Influence of extracellular DNA on antibiotic resistance in biofilms.

aBiofilms were cultivated and challenged in BM2 defined medium (2 mM Mg2+) with or without 0.75% (w/v) salmon sperm DNA, as indicated. bThe minimum inhibitory concentration (MIC) is defined as the lowest concentration of antibiotic required to inhibit the growth of planktonic cells that were shed from the peg. cThe minimum biofilm eradication concentration (MBEC) is defined as the lowest concentration of antibiotic required for complete killing of the surface-adhered biofilm. The MIC and MBEC values shown are the median values from four replicate experiments. PxnB = polymyxin B; Coln = colistin; Gm = gentamycin; Tm = tobramycin.