[Immunodepression and pulmonary infections]

The acquired immunosuppressed states are increasingly numerous. Pneumopathies are a frequent, serious complication and etiologic diagnosis is often difficult. The nature of the micro-organism in question is a function of the immunizing type of deficiency. In neutropenias, the infections are primarily bacterial, their potential gravity being correlated with the depth of the deficiency into polynuclear, or fungic, especially in prolonged neutropenias. The aspleened states are responsible for a deficit of the macrophage system and contribute to the infections with encapsulated germs (pneumococci, klebsiellas...). The organic grafts imply an attack of cell-mediated immunity, in the particular case of the auxiliary T lymphocytes (CD4)), with a special predisposition for viral and fungic infections. During VIH infection, the immunizing deficit of CD4 lymphocytes worsens with time. At the early stage, the infections are especially bacterial. At the more advanced stages, the pulmonary pneumocystosis and tuberculosis dominate. At the late stage, finally, deep immunosuppression allows emerging of the atypical mycobacteries. In the deficiencies of humoral immunity (congenital hypogammaglobulinemias, lymphoid hemopathies B), the germs to be mentioned are the pneumococcus, Haemophilus influenzae, the salmonellas and the legionellas. Immunosuppressed pneumopathies are characterized by radio-clinical pictures of very variable gravity, ranging from focused acute pneumopathy to bilateral diffuse pneumopathy with acute respiratory distress syndrome, with phases of atypical tables with respiratory symptomatology larval or absent. The highlighting of the micro-organisms in question requires urgent complementary investigations: hemocultures, bronchiolo-alveolar washing. In certain cases, it will be possible to resort to the transtracheal puncture or transthoracic puncture guided by tomodensitometry, and if necessary to pulmonary biopsy under videothoracoscopy. Emergency of the anti-infectious treatment imposes, in general, a presumptive treatment directed according to the immunizing deficiency in question and etiologic suspicion. It will be associated, if necessary, with urgent measurements of respiratory intensive care.