<prompt> Which of the following strains of Escherichia coli is commonly implicated in travelers diarrhea mediated by heat stable enterotoxin and heat labile exotoxin?EnterotoxigenicEnteroinvasiveEnteropathogenicEnterohemorrhagic  <response>: Enterotoxigenic Escherichia coli ETEC is common cause of travelers diarrhea. It is also associated with diarrhea in infants in developing countries. It causes watery diarrhea, abdominal cramps and low grade fever. The common etiologies of travelers diarrhea may vary with location and with season. However, on a world-wide basis, the organism most frequently identified in patients with travelers diarrhea is enterotoxigenic Escherichia coli. This organism accounts for between 30 and 70 of all cases of travelers diarrhea. Transmission is usually through food or water that is fecally contaminated. The virulence factor implicated are as follows: Heat stable enterotoxin stimulates fluid secretion by activating guanylate cyclase in enteric epithelial cells. Heat labile exotoxin binds to the ganglioside at the brush border of epithelial cells of small intestine and leads to activation of adenylate cyclase. Colonization factors facilitate the attachment of ETEC to epithelial cells of intestine. Ref: Textbook of Microbiology ANANTHANARAYANAN, 8th Ed, page 274-277 