Clearance of Pneumocystis carinii Cysts in Acute P carinii Pneumonia

Assessment by Serial Sputum Induction

¹ From the Pulmonary/Critical Care Division, Brigham and Women's Hospital and Harvard Medical School, Boston, MA.
² From Microbiology Laboratory, Brigham and Women's Hospital and Harvard Medical School, Boston, MA.
³ From Renal Division, Brigham and Women's Hospital and Harvard Medical School, Boston, MA.
⁴ From Harvard Community Health Plan, Boston, MA.

Walter J. O'Donnell, MD, FCCP, Department of Medicine, AUH Allegheny General Hospital, 320 E North Ave, Pittsburgh, PA 15212; e-mail: wodonnel{at}aherf.edu

Study objectives: To determine the feasibility of repeat sputum induction in acute Pneumocystis carinii pneumonia (PCP) and to define the rate of clearance of P carinii cysts from the respiratory tract of HIV-seropositive patients with acute PCP.

Design: Prospective cohort evaluation.

Setting: University medical center.

Participants: Twenty-four HIV-seropositive subjects with acute PCP.

Measurements: Sputum induction for P carinii 2, 3, 4, and 6 weeks after initial diagnosis, and follow-up for 1 year.

Results: Eighty-eight percent of subjects had residual cysts at 2 weeks, 76% at 3 weeks, 29% at 4 weeks, and 24% at 6 weeks postdiagnosis. A prior AIDS-defining illness (p = 0.033) or prior PCP (p = 0.004) predicted relapse within 6 months, but persistent cysts at 3 weeks did not; 8 of 16 sputum-positive subjects and 1 of 5 sputum-negative subjects experienced a relapse within 6 months (p = 0.34). Secondary prophylaxis with trimethoprim-sulfamethoxazole was associated with a reduced risk of relapse.

Conclusions: Serial sputum induction coupled with direct fluorescent antibody staining is a feasible, noninvasive method of respiratory tract surveillance for the eradication of P carinii during and after acute PCP. Three-quarters of HIV-seropositive patients with acute PCP have persistent cysts in their lungs at the end of antimicrobial treatment, despite clinical recuperation, but only one quarter have residual cysts 6 weeks postdiagnosis. A prior AIDS-defining illness and prior PCP are positively associated, and subsequent trimethoprim-sulfamethoxazole prophylaxis is negatively associated, with relapse within 6 months, while persistent organisms at 3 weeks do not appear to be a significant predictor of relapse risk.

Key Words: HIV infection • Pneumocystis carinii pneumonia • sputum induction

Submitted on September 30, 1997
Accepted on June 30, 1998