulvin which achieved no antifungal activity on C. albicans. Antimicrobial assay of combination between P. ostreatus mycelial extract with the antibacterial Norfloxacin or the antifungal Terbinafine against B. subtilis or C. albicans, respectively, declared that macrodilution method is more sensitive than agar diffusion method in MIC determination. The tenfold dilution is more accurate than the bifold dilution in combination experiment. Three synergistic mixtures were explored in this study, Norfloxacin + P. ostreatus mycelial extract against B. subtilis (FICI=0.011) using macrodilution method; Norfloxacin + P. ostreatus mycelial extract against B. subtilis using agar diffusion method (FICI=0.11) and P. ostreatus mycelial extact + Terbinafine against C. albicans using macrodilution method (FICI=0.10001). These synergistic mixtures could be used in many technological applications include medicinal, pharmaceutical and food industries. This study also described that the antioxidant activity, protein and total phenol contents in P. ostreatus were higher than in carrot root used as standard plant.