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

Area of Science:

• Microbiology
• Pharmacology
• Infectious Diseases

Background:

• Infective endocarditis is a serious infection often caused by Gram-positive cocci like Staphylococcus and Streptococcus species.
• Biofilm formation on medical devices and heart valves contributes to treatment resistance.
• Novel therapeutic strategies are needed to combat antibiotic-resistant bacterial infections.

Purpose of the Study:

• To evaluate the antimicrobial activity of promethazine against Staphylococcus aureus, Staphylococcus epidermidis, and Streptococcus mutans.
• To assess promethazine's impact on the antimicrobial susceptibility of bacterial biofilms in vitro and ex vivo.
• To explore the potential of promethazine as an adjuvant therapy for infective endocarditis.

Main Methods:

• Minimum inhibitory concentration (MIC) and minimum biofilm eradication concentration (MBEC) assays were performed for promethazine alone and in combination with antibiotics.
• Biofilms were grown in vitro and ex vivo on porcine heart valves.
• Colony-forming unit (CFU) counts were used to quantify biofilm reduction.

Main Results:

• Promethazine exhibited antimicrobial activity with MICs ranging from 24.4-95.31 μg/mL and MBECs from 3.125-781.25 μg/mL.
• Synergistic interactions were observed between promethazine and vancomycin, oxacillin, and ceftriaxone against in vitro biofilms.
• Promethazine reduced Staphylococcus spp. biofilm counts on heart valves and enhanced the activity of tested antibiotics against ex vivo biofilms.

Conclusions:

• Promethazine possesses antimicrobial properties and can potentiate the efficacy of conventional antibiotics against bacterial biofilms.
• These findings support the potential repurposing of promethazine as an adjunctive treatment for infective endocarditis.
• Further research is warranted to explore promethazine's clinical utility in managing biofilm-related infections.