Final answer:
Escherichia coli O157:H7 is a dangerous strain of E. coli associated with foodborne illnesses and outbreaks. It is characterized by its production of a Shiga toxin, which can cause severe diseases including hemorrhagic colitis and hemolytic uremic syndrome. Key virulence factors include surface antigens and toxins acquired through horizontal gene transfer.
Step-by-step explanation:
Escherichia coli O157:H7, a strain of E. coli, is significant due to its potential to cause serious foodborne illnesses. It has been involved in numerous disease outbreaks, originating from contaminated meat and produce.
This particular strain is categorized as enterohemorrhagic E. coli (EHEC), which can cause severe symptoms such as hemorrhagic colitis and hemolytic uremic syndrome, a life-threatening condition.
This strain possesses surface antigens, specifically the O antigen of the lipopolysaccharide and flagellar H antigen, which are used in its identification and are associated with its pathogenicity.
E. coli O157:H7 also produces a potent toxin, the Shiga toxin, which inhibits protein synthesis leading to cellular death. The genes for this toxin were acquired through horizontal gene transfer, likely from Shigella dysenteriae.
While many strains of E. coli serve beneficial roles in the human gut, helping with nutrient absorption, E. coli O157:H7 is one of the harmful strains due to the additional virulence factors it has obtained, including the ability to produce Shiga toxin and factors that promote colonization of the colon. These virulence factors can transform a commensal bacterium into a significant health risk.