Study objective: To determine the relative distribution of Pneumocystis carinii in the lungs of patients with P carinii pneumonia and to see the effect of aerosol pentamidine prophylaxis on this distribution.
Design: A prospective study of all human immunodeficiency virus-infected patients with pulmonary symptoms over a nine-month period. Patients were followed up for at least six weeks after bronchoscopy.
Setting: Inpatient and outpatient service at one referral center.
Patients: Human immunodeficiency virus-infected patients with pulmonary symptoms were referred for evaluation. Those patients subsequently found to have P carinii pneumonia were studied.
Intervention: Bronchoalveolar lavage was performed in the middle lobe (or lingula) and the apical segment of the same lung.
Measurements and results: The aspirated fluids were kept separate and modified Wright-Giemsa-stained cytocentrifuge-prepared slides were made from each area, and the number of P carinii clusters per 500 nucleated cells was counted. Fifty patients were studied: 27 receiving pentamidine prophylaxis and 23 receiving no aerosol therapy. There was no significant difference in the amount of fluid retrieved by lavage from the middle or upper lobe for either group. Both groups had significantly lower numbers of P carinii clusters per 500 cells in the middle lobe (receiving pentamidine: 10 +/- 15.8 [SD]; not receiving pentamidine: 15 +/- 12.3) than in the upper lobe (receiving pentamidine: 22 +/- 19.8; not receiving pentamidine: 24 +/- 21.5; p < 0.02). In six patients, there were no P carinii organisms seen in the middle lobe lavage specimen.
Conclusion: Pneumocystis carinii has a preference for the upper lobes which may be apparent even in patients not receiving aerosol pentamidine. In addition, yield for P carinii may be increased by performing lavage in the apical segment.