What is the main virulence factor of Escherichia coli O157:H7?

Escherichia coli O157:H7 is known for producing Shiga toxin, which is its principal virulence factor. Shiga toxin is a potent cytotoxin that inhibits protein synthesis in host cells, leading to severe damage, particularly in the intestinal lining. This results in bloody diarrhea and can lead to complications such as hemolytic uremic syndrome, a condition that can cause kidney failure. The presence of Shiga toxin in E. coli O157:H7 is a crucial factor in its pathogenicity and is responsible for the significant morbidity and mortality associated with infections caused by this strain.

The other factors mentioned, such as the capsule, endotoxin, and coagulase, are not primarily associated with E. coli O157:H7. While some strains of E. coli may produce capsules that provide protection against phagocytosis, E. coli O157:H7 specifically relies on Shiga toxin for its virulence. Endotoxin, which is a component of the Gram-negative bacterial cell wall, is not unique to this strain and is not a primary factor in its virulence. Coagulase, relevant in certain pathogenic staphylococci, does not apply to E. coli. Thus, the identification of Shiga toxin