Enterohemorrhagic E. coli at work

Date: June 1, 2011

From her laboratory, Olga Kovbasnjuk has  contributed this EM micrograph of an otherwise  normal, healthy enterocyte infected with the  O157:H7 strain of E. coli.  Samples of the bacteria  were collected from patients during an outbreak in Canada in 2000, in which people died from drinking  contaminated water. In the lab, the pathogens  were then introduced into enterocyte cultures.

This photo, for the most part, shows the normal apical brush border. The “elephant in the room,” however, is the large, infection-prompted “bleb” of actin, prior to its being reintegrated into the cell. Note the bacilli, which Kovbasnjuk says are excluded from being drawn into the enterocyte during the remodeling.  The large opening in the actin bleb “most certainly” would give entry to the Shiga toxin already excreted by this strain of E. coli into the intestinal lumen.