In this study, we examined the co-localization of NE, MPO, and CatD with the phagosome of CF-sputum-treated PMNs after MRSA24 infection, in which the presence of these proteins illustrates that phagolysosome fusion occurred to enable their release inside the phagosome to co-localize with MRSA. The gene discussed is MPO; the disease is cystic fibrosis.