E-Coli: The Culprit of Childhood Diarrhea

Enterotoxigenic Escherichia coli (ETEC) bacteria are responsible for causing the highest number of recorded cases of childhood diarrhea in the developing world and are the most common cause of traveler’s diarrhea, as per the World Health Organization.

While in healthy adults this is merely an unpleasant inconvenience, in infants and young children this can lead to chronic malnutrition, stunted growth, and impaired cognitive function.

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‘Highest number of community-acquired cases of childhood diarrhea in the developing world is found to be caused by enterotoxigenic Escherichia coli (ETEC) bacteria, which is also the most common cause of traveler’s diarrhea.’

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ETEC uses long, thin filaments called ‘pili’ to attach to host intestinal epithelia, an early, vital step in diarrhea pathogenesis. These fibers are essential for the initiation of infection in the intestines by ETEC.

Leading Cause of Childhood and Traveler's Diarrhea

Now, researchers from Boston University Chobanian & Avedisian School of Medicine have found that pili are fine-tuned for their preferred microenvironments, such as the gut or the urinary tract. They also found some use short loops to bind themselves to one another. Others use long extensions to stretch a long way.

This discovery has important implications for creating better therapeutics against diarrheal diseases.

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“Unwinding (and rewinding) of pili reduces the force at the site of binding and allows the bacteria to stay attached. Because pili are critical for bacteria to cause disease, finding a way to prevent pili from unwinding and rewinding can be used in the future to prevent diarrheal disease,” explained corresponding author Esther Bullitt, PhD, associate professor of physiology & biophysics.

The researchers used a combination of methods that included imaging the pili in a near-native state using a cryogenic electron microscope, using lasers to pull on the pili and measure the force it takes to unwind them, and computer simulations to watch the unwinding of the atomic level.

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Encopresis or paradoxical diarrhea is the leakage of stool and soiling clothes, mostly without one’s knowledge and is more common in children above four years but can affect adults also. The most common cause is constipation.

Because pili on different strains of bacteria are tuned for their environment, the researchers are looking for ways to specifically target disease-causing bacteria.

“Therapeutics that disrupt pili and allow bacteria to be washed away have advantages over current antibiotics, as physical removal would not lead to the evolution of resistant strains and only the pathogens would be targeted while leaving the ‘good’ bacteria of the microbiome intact,” said Bullitt.

These finds appear online in the journal Structure.

Source-Eurekalert