Pulmonary colonization with Pneumocystis carinii in human immunodeficiency virus-negative patients: assessing risk with blood CD4+ T cell counts.

Abstract

Use of PCR analysis has led to detection of low numbers of Pneumocystis carinii organisms, which were undetectable by microscopy, in bronchoalveolar lavage (BAL) fluid specimens from immunosuppressed patients who showed no evidence of acute P. carinii pneumonia (PCP) (1). These low levels of par- asites were usually considered to reflect pulmonary coloniza- tion, but their significance was a subject of controversy. Cases of colonization were described mainly in patients positive for HIV who had blood CD4 1 T cell counts of /L (2). 6 ! 400 3 10 There were little data concerning HIV-negative patients (3). This study investigates the presence of P. carinii DNA in BAL fluid specimens from HIV-negative patients with no evidence of PCP and examines the link between colonization and decreases in blood CD4 1 T cell counts in this patient population.