ABSTRACT
The aim of this study was to evaluate the antimicrobial potential of violacein (VIO) on Staphylococcus epidermidis biofilm. The minimum biofilm inhibition concentration (MBIC) and minimum biofilm eradication concentration (MBEC) were determined, as well as the effect of VIO exposure time on microbial viability in mature biofilm. Violacein showed good antibiofilm action, inhibiting biofilm formation and eradicating mature biofilm of S. epidermidis at concentrations of 20 µg.mL-1 and 160 µg.mL-1, respectively. At concentrations equal to MBEC and 2x MBEC, the biofilm was eradicated in 3 h and 2h30min of incubation, respectively.When evaluating VIO modulating effect on the action of clinically-used drugs (vancomycin, cefepime, ciprofloxacin and meropenem), especial synergism was observed in the violacein-ciprofloxacin association, it can completely erradicated the mature biofilm at the concentration of 1/2xMBEC and 1/4xMBEC, respectively. VIO shows good antimicrobial action on S. epidermidis biofilm and has the potential to synergistically modulate the activity of clinically-used antimicrobials.
Subject(s)
Staphylococcus epidermidis/drug effects , Anti-Bacterial Agents/pharmacology , Biofilms/drug effects , Dose-Response Relationship, Drug , Drug Synergism , Indoles/administration & dosage , Indoles/pharmacology , Microbial Sensitivity Tests , Vancomycin/pharmacologyABSTRACT
AIMS: The study aimed to assess whether violacein has antimicrobial activity on Staphylococcus epidermidis and synergistically modulates the action of commercially available antimicrobial drugs. METHODS AND RESULTS: Violacein showed excellent antimicrobial activity on biofilm-forming and nonbiofilm-forming S. epidermidis strains (ATCC 35984) (ATCC 12228), with bacteriostatic (MIC = 20 µg ml-1 and 10 µg ml-1 respectively) and bactericidal effects (MBC = 20 µg ml-1 for both strains), observed in short periods of exposure. The violacein bactericidal concentration led to S. epidermidis death after 2-3 h of exposure. Additionally, violacein synergistically modulated the activity of different antimicrobial classes on S. epidermidis ATCC 12228 (81·8%; n = 9) and on S. epidermidis ATCC 35984 (54·5%; n = 6), reducing the MIC of these antibiotics by up to 16-fold. CONCLUSION: Violacein shows excellent antimicrobial activity on S. epidermidis strains. SIGNIFICANCE AND IMPACT OF THE STUDY: Violacein shows the potential for the development of a new drug for the treatment of infections caused by S. epidermidis.
