Role of special stains in the diagnosis of Pneumocystis carinii infection from bronchial washing specimens in patients with the acquired immune deficiency syndrome

Fifty bronchial washing specimens from 36 patients with acquired immune deficiency syndrome (AIDS) were retrospectively reviewed to assess the sensitivity of the various special stains used to diagnose Pneumocystis carinii. In 76% of the cases, the Diff-Quik stain was positive; it was the easiest and most rapid of the special stains used. The sensitivity was increased to 92%, 96% and 100%, respectively, by also doing cresyl echt violet, Grocott's Gomori methenamine silver and both the cresyl violet and Grocott stains in addition to the Diff-Quik stain. We conclude that the Diff-Quik stain is a fairly reliable and rapid screening procedure for making the diagnosis of Pneumocystis infection in bronchial washings from AIDS patients. The routine Papanicolaou stain gave less sensitive results in the smears of the washing specimens, but does give a markedly improved yield in bronchoalveolar lavage specimens.