ABSTRACT
@#Abstract：Objective To investigate the morphological features of the Pneumocystis jirovecii, in order to facilitate early detection and rapid diagnosis of this rare pathogen from a morphology point of view by laboratory technicians. By analyzing the laboratory features and application value of different pathogen detection methods in the diagnosis of Pneumocystis jirovecii pneumonia, we aim to provide the most reliable diagnostic basis for rapid diagnosis of Pneumocystis jirovecii pneumonia.Methods A retrospective analysis was conducted on the test results of bronchoalveolar lavage fluid samples from a comprehensive hospital in Zhangqiu District, Jinan City, Shandong Province, and a hospital in Changde City from April 2022 to October 2022. Five confirmed cases of Pneumocystis jirovecii pneumonia were detected. Its clinical manifestations, laboratory results, and morphological characteristics of pathogens under different stains were analyzed to discuss the advantages and disadvantages of different detection methods. Results Cytological examination of bronchoalveolar lavage fluid found the trophozoites and cysts of Pneumocystis jirovecii by Wright's-Giemsa staining in 4 cases (80%), and the cysts of Pneumocystis jirovecii by Silver hexamine staining in 4 cases (80%), while the metagenomic next-generation sequencing confirmed all the 5 positive results. All 5 patients had different degrees of reduction in the absolute count of peripheral blood lymphocytes, and the serum lactic dehydrogenase and (1-3)-β-D-Glucan were increased. Among the 5 patients in this study, 4 were treated with sulfamethoxazole combined with caspofungin, and 1 was treated with sulfamethoxazole. Three patients were cured and discharged from hospital after treatment, but two died. Conclusions The method of Wright's-Giemsa staining for the cytological examination of bronchoalveolar lavage fluid to find Pneumocystis jirovecii has the unique and irreplaceable advantages as silver staining. Metagenomic next-generation sequencing can further increase the positive detection rate of Pneumocystis jirovecii. The combination of cytological examination of bronchoalveolar lavage fluid with metagenomic nextgeneration sequencing is a powerful diagnostic method for rapid diagnosis of Pneumocystis jirovecii pneumonia, which can diagnose accurately and reduce missed diagnosis.