Can a New Antibiotic Safely Prevent Travelers' Diarrhea? FREE

Travelers to developing countries often develop diarrhea, which is usually caused by consuming food or water contaminated with bacteria. Daily antibiotics can prevent travelers' diarrhea but have many adverse effects, such as making bacteria in the body more resistant to antibiotics. Therefore, the risk of taking daily antibiotics to prevent travelers' diarrhea is usually considered greater than the benefit. Rifaximin, an antibiotic used in other countries to treat diarrhea, recently became available in the United States. Rifaximin is an effective treatment for travelers' diarrhea once it has developed and might also be useful for preventing travelers' diarrhea.

To see if rifaximin is safe and effective when taken to prevent travelers' diarrhea.

210 students from the United States who were attending classes in Guadalajara, Mexico. The students were at risk for travelers' diarrhea because they lived with local families. All were older than age 18 years and were generally healthy.

The researchers randomly assigned the students to take rifaximin or placebo for 2 weeks after their arrival in Mexico. They asked the students to keep a diary of symptoms and then compared how many people developed diarrhea or adverse drug effects. They also checked to see if the antibiotic led to changes in the kinds of normal bacteria that live in the gut and in the antibiotic resistance of those bacteria.

Approximately 15% of students who took rifaximin and more than 50% of the students who took placebo developed diarrhea. Side effects were similar in all groups. No important changes in the type of gut bacteria or the antibiotic resistance of those bacteria were detected in students taking the antibiotic.

The study findings may not apply to areas where travelers' diarrhea is caused by bacteria different from those in Mexico. They also do not apply to travelers' diarrhea caused by viruses, against which antibiotics have no effect. The study duration was 4 to 5 weeks. Findings might differ over longer time periods.

Rifaximin appears to prevent travelers' diarrhea in Mexico when taken daily for 2 weeks. It is not a substitute for careful selection and preparation of food and water to avoid infection.