Moreover, S. parasanguinis in the presence of nitrite protects Drosophila from killing by P. aeruginosa during co-infections (Scoffield and Wu, 2015), and the nitrite reductase activity by P. aeruginosa is required for the survival of this pathogen during co-infection with S. parasanguinis (Scoffield and Wu, 2016), suggesting a new nitrite-dependent anti-infective mechanism by the oral commensal S. parasanguinis. The gene discussed is NGB; the disease is coinfection.