The question stem is describing a boy with chronic granulomatous disease (CGD). CGD patients lose NADPH oxidase - resulting in an inability to make hydrogen peroxide. Hydrogen peroxide is needed by neutrophils and macrophages to kill bacteria. It just so happens that bacteria make their own hydrogen peroxide. Catalase (-) pathogens release their hydrogen peroxide when phagocytosed, essentially giving the host immune cells a weapon that can be used to eradicate these types of infections. But CGD patients cannot kill Catalase (+) organisms, like S. aureus, because the bacterial catalase enzyme destroys any bacterially produced hydrogen peroxide.
submitted by โiceberglettuce(15)
The question stem is describing a boy with chronic granulomatous disease (CGD). CGD patients lose NADPH oxidase - resulting in an inability to make hydrogen peroxide. Hydrogen peroxide is needed by neutrophils and macrophages to kill bacteria. It just so happens that bacteria make their own hydrogen peroxide. Catalase (-) pathogens release their hydrogen peroxide when phagocytosed, essentially giving the host immune cells a weapon that can be used to eradicate these types of infections. But CGD patients cannot kill Catalase (+) organisms, like S. aureus, because the bacterial catalase enzyme destroys any bacterially produced hydrogen peroxide.