FIG. 3.

Difference of S. epidermidis counts in log₁₀ (CFU/well) between unchallenged and challenged 24-h biofilms as measured by bioluminescence. Challenged biofilms were exposed for 24 h to the transcription inhibitors at concentrations ranging from 1× MIC to 16× MIC. The mean bacterial amount within the unchallenged biofilm was 6.55 ± 0.02 log₁₀ CFU/well. The dashed line represents the difference of counts after challenge with ciprofloxacin at 20 μg/ml for 24 h. The mean value of the bacterial count ± the standard error is given. RIF, rifampin; RFP, rifapentine; RFX, rifaximin; STL, streptolydigin; LIP, lipiarmycin; THL, thiolutin; HOL, holomycin; URT, ureidothiophene.