OVERVIEW OF OPPORTUNISTIC INFECTIONS IN IMMUNOCOMPROMISED CHILDREN: ETIOLOGIES AND CLINICAL CHARACTERISTICS FOR PRACTICAL USE

Opportunistic infections (OIs) continue to be a significant cause of illness and mortality in children with malignant or nonmalignant conditions. OIs are defined as infections caused by bacteria, fungi, viruses, or normally harmless commensal organisms that inhabit the human body, but become pathogenic when the immune system is compromised. They may also present as unusually severe infections from common pathogens. In some cases, an OI can manifest as a life-threatening event at the onset of a primary immunodeficiency syndrome. More commonly, OIs arise as complications from immunosuppressive therapies, prolonged hospitalization, or in children undergoing bone marrow or organ transplants.