Pneumocystis carinii is diagnosed by

Pneumocystis infection - specimen is induced sputum, bronchoalveolar lavage or lung biopsy. On microscopy - trophozoites can be demonstrated by Giemsa , toludine blue, methenamine silver and calcofluor white stain. Ref: Textbook of Microbiology, Ananthanarayan and Paniker; 9th edition