Study of rapid diagnosis of enteric infections

肠道疾病快速诊断的研究细菌感染的快速诊断不仅对进行适当的治疗，而且对传染病的控制措施进行评估是十分必要的。目前诊断细菌感染的方法主要依赖于病原体的鉴定。然而，这种方法需要在诊断实验室获得标本后至少24-48小时。在本研究中，我们开发了两种快速鉴定方法：一种是免疫学方法，另一种是遗传方法。免疫方法珠状酶联免疫吸附试验检测肠道疾病致病菌毒素具有很高的灵敏度，可检出样品中20 ~ 100 mg/ml的致病菌毒素。因此，我们将该方法直接应用于印度加尔各答传染病医院收治的霍乱患者的粪便标本。结果表明，珠状酶联免疫吸附法测定霍乱毒素的灵敏度高于培养法，可在获得粪便标本4 ~ 5 h后诊断出霍乱患者。霍乱毒素基因的聚合酶链反应（PCR）是一种遗传方法，并直接应用于粪便标本。将粪便标本稀释50-100倍后，成功应用PCR，发现PCR在CPR、珠状酶联免疫吸附法和培养法3种检测方法中最敏感可靠。1992年10月，印度马德拉斯出现了新的霍乱疫情，并在整个印度和孟加拉国迅速蔓延。本研究建立的珠状酶联免疫吸附试验和PCR对追踪印度次大陆新型霍乱的出现具有重要意义。

Study on rapid diagnosis of enteric diseasesRapid diagnoses of bacterial infections are quite necessary not only to do an appropriate therapy but also to assess a control measure of infectious diseases. Current methods to diagnose bacterial infections depend mostly on identification of causative agents. However, this method requires at least 24-48 hours after the specimens become available at diagnosis laboratory. In this study, we developed two rapid identification methods : one is immunological method and the other is genetic method.The immunological method, bead-ELISA to detect the causative toxins of enteric diseases show a very high sensitivity and detect 20-100 mg/ml of the toxin in the samples. Thus, we applied this method direct to stool specimens of cholera patients admitted to Infectious Diseases Hospital, Calcutta, India. It was found that the bead-ELISA for cholera toxin was more sensitive than culture method and we could diagnose cholera patients 4-5 hours after the stool specimens became available.As a genetic method, polymerase chain reaction (PCR) of cholera toxin gene was developed and applied it directly stool specimens. After the stool specimens were diluted 50-100 times, PCR was successfully applied and it was found that the PCR was most sensitive and reliable among 3 methods examined, that is, CPR, bead-ELISA and culture method.In October 1992, a new cholera outbreak was emerged in Madras, India and it spread very quickly in whole India and Bangladesh. The bead-ELISA and PCR developed in this study was very useful to chase the appeared of this new cholera in Indian subcontinent.