Rapid diagnosis of Pneumocystis carinii using dark-field microscopy on bronchoalveolar lavage. Brief report

20 lavages from patients with pulmonary infiltrates were microscopically studied by a rapid dark field assay and after methenamine silver staining. In 8 samples typical Pneumocystis carinii cysts were identified in the methenamine silver-slides and in 7 of these clusters of round spawn-like particles were also seen in the dark field microscope. One test was "false negative" in the dark field assay due to presence of too few pneumocystes. Another test was "false positive" due to presence of candida albicans spores in the lavage. It is thus possible to give a Pneumocystis carinii diagnosis, with some reservation, within 15 minutes after obtaining the bronchoalveolar lavage.