Recurrent bacterial infection is a complaint encountered regularly in
the course of both adult and pediatric care. Defects of neutrophils an
d monocytes are most commonly associated with recurrent infection, but
abnormalities of immunoglobulins and complement must be considered. D
efensins, small antibacterial peptides, have been implicated recently
in some of the infectious diathesis of cystic fibrosis. A thorough his
tory and physical examination focused on severity, sequelae, and micro
biology of infections can usually determine whether a patient needs fu
rther evaluation. The diseases and syndromes most frequently associate
d with recurrent infection are presented, along with discriminating cl
inical, pathologic, and microbiologic features.