pyocyanin

Pyocyanin, together with the yellow-green fluorescent pigment pyoverdine, produces the blue-green pus and the grape-like or corn-tortilla odour characteristic of Pseudomonas. It undergoes redox cycling, generating superoxide and hydrogen peroxide that injure epithelium, impair ciliary function, and induce neutrophil apoptosis, contributing to the chronic airway damage in cystic fibrosis. P. aeruginosa is an aerobic, oxidase-positive, non-lactose-fermenting gram-negative rod that thrives in moist environments, including hospital sinks, ventilators, and hot tubs. Its clinical signatures are examinable: ventilator-associated and cystic fibrosis pneumonia, where it forms alginate biofilm and adopts a mucoid phenotype; burn wound sepsis; malignant otitis externa in diabetics; osteomyelitis after a puncture wound through a sneaker; ecthyma gangrenosum, a necrotic black skin lesion in neutropenic sepsis; hot tub folliculitis; and corneal ulcers in contact lens wearers. Antipseudomonal agents include piperacillin-tazobactam, ceftazidime, cefepime, carbapenems other than ertapenem, aminoglycosides, and fluoroquinolones.