Staphylococcus epidermidis biofilm quantification: Effect of different solvents and dyes

•We compare DMSO, ethanol and methanol on bacterial biofilm formation.•We evaluate the sensitivity of safranin and crystal violet as biofilm dyes.•We evaluate decolorization of dyes by Staphylococcus epidermidis.•Methanol does not affect biofilm formation and safranin was the best dye.•DMSO and ethanol stimulates biofilm and crystal violet dye may mislead results.

Staphylococcus epidermidis biofilm formed in the presence of the solvents DMSO, ethanol or methanol was quantified using safranin or crystal violet staining protocols. We found that biofilm quantification was the most accurate when safranin protocol was applied. Moreover, both DMSO and ethanol stimulated biofilm formation.