Immunocompromised children: conditions and infectious agents.

Individuals with immunodeficiency, either primary or acquired, are increasingly common. These individuals have increased susceptibility to a range of infections which are uncommon in the normal host. An understanding of the individual's immune defect provides important information about the range of organisms that this individual may be susceptible to. As a corollary, identification of an 'opportunistic pathogen' may indicate the patient's type of underlying immune defect.