The time course activity of Colistin and Imipenem on mucoid and non-mucoid biofilm-growing P. aeruginosa showed that compared with planktonic bacteria, the kinetics of Colistin and Imipenem retained the concentration- and time-dependent killings, respectively but higher doses of antibiotics and for longer periods were required for biofilm eradication. Biofilms of mucoid P. aeruginosa were more difficult to eradicate compared to non-mucoid biofilms.