NPPA and ocular melanoma: For this purpose, we constructed and used a set of four Kp strains with variable efflux and OM barriers: the wild-type ATCC 43816 (Kp-WT), its efflux-deficient ΔtolC derivative (Kp-E), the hyperporinated Kp-P strain producing a large non-specific pore in the OM, and the double-compromised Kp-PE strains lacking the major efflux pump and carrying the hyperporinated OM.