Cresyl violet: a rapid, simple, easily interpretable stain for detecting Pneumocystis carinii in sputum

Over a three-month period at the pathology laboratory of Jackson Memorial Hospital, 110 sputum samples from 62 hospitalized patients with suspected AIDS were examined for Pneumocystis carinii. Sputum specimens were either expectorated spontaneously (most patients) or expectorated after the inhalation of small amounts of nebulized normal saline. Each sputum sample was cytocentrifuged onto two slides. One slide was stained with Gomori methenamine-silver (GMS) and the other with cresyl violet (CV). Among the 62 study patients, 18 were proven to have no histologic evidence of P carinii pneumonia. Of the remaining 44 patients, P carinii organisms were found by GMS stain in 14 (32%) and by CV stain in 18 (41%). Among those with a positive CV stain, the diagnosis was made on the first sputum specimen in 14 patients and on the second specimen in the remaining four patients. CV stain is at least as sensitive as GMS in detecting P carinii cysts in the sputum of AIDS patients with P carinii pneumonia, and its diagnostic sensitivity may exceed 40% under field conditions. Further, CV stain is much simpler to prepare than GMS and much simpler to interpret than Giemsa. It could be easily adapted for general use to expedite the diagnosis and treatment of P carinii pneumonia.