Complications involving the Kidney. Most E. coli strains can be contained by the intestinal lining – not so STEC pathogens, which are aggressive invaders. They tend to proliferate and then breach a section of the intestinal wall. This causes released toxins to be absorbed through the wall of the bowel. Once it actually enters the bloodstream, the Shiga toxin adheres to the body’s immune cells (white blood cells), and in adhering to them, reaches the kidneys. At this point, the infection becomes serious, as the kidney’s themselves become inflamed, and may fail.