COMPARISION OF IMPRESS SMEARS AND TISSUE SECTION STAINED WITH DIFFERENT METHODS FOR DIAGNOSING OF PNEUMOCYSTIS CARINII

摘要

Background & Aims : Pneumocystis carinii is an opportunist extracellular microorganism. The body can defend itself against it in natural conditions. But it can cause an infection in immunodificient conditions such as HIV, Hodgkins and other immunosuppressed diseases. The aim of this study was to apply a comparison of different staining methods such as Methenamine silver, Giemsa, Gram - Weigert, Papanicolaou and Hematoxylin eosin stains in terms of staining times, easiness, cost and availability of material and methods, detection of P. carinii, different forms and capability of this methods in detection of P. carinii in impression slides, and tissue slices of rats lungs. Materials & Methods : In order to induce of Pneumocystis pneumonia, the Sprague Dawley rats were injected 0.5cc of dexamethasone subcutaneously twice a week over a 10-12 weeks, after induce pneumonia we removed the lungs and made impression slides and pieces of lung was put in 10% formalin to make tissue slides. After that the slides stained by Methenamine silver, Gram Weigert, papanicolaou, Giemsa and Hematoxylin eosin, and compared them in terms of staining time, easiness, cost and availability. In addition, we compared the capability of different methods to detect the microorganism in tissue preparation slices and impression slides. Results : Giemsa and papanicolaou are capable to stain the intra cyst bodies but can’t stain the cysts wall. Methenamine silver and Gram Weigert stain the cysts wall. Giemsa is fastest, cheapest and the most easy method to stain, vs. methenamine silver is expensive, difficult and takes long time to do. Methenamine silver papanicolaou, Gram Weigert can detect P. carinii in both tissue slice and smears but Hematoxylin eosin can’t detect either slices or impression slides. Giemsa only detects microorganism in impression slides. Conclusions : In these staining methods, Papanicolaou and Giemsa have more specificity than Gram Weigert to detect the P. carinii in specimens, because these staining method don’t specify the wall of cysts together with yeasts, because of this the wrong diagnosis with Giemsa and Papanicolaou is less than Gram Weigert. Methenamine silver is golden standard method to detect P. carinii but it stains the yeasts like P. carinii because the yeasts are similar to cysts in shape and color when we stain with methenamine silver. Because of this we conclude that Methenamine silver is suitable and useful for demonstration of P. carinii cysts but it is better to be used together with Giemsa, because Giemsa can stain the intra cyst bodies so the diagnosis of pneumocystis pneumonia becomes easy with these methods together.