FMO5 and pneumococcal infection: Oxidative stress can be triggered in neutrophils during pneumococcal infection from two primary sources: a) the S. pneumoniae pathogen itself is known to express significant levels of hydrogen peroxide [12], [13]; b) neutrophils produce super oxide radicals utilizing the NADPH oxidase complex resulting in increased hydrogen peroxide production, which is essential to the neutrophil's antibacterial activity [32].