Effect of promethazine on biofilms of gram-positive cocci associated with infectious endocarditis.

This study evaluated the antimicrobial activity of promethazine against , and and its effect on the antimicrobial susceptibility of biofilms grown and on porcine heart valves. Promethazine was evaluated alone and in combination with vancomycin and oxacillin against spp. and vancomycin and ceftriaxone against in planktonic form and biofilms grown and . Promethazine minimum inhibitory concentration range was 24.4-95.31 μg/mL and minimum biofilm eradication concentration range was 781.25-3.125 μg/mL. Promethazine interacted synergistically with vancomycin, oxacillin and ceftriaxone against biofilms . Promethazine alone reduced ( < 0.05) the CFU-counts of biofilms grown on heart valves for spp., but not for , and increased ( < 0.05) the activity of vancomycin, oxacillin and ceftriaxone against biofilms of Gram-positive cocci grown . These findings bring perspectives for repurposing promethazine as adjuvant in the treatment of infective endocarditis.