Antibiotic use by travelers may add to global spread of superbugs
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, according to a new study published in Clinical Infectious Diseases and now available online. The study authors call for greater caution in using antibiotics for travelers’ diarrhea, except in severe cases, as part of broader efforts to fight the growing public health crisis of antibiotic resistance and the spread of highly resistant bacteria worldwide.
“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.
In the study, researchers collected stool samples for testing from 430 Finns before and after they travelled outside of Scandinavia. The goal: Determine if their guts became colonized by a resistant type of bacteria from the Enterobacteriaceae family that produces a key enzyme, extended-spectrum beta-lactamase (ESBL), which confers resistance to many commonly used antibiotics. The researchers looked for risk factors in the travelers’ behavior that may have facilitated colonization by these resistant bacteria. The U.S. Centers for Disease Control and Prevention has called ESBL-producing bacteria a serious concern and a significant threat to public health. The bacteria can cause severe infections that are harder and more expensive to treat and more likely to be fatal.
The Finnish travelers completed surveys about their trips, including questions about diarrhea and antibiotic use, which can disrupt the gut’s balanced ecosystem, sometimes allowing resistant bacteria to become incorporated into the intestinal ecosystem.
Overall, 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. Among those who took antibiotics for diarrhea, 37 percent were colonized. Those travelling to South Asia faced the highest risk of contracting the resistant bacteria: 80 percent of travelers who took antibiotics for diarrhea while visiting the region were colonized with ESBL bacteria. Southeast Asia, East Asia, and North Africa together with the Middle East, in order, were next highest in risk.
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. Had the number of colonized travelers been slightly larger, Dr. Kantele noted, symptomatic infections would probably have been detected.
“More than 300 million people visit these high-risk regions every year,” Dr. Kantele said. “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.”
Greater attention should be aimed at educating international travelers to take a more cautious attitude toward antibiotics, the study authors wrote. 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.
How to Keep Antibiotics From Causing Diarrhea
Antibiotics are commonly prescribed to fight bacterial infections, but after four or five days taking the medication, you might experience diarrhea, an antibiotics side effect. Antibiotics work by destroying bacteria that are making you ill, but they also kill good, or helpful, bacteria in your intestinal system. This disrupts the delicate balance in your intestines, allowing bad intestinal bacteria that are resistant to the antibiotic to increase. “You’re upsetting the normal fecal flora [microorganisms], and that can lead to diarrhea,” says Henry Parkman, MD, a gastroenterologist and professor of medicine in the gastroenterology section at Temple University School of Medicine in Philadelphia.
Antibiotics and Diarrhea: Understanding the Reaction
Any antibiotic can cause you to have diarrhea, whether taken orally or by injection, but broad-spectrum antibiotics - antibiotics that kill a wide range of bacteria - are the most likely to affect you. These include clindamycin (Cleocin), certain types of penicillins, and cephalosporins.
Most of the time, diarrhea as an antibiotics side effect is mild and will stop on its own or when you stop taking your medicine. However, “antibiotic-associated diarrhea is also seen a lot in patients who are hospitalized or in nursing homes,” says Dr. Parkman. And then it can be more serious. In some elderly or ill patients, diarrhea can lead to serious complications such as dehydration, a perforated colon (hole in the colon wall), or toxic megacolon, in which the colon becomes distended and could rupture.
Protecting Yourself
Some patients find they can take certain antibiotics and diarrhea won’t be a problem, but taking other drugs will cause diarrhea, Parkman says. If you have diarrhea from taking antibiotics, especially if symptoms persist or worsen, call your doctor. If it’s necessary for you to continue antibiotics treatment, your doctor may be able to switch you to another drug that won’t have this side effect.
If you’re taking an antibiotic, consider changing your diet for a few days to avoid foods that commonly trigger diarrhea, such as dairy products, fatty foods, spicy foods, and foods high in fiber like whole-grain breads, cereals, and beans. You should also drink extra water and skip caffeine and alcohol. If your symptoms of antibiotic-associated diarrhea are severe, your doctor may recommend bed rest, intravenous fluids to replace your electrolytes - sodium, potassium and chloride - and another antibiotic to treat the bad intestinal bacteria that is causing diarrhea.
In a related editorial, Bradley A. Connor, MD, of Weill Cornell Medical College, and Jay S. Keystone, MD, of Toronto General Hospital, noted that the study provides compelling evidence that antibiotic use increases a traveler’s risk of colonization by ESBL-producing bacteria. Additional research is needed on what criteria should guide travelers’ use of antibiotics for severe diarrhea, the effect of travel on the gut microbiome, and new preventive measures travelers can use to avoid diarrhea, the editorial authors noted.
Fast Facts
Researchers found that taking antibiotics for travelers’ diarrhea increased the risk of becoming colonized by extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae, a concerning type of drug-resistant superbug that is a serious threat to public health.
Travelers who return home with ESBL-producing bacteria in their gut may unknowingly spread these superbugs to their own home countries, even if they do not develop infections themselves.
Developing regions posed the highest risk, led by South Asia, where 80 percent of the travelers who took antibiotics for diarrhea while visiting the region were colonized with ESBL-producing bacteria.
Travelers’ diarrhea is the single most common cause of illness during international travel. Most cases resolve on their own, without treatment.
More information on travelers’ diarrhea, including tips for prevention, is available from the U.S. Centers for Disease Control and Prevention: http://wwwnc.cdc.gov/travel/page/travelers-diarrhea
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Editor’s note: The study authors’ affiliations, acknowledgments, and disclosures of financial support and potential conflicts of interests are available in the article. The article and editorial are embargoed until 12:01 a.m. EST on Thursday, Jan. 22. These pre-publication links are for media access only:
Antibiotic Self-treatment of Travelers’ Diarrhea: Helpful or Harmful?
Clinical Infectious Diseases is a leading journal in the field of infectious disease with a broad international readership. The journal publishes articles on a variety of subjects of interest to practitioners and researchers. Topics range from clinical descriptions of infections, public health, microbiology, and immunology to the prevention of infection, the evaluation of current and novel treatments, and the promotion of optimal practices for diagnosis and treatment. The journal publishes original research, editorial commentaries, review articles, and practice guidelines and is among the most highly cited journals in the field of infectious diseases. Clinical Infectious Diseases is an official publication of the Infectious Diseases Society of America (IDSA). Based in Arlington, Va., IDSA is a professional society representing nearly 10,000 physicians and scientists who specialize in infectious diseases.
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