PNEUMOCYSTIS-CARINII COLONIZATION IN THE ABSENCE OF IMMUNOSUPPRESSION

A prospective study was undertaken to evaluate the incidence and the c ourse of Pneumocystis carinii colonization in immunocompetent patients with severe pulmonary diseases. A further perspective was to determin e the diagnostic values of different detection methods. Bronchoalveola r lavage fluid samples from 77/838 adult HIV-negative patients were ex amined by Diff-Quik stain, direct immunofluorescence test and polymera se chain reaction. All Diff-Quik stains were negative, but direct immu nofluorescence tests and polymerase chain reactions were positive in t he samples of 5 patients. The normal number of granulocytes and CD4+ T -lymphocytes (median 810 cells/mu l) and normal values of immunoglobul ins proved the relative competence of the immune systems of the 77 pat ients. Although none of these patients received any agent effective ag ainst P. carinii, none developed a P. carinii pneumonia within a 120,5 -d surveillance period. Nosocomial transmission could be excluded, As the colonization with P. carinii did not result in pneumonia in immuno competent patients, clinically silent carriers have to be assumed, in non-AIDS patients, sensitive detection methods have to be used to iden tify colonized persons.