A comparison of modified cytological and histological staining methods for the diagnosis of Pneumocystis carinii pneumonia.

The object of this study was to find a suitable staining method for P. carinii. This parasite is not easily stained and clinical signs are not specific for the diagnosis af P. carinii pneumonia and therefore optimal laboratory methods for observing the organism are extremely valuable. In all, 17 new, conventional and modified staining techniques were used on lung impression smears and tissue sections of Sprague-Dawley rats treated with cortisone (25% cortisone acetate, 1 ml injected twice weekly for 8 weeks). Of these methods modified methylene blue 1 & 2, modified cresyl violet 1, 2, 3, 4, modified Gram, modified Giemsa 2 and modified Griedley techniques have not previously been reported. After comparing readability of the slides, ease of performances, rapidity, availability and sensitivity of these 17 techniques for the diagnosis of P. carinii pneumonia, modified toluidine blue 0 1 & 2, modified methylene blue 1 & 2 and modified cresyl violet 3 & 4 are suggested as the methods of choice for the rapid diagnosis of P. carinii pneumonia.