Pyogenic infections

Pus formation requires an intact neutrophil response, so recurrent pyogenic infection points to specific immune defects, and the pattern of infection identifies which. Defects of antibody, such as X-linked (Bruton) agammaglobulinaemia and common variable immunodeficiency, cause recurrent sinopulmonary infection with encapsulated organisms after about six months of age, when maternal IgG wanes. Early complement component deficiencies (C1-C4) similarly impair opsonization and cause pyogenic infection plus a lupus-like syndrome, while terminal complement deficiency (C5-C9) specifically predisposes to Neisseria. Neutrophil disorders present differently: chronic granulomatous disease, from NADPH oxidase deficiency, causes infection with catalase-positive organisms and granuloma formation, diagnosed by dihydrorhodamine flow cytometry; leukocyte adhesion deficiency causes delayed umbilical cord separation, absent pus despite infection, and neutrophilia; and Chediak-Higashi syndrome, from a LYST mutation, causes giant granules, partial albinism, and neuropathy. Hyper-IgE (Job) syndrome causes cold staphylococcal abscesses, eczema, retained primary teeth, and coarse facies.