Application of Laser Modified Medicines in Fighting Multiple Drug Resistance Acquired by Microorganisms

The development of new medicines and alternatives to existing antimicrobial agents represents a high priority in treating infections caused by multidrug resistant bacteria. This is reported mainly, as multiple resistance acquired by bacteria at treatment with antibiotics. The use of laser radiation to photo-generate new compounds from known medicines can be an effective method to obtain a better antimicrobial activity against infections with bacteria and fungi. The irradiation with a laser beam emitted at 266 nm of 2 mg/ml aqueous chlorpromazine and thioridazine solutions for periods of time varying from 1 to 240 min leads to photochemical changes in the molecular structure of the parental compounds and to generation of new photoproducts with enhanced antimicrobial, antifungal and antibiofilm activity. The susceptibility of broad panels of Gram-negative and Gram-positive bacteria and fungi in planktonic and biofilm state, to the unirradiated and irradiated CPZ and TZ were performed in order to highlight the possible use of these substances for the development of novel antimicrobial agents. The antimicrobial activity was evaluated by quantitative methods, i.e. minimum inhibitory concentration and minimum biofilm eradication concentration assays. Both CPZ and TZ irradiated solutions presented, as cocktails of medicines obtained after laser irradiation, enhanced antimicrobial, antifungal and antibiofilm activity when compared to the unirradiated samples.

Keywords: ABC 230, Antimicrobial activity, Bacteria, Biofilm, Candida albicans, Chlorpromazine, Cryptococcus neoformans, Fungi, Klebsiella pneumoniae, Laser, MBEC, MDR, MIC, Multiple drug resistance, Pseudomonas aeruginosa, Susceptibility, Thioridazine, Staphylococcus aureus, UV laser radiation.