Which strain of E. coli is commonly referred to as Enterotoxigenic E. coli (ETEC)?

Which strain of E. coli is commonly referred to as Enterotoxigenic E. coli (ETEC)?

• A. The strain that is resistant to all antibiotics
• B. The strain that produces heat-labile and heat-stable enterotoxins
• C. The strain that can ferment lactose
• D. The strain that does not cause diarrhea

Answer: (B)

Enterotoxigenic E. coli (ETEC) is specifically characterized by its ability to produce two types of enterotoxins: heat-labile (LT) and heat-stable (ST) toxins. These toxins play a crucial role in the pathogenesis of ETEC, leading to the development of diarrhea, particularly in travelers and young children in developing countries. The heat-labile toxin activates adenylate cyclase, increasing intracellular cAMP levels, while the heat-stable toxin stimulates guanylate cyclase, raising intracellular cGMP levels. This disruption of normal intestinal fluid balance results in diarrhea. The other options do not define ETEC accurately. Resistance to all antibiotics does not characterize any specific E. coli strain, as resistance patterns can vary widely. Fermentation of lactose is more indicative of other E. coli strains, particularly those that are lactose-fermenting, and does not alone specify ETEC. Lastly, ETEC is indeed associated with causing diarrhea, which contradicts the claim made in the final option. Thus, the defining feature that links ETEC to its pathogenic behavior is its production of both heat-labile and heat-stable enterotoxins.

Enterotoxigenic E. coli (ETEC) is specifically characterized by its ability to produce two types of enterotoxins: heat-labile (LT) and heat-stable (ST) toxins. These toxins play a crucial role in the pathogenesis of ETEC, leading to the development of diarrhea, particularly in travelers and young children in developing countries. The heat-labile toxin activates adenylate cyclase, increasing intracellular cAMP levels, while the heat-stable toxin stimulates guanylate cyclase, raising intracellular cGMP levels. This disruption of normal intestinal fluid balance results in diarrhea.

The other options do not define ETEC accurately. Resistance to all antibiotics does not characterize any specific E. coli strain, as resistance patterns can vary widely. Fermentation of lactose is more indicative of other E. coli strains, particularly those that are lactose-fermenting, and does not alone specify ETEC. Lastly, ETEC is indeed associated with causing diarrhea, which contradicts the claim made in the final option. Thus, the defining feature that links ETEC to its pathogenic behavior is its production of both heat-labile and heat-stable enterotoxins.