Repurposing of escitalopram oxalate and clonazepam in combination with ciprofloxacin and sulfamethoxazole-trimethoprim for treatment of multidrug-resistant microorganisms and evaluation of the cleavage capacity of plasmid DNA.

Bacterial resistance has become one of the most serious public health problems, globally, and drug repurposing is being investigated to speed up the identification of effective drugs. The aim of this study was to investigate the repurposing of escitalopram oxalate and clonazepam drugs individually, and in combination with the antibiotics ciprofloxacin and sulfamethoxazole-trimethoprim, to treat multidrug-resistant (MDR) microorganisms and to evaluate the potential chemical nuclease activity. The minimum inhibitory concentration, minimum bactericidal concentration, fractional inhibitory concentration index, and tolerance level were determined for each microorganism tested. In vitro antibacterial activity was evaluated against 47 multidrug-resistant clinical isolates and 11 standard bacterial strains from the American Type Culture Collection. Escitalopram oxalate was mainly active against Gram-positive bacteria, and clonazepam was active against both Gram-positive and Gram-negative bacteria. When associated with the two antibiotics mentioned, they had a significant synergistic effect. Clonazepam cleaved plasmid DNA, and the mechanisms involved were oxidative and hydrolytic. These results indicate the potential for repurposing these non-antibiotic drugs to treat bacterial infections. However, further studies on the mechanism of action of these drugs should be performed to ensure their safe use.