Pneumocystis carinii identified by gram stain of lung imprints.

The diagnosis of Pneumocystis carinii pneumonia conventionally depends on the time-consuming demonstration of the organisms in pulmonary secretions or lung tissue using toluidine blue 0, methenamine silver, or Gram Weigert stains that require special reagents. In 27 recent episodes of moderate to heavy pneumocystis infections, the cyst form and internal sporozoites of P. carinii could be readily identified on lung imprints using the conventional Gram stain. The Gram stain is unlikely to replace special stains for the diagnosis of pneumocystosis, but it does provide a rapid method to recognize moderate to heavy infections.