Effect of long-term primary aerosolized pentamidine prophylaxis on breakthrough Pneumocystis carinii pneumonia

Aerosolized pentamide is a well-tolerated primary prophylaxis regimen for Pneumocystis carinii pneumonia (PCP) in human immunodeficiency virus (HIV)-infected patients. It is now commonly administered for prolonged periods. We therefore studied the effect of long-term inhalation on breakthrough PCP. We recorded clinical, immunological, radiological and microbiological data, as well as therapy and clinical course of all episodes with confirmed PCP diagnosed at our institution between January 1, 1990 and June 30, 1995. Furthermore, data of all patients on primary aerosolized pentamidine since May 1, 1989 were retrieved. Prophylaxis failures were subdivided into "early" (< or = 12 months of inhalation time) and "late" (> 12 months of inhalation time) failures and were compared with episodes without any prophylaxis. Thirty patients without any prophylaxis, six with early and 14 with late failures represented the study population. Mean +/- SD inhalation times were 4.9 +/- 4.8 and 26.3 +/- 14.1 months, respectively. No significant differences could be detected with regard to clinical presentation, severity of PCP, and in-hospital as well as long term outcome. Early as well as late prophylaxis failures had a higher incidence of upper lobe infiltrates on chest radiography (50% without prophylaxis versus 100% with early and 83% with late failure, respectively; p < 0.05). No extrapulmonary or disseminated pneumocystosis was observed in either group. The sensitivity of site-directed bronchoalveolar lavage was conserved after long-term inhalation (86% versus 100% without prophylaxis and 97% in early failure; p = NS). The severity and outcome of Pneumocystis carinii pneumonia is not altered by long-term primary aerosolized pentamidine prophylaxis. Presentation with upper lobe infiltrates is a radiographic pattern also of late failures. Bronchoalveolar lavage should, therefore, be performed using the site-directed technique in this setting.