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Table 2 Minimal biofilm inhibitory and eradication concentrations (MBIC and MBEC) determined by resazurin and cell counting methods

From: Defining conditions for biofilm inhibition and eradication assays for Gram-positive clinical reference strains

Bacterial strain Antibiotic MICa (μg/mL) MBIC (μg/mL) MBEC (μg/mL)
Resazurin CFU/mLb Resazurin CFU/mLb
(decrease in RFU) (growth inhibition) (decrease in RFU) (log10 reduction)
Staphylococcus aureus ATCC 29213 Ciprofloxacin 0.5 1 (99%) 1 (100%) >  160 (18%) >  160 (1.2)
Staphylococcus aureus MRSA ATCC 43300 Ciprofloxacin 0.5 1 (99%) 1 (100%) >  160 (30%) >  160 (1.7)
Enterococcus faecalis ATCC 29212 Ciprofloxacin 1 1 (90%) 1 (100%) >  160 (35%) >  160 (4.0)
Enterococcus faecalis VRE ATCC 51575 Ciprofloxacin 0.5 1 (99%) 1 (100%) >  160 (0%) >  160 (3.3)
Enterococcus faecium ATCC 35667 Linezolid 4 2 (96%) 2 (100%) >  80 (26%) >  80 (1.5)
Enterococcus faecium VRE ATCC 70021 Linezolid 2 2 (99%) 2 (97%) >  80 (26%) >  80 (1.8)
  1. Mean of quality parameters of MBIC and MBEC assays were: Z’ = 0.83; S/B = 14.83, SW = 36.40 and Z’ = 0.77; S/B = 21.19 and SW = 17.19, respectively
  2. a:Minimal inhibitory concentration previously determined by our group
  3. b:For each experiment, initial biofilm cell populations were determined and used for the calculations of growth inhibition and log10 reduction