This girl has chronic granulomatous disease, in which the immune system cannot properly form reactive oxygen species needed to kill phagocytosed organisms. This is especially bad when dealing with catalase positive organisms (like Staph), because these organisms already use catalase to break down reactive oxygen species. The most common cause of this condition is a mutation in NADPH oxidase, responsible for the generation of the superoxide radical.

NADPH def: CGD --> infections with catalase + (SNAPS - staph species, nocardia (NOT actinomyces), aspergillus, pseudomonas (esp cepacia), serrate marcescens) ~ Dihydrorhodamine or nitroblue tetrazolium testing MPO def: candida infections, responsible fro green colour of sputum