FIG. 2.

NTZ inhibition of S. epidermidis growth and biofilm production. (A) MIC testing. Biofilm-forming strain 9142 (▪) and non-biofilm-forming strains 5179 (⧫) and CAV1005 (•) were tested for their susceptibilities to NTZ by microdilution, and bacterial growth was measured by measurement of the turbidity, as described in the text. (B) Aerobic growth. Bacteria were grown in TSB medium with shaking at 37°C in the presence of no NTZ (⧫), 10 μg/ml NTZ (▪), or 25 μg/ml NTZ ▴). (C) Biofilm inhibition by NTZ. Staphylococcus strains were grown in the presence of different concentrations of NTZ in 96-well polystyrene plates and subjected to crystal violet staining after 24 h, as described in the text. The biofilm-positive strains (see the key) used were S. epidermidis 9142 and S. haemolyticus S33208, and the biofilm-negative strains were S. hominis F13532 and S. epidermidis CAV1005. The IC₅₀ for biofilm-producing strains was 2.5 μg/ml.