Pneumocystis carinii pneumonia in patients with AIDS: evaluation of lavage and staining techniques in diagnosis.

The diagnostic yield of unilateral vs. bilateral bronchoalveolar lavage (BAL) was prospectively evaluated in 65 consecutive patients suspected of having Pneumocystis carinii pneumonia (PCP) complicating acquired immune deficiency syndrome (AIDS). Gram-Weigert (GW), Papanicolaou (PAP), and Gomori's methenamine silver (GMS) stains were used for identification of P. carinii in all cases. Forty-eight patients had PCP that was identified by GW staining of BAL in 47/48 patients followed by PAP/GMS staining of BAL in 44/48 patients and PAP/GMS staining of bronchial washings in 40/48 patients. In patients with bilateral interstitial infiltrates, unilateral lavage was sufficient for diagnosis of PCP when GW stain was utilized. In patients with PCP complicating AIDS, the diagnostic yield of BAL may be increased by use of both GW and GMS stains.