Biofilm formation assay for the cpKP isolates. A. Side views of the test tubes with biofilms at 24 h after crystal violet staining. Eight isolates (namely G275, G209, G504, G213, G284, G282, G277, and G281) were randomly selected from our 420 cpKP isolates, and NTUH-K2044 was included as positive control. B. Quantitative calculation of biofilm product for the isolates at the 24 h post staining. The biofilm production was calculated by 1000×OD570/(OD600×V1×V2); V1 refers to the volume of initial bacterial solution, and V2 refers to the volume of DMSO.