为寻找诊断肝硬化失代偿期并发自发性腹膜炎、胸膜炎和败血症时检测病原菌的方法。采用聚合酶链反应（ＰＣＲ）扩增真细菌域的１６ＳｒＲＮＡ基因，与Ｇｒａｍ阴性和Ｇｒａｍ阳性特异探针杂交检测肝硬化失代偿期患者胸腹水和血液中的致病菌。结果：ＰＣＲ腹水检测病原菌的阳性率９１４％；Ｇｒａｍ阴性探针斑点杂交（Ｄｏｔｂｌｏｔ）阳性率１００％；Ｇｒａｍ阳性杂交阳性率２１７％，高于细菌培养和鲎试验。结果提示：用ＰＣＲＤｏｔＢｌｏｔ杂交法检测病原菌的１６ＳｒＲＮＡ基因是诊断肝硬化自发性腹膜炎、胸膜炎和败血症等各种细菌感染的一种新方法 In order to find a method to detect pathogenic bacteria in patients with decompensated cirrhosis complicated by spontaneous peritonitis, pleurisy and septicemia. The 16S rRNA gene of eubacterial domain was amplified by polymerase chain reaction (PCR) and hybridized with Gram-negative and Gram-positive specific probes to detect the pathogens in the pleural, ascites and blood of patients with decompensated cirrhosis. Results: The positive rate of pathogen detection by PCR ascites was 914%. The positive rate of Dot blot of Gram negative probe was 100%. The positive rate of Gram positive hybridization was 217%, higher than that of bacterial culture and 鲎 test. The results suggest that using PCR-DotBlot hybridization to detect the 16SrRNA gene of pathogens is a new method to diagnose various bacterial infections such as spontaneous peritonitis, pleurisy and septicemia in cirrhosis