Evaluation of the inhibitory effects of TiO 2 nanoparticle and Ganoderma lucidum extract against biofilm-producing bacteria isolated from clinical samples

The emergence of multidrug-resistant pathogens leads to treatment failure. So, the need for new antibacterial drugs is urgent. We evaluated the antibacterial and antibiofilm effects of titanium dioxide (TiO 2 ) nanoparticles (NPs) and Ganoderma extract against biofilm-producing Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus (MRSA) by microbroth dilution and crystal violet assays. The combined effect of these compounds was studied using the checkerboard method. The OD 260 was measured to assess the destruction of the membrane permeability. The expression of biofilm-related genes ( iacA and algD ) was investigated by real-time PCR. MRSA isolate was more susceptible to test compounds. The OD 260 increased and algD gene was down-regulated after treatment with TiO 2 NPs and a combination of TiO 2 NPs and Ganoderma extract. iacA gene did not affect by test compounds. Overall, these findings revealed that nanoparticles and natural substances might represent the potential candidates to develop promising antibacterial agents, especially against Gram-positive bacteria.