Violacein antimicrobial activity onStaphylococcus epidermidisand synergistic effect on commercially available antibiotics

Abstract

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.

Modulatory Effect of Lippia alba Essential Oil on the Activity of Clinically Used Antimicrobial Agents on Salmonella typhi and Shigella dysenteriae Biofilm

“…Considering the increasing bacterial resistance to multiple drugs, synergistic combinations between new molecules and commercial drugs could be good alternatives for the control of such microorganisms [27]. The advantages of combined therapies are the increase in antimicrobial activity, drug resistance prevention, and decrease in required doses, which can subsequently reduce costs, adverse effects, and drug toxicity [34].…”

“…After 15 min, the absorbance at 570 nm was measured using a microplate reader Bio-Tek (Winooski, VT, USA) [30]. The best association concentrations obtained with the Checkboard assay were added to the microplate wells [27]. The negative control of the experiment consisted of wells containing only TSB, and the positive control consisted of wells containing TSB and inoculum, without LaEO.…”

“…To determine cell viability, the biofilm from each well was resuspended in 0.85% saline solution and 5 µL aliquots of the serial dilutions of the biofilm suspensions were seeded on PCA. The best association concentrations obtained with the Checkboard assay were added to the microplate wells [27]. Two experiments were carried out in triplicate.…”

Antichagasic effect of violacein from Chromobacterium violaceum

“…The VIO used in this study was extracted from the C. violaceum ATCC 12472 strain, in the Laboratory of Molecular Genetics, purified and characterized in the Laboratory of Phytochemical Analysis of Medicinal Plants of the Federal University of Ceará (LAFIPLAN 1), as described by Dodou et al ().…”

“…Violacein has shown several biological actions, such as antiulcerogenic (Duran et al ), antiparasitic ( Trypanosoma , Leishmania and Plasmodium ) (Duran et al ; Leon et al ; Rahul et al ), antiviral (Andrighetti‐Fröhner et al ), antimicrobial (Batista et al ; Dodou et al ) and antitumour actions (Alshatwi et al ; Gonçalves et al ). These biological and pharmacological effects against micro‐organisms promoted the development of this study, aiming to evaluate the antichagasic effect of VIO, as well its action mechanism against T. cruzi.…”