pyocyanin

noun

pyo·​cy·​a·​nin ˌpī-ō-ˈsī-ə-nən 

variants or pyocyanine

-ˌnēn 

: a toxic blue crystalline pigment C₁₃H₁₀N₂O that is formed in the metabolism of a bacterium of the genus Pseudomonas (P. aeruginosa), gives a bluish tint to pus infected with this organism, is a quinone imine related to phenazine, and has antibiotic activity especially toward gram-positive bacteria