[Respiratory infections during chemotherapy-induced aplasia]

Damage to local and systemic host defenses of the lung makes the immunocompromised patient vulnerable to inhaled microorganisms. When a pulmonary infiltrate occurs, the array of possibilities is very large including conventional and opportunistic agents. The type of underlying disease and its associated immunodeficiency allow a high degree of accurate pathogen prediction. Neutropenia is associated with Gram-negative bacilli pneumonia. Prolonged neutropenia increases the risk of invasive aspergillosis and other unusual mycotic agents. Cellular immunodeficiency is associated with intracellular microorganisms including Mycobacteria spp., Nocardia spp., Legionella spp., Rhodococcus equi, cytomegalovirus, Strongyloides stercoralis, Toxoplasma gondii, Histoplasma capsulatum, Coccidioides spp., Cryptococcus neoformans and Pneumocystis carinii, parasites such as Toxoplasma gondii and Strongyloides stercoralis, and virus such as cytomegalovirus, Herpes simplex or zoster, adenovirus, respiratory syncitial virus and measles. Humoral immunodeficiency predisposes to infection with encapsulated pathogens such as S. pneumoniae and Haemophilus influenzae. Chest computerized tomography scan and bronchoalveolar lavage are essential procedures for diagnosis. However, despite continuous progress in diagnostic methods, the specific etiology remains often unknown. Successful treatment depends on the type of pathogen, status of host defences and early adequate choice of antibiotic. Enhancement of host defences with growth factors and cytokines may decrease the incidence and improve the final outcome of respiratory infections in the immunocompromised host.