Taking antibiotics for diarrhea may put travelers visiting developing parts of the world at higher risk for contracting superbugs and spreading these daunting drug-resistant bacteria to their home countries.
"The great majority of all cases of travelers' diarrhea are mild and resolve on their own," said lead study author Anu Kantele, MD, PhD, associate professor in infectious diseases at Helsinki University Hospital in Finland.
Researchers collected stool samples from 430 Finns before and after they travelled outside of Scandinavia. The goal was to determine if a resistant type of bacteria from the Enterobacteriaceae family colonized their guts. It produces resistance to many antibiotics by producing a key enzyme, extended-spectrum beta-lactamase (ESBL).
The U.S. Centers for Disease Control and Prevention has called ESBL-producing bacteria a serious concern and a significant threat to public health.
21 percent of the travelers to tropical and subtropical areas in the study had unknowingly contracted ESBL-producing bacteria during their trips.
Significant risk factors for colonization were travelers' diarrhea and treating it with antibiotics while abroad. Southeast Asia, East Asia, and North Africa together with the Middle East, in order, were next highest in risk.
80 percent of travelers who took antibiotics for diarrhea while visiting the region were colonized with ESBL bacteria. Those travelling to South Asia faced the highest risk of contracting the resistant bacteria.
Even if colonized travellers do not develop infections themselves, they may, after returning home, unknowingly spread the superbugs to their own developed countries, where today these bacteria are less prevalent.
A laboratory survey showed that none of the 90 colonized travelers in the study developed infections caused by the resistant bacteria during the next year.
Dr. Kantele said, "More than 300 million people visit these high-risk regions every year. If approximately 20 percent of them are colonized with the bugs, these are really huge numbers. This is a serious thing. The only positive thing is that the colonization is usually transient, lasting for around half a year."
In general, Dr. Kantele said, travelers with diarrhea should drink plenty of fluids to avoid dehydration, use non-antibiotic antidiarrheal drugs available over the counter to help relieve symptoms if needed, and seek medical attention for severe cases, such as those with high fever, bloody stools, or serious dehydration.