Pneumocystis carinii: recognition of the infection in albino rats using different stains.

Pneumocystis carinii is a commensal protozoan which may cause pneumonia in hosts with compromised immune status and may end fatally. Since effective management of pneumocystic pneumonia depends on rapid and accurate recognition of the disease, so, the present study aims to throw lights on the best staining method for cytodiagnosis of this organism with the sequential pathological changes in the infected lungs. An immunosuppression state was induced in albino rats for 6-8 weeks then rats were sacrificed weekly & lungs were examined for infection using different stains. In stained smears, intracystic bodies have been identified using Giemsa, Papanicolaou & Toluidine blue stains. On the other hand, cysts were inspected in paraffin sections using Gomori methenamine silver nitrate (GMS) & weight gram stains. Histopathologically, in sections stained with H & E, features of Pneumocystis carinii pneumonia were obvious, foamy exudation, inflammatory infiltration formed mainly of histiocytes, plasma cells, lymphocytes, thickening of alveolar septa and lastly formation of hyaline membrane in some alveoli.