Effect of efflux pump inhibitors on P. aeruginosa strain PAO1 (A) and clinical isolate PAmuc (B) 72-h biofilms. Efflux pump inhibitors NMP, CCCP, Cpz, and PAβN were added at 200, 50, 50, and 50 mg/liter, respectively. Star, significant difference at P = 0.05 from biofilm treated only with respective concentration of glutaraldehyde.