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以两对合成的不同寡核苷酸引物通过聚合酶链反应（ＰＣＲ）、扩增肠毒素大肠杆菌（ＥＴＥＣ）不耐热肠毒素（ＬＴ）和耐热肠毒素（ＳＴ）基因；两对引物从ＥＴＥＣＬＴ和ＳＴ基因中分别扩增出３１４ｂｐ，２３７ｂｐ的ＤＮＡ片段，均能与相应的ＬＴ和ＳＴ基因探针杂交。ＬＴ扩增产物（３１４ｂｐ）和ＳＴ扩增产物（２３７ｂｐ）分别和ＳｍａⅠ和ＨｉｎｃⅡ酶切后，产生１９０ｂｐ和１２４ｂｐ，１４７ｂｐ和９０ｂｐ的ＤＮＡ片段。同一扩增反应中应用ＬＴ和ＳＴ复合引物进行扩增，３种基因型ＬＴ、ＳＴ和ＬＴＳＴＥＴＥＣ从样品中鉴定出。１０９份动物腹泻粪样分别用ＰＣＲ，核酸杂交和ＥＬＩＳＡ进行测定，结果表明，ＰＣＲ是最为灵敏和快速的测定ＥＴＥＣ的方法。
The two pairs of synthetic oligonucleotide primers were used to amplify Enterotoxigenic Escherichia coli (ETEC) heat labile enterotoxin (LT) and heat-labile enterotoxin (ST) genes by polymerase chain reaction (PCR). Two pairs of primers 314bp and 237bp DNA fragments were amplified from ETECLT and ST genes, respectively, and could hybridize with corresponding LT and ST gene probes. After the LT amplification product (314bp) and the ST amplification product (237bp) were digested with SmaI and HincII, respectively, DNA fragments of 190 bp and 124 bp, 147 bp and 90 bp were generated. The same amplification reaction using LT and ST composite primer amplification, three genotypes LT, ST and LTSTETEC identified from the sample. 109 samples of animal diarrhea were detected by PCR, nucleic acid hybridization and ELISA, the results show that PCR is the most sensitive and rapid method for the determination of ETEC.