Which Enterobacteriaceae can cause traveler's diarrhea?

• A. Klebsiella pneumoniae
• B. Salmonella typhi
• C. Escherichia coli
• D. Morganella morganii

Answer: (C)

Escherichia coli is a leading cause of traveler's diarrhea, particularly the enterotoxigenic strains (ETEC) that produce toxins leading to watery diarrhea. This bacterium is commonly found in contaminated food and water, which is why it is often associated with travel to areas with poor sanitation.

Infections caused by E. coli can result from consuming undercooked meat, unpasteurized milk, or vegetables that have been washed with contaminated water. The mechanism by which E. coli causes diarrhea involves the adherence to the intestinal lining and the production of enterotoxins, which disrupt the normal absorption of fluids and electrolytes.

Other members of the Enterobacteriaceae family listed may cause gastrointestinal illness, but they are not primarily associated with traveler's diarrhea in the same way E. coli is. For example, while Salmonella typhi can lead to typhoid fever—a serious systemic infection—it's not the typical cause of traveler's diarrhea. Klebsiella pneumoniae is mainly known for causing pneumonia and other infections rather than diarrhea. Morganella morganii, though capable of causing infections, is less commonly implicated in travel-related gastrointestinal issues. Hence, E. coli stands out as the primary pathogen associated with traveler's diarrhea.