It's the rare, pathogenic strains that can cause bloody diarrhea, kidney disease, or death.

导致出血性腹泻、肾病或死亡的是极少数致病株。

To study how a pathogenic strain of E. coli behaves in this entire system, researchers had to build a replica.

为了研究大肠杆菌致病菌株在整个系统的行为，研究人员不得不复制了系统。