Travelers' Antibiotic Use May Foster Drug-Resistant Bacteria

Laurie Barclay, MD

January 28, 2015

Antimicrobial use for travelers' diarrhea (TD) increased the risk for colonization by extended-spectrum drug-resistant betalactamase-producing Enterobacteriaceae (ESBL-PE), according to the findings of a study published online January 21 in Clinical Infectious Diseases. The researchers therefore suggest that travelers be advised not to use antibiotics for mild to moderate TD.

"The great majority of all cases of [TD] are mild and resolve on their own," lead author Anu Kantele, MD, PhD, associate professor in infectious diseases at Helsinki University Hospital in Finland, said in a news release.

Many travelers to regions with poor hygiene become colonized by resistant intestinal bacteria such as ESBL-PE and may transmit these strains to personal contacts and to medical care settings when they return home. Mortality and healthcare costs are higher with drug-resistant organisms.

"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."

Despite the potential global health risks caused by increased antimicrobial resistance, no intervention has attempted to prevent colonization of travelers. The researchers collected stool samples from 430 Finns before and after travel outside Scandinavia and analyzed them for ESBL- and carbapenemase-producing Enterobacteriaceae. They also used questionnaires to ask participants about antimicrobial use and other risk factors.

ESBL-PE colonization occurred in 21% (90/430) of travelers overall, but none of the 430 participants had carbapenemase-producing Enterobacteriaceae colonization. The researchers adjusted for sex, age, geographic region of travel, journey length, TD, use of antimicrobials, alcohol use, meals with locals, meal sites, contact with local healthcare, and accommodation with locals. After these adjustments, multivariable analyses of questionnaire responses showed that independent risk factors for ESBL-PE were geographic region, occurrence of TD, age, and use of antimicrobial drugs for TD.

ESBL-PE colonization occurred in 11% of those without TD or antibiotic use, in 21% of those with TD without antibiotic use, and in 37% of those with TD treated with antibiotics.

Travel to South Asia had the highest rates of colonization, with a rate of 46% overall: 23% in those without TD or antibiotic use, 47% in those with TD without antibiotic use, and 80% in those with TD treated with antibiotics. Rates in Southeast Asia were 14%, 32%, and 69%, respectively; the next highest rates were in East Asia, North Africa, and the Middle East.

"In modern pre-travel counseling for those visiting high-risk regions, travelers should be advised against taking antibiotics for mild or moderate TD," the study authors conclude.

They recommend that those with TD drink plenty of fluids, use over-the- counter nonantibiotic antidiarrheal drugs for symptom relief, and seek medical attention for severe TD with high fever, bloody stools, and/or serious dehydration.

In an accompanying editorial, Bradley A. Connor, MD, from Weill Cornell Medical College in New York City, and Jay S. Keystone, MD, from Toronto General Hospital, Ontario, Canada, described these findings of increased risk for colonization by ESBL-producing bacteria in travelers receiving antibiotics as "compelling."

However, they recommend further study on criteria determining 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 Finnish Governmental Subsidy for Health Science Research and the Scandinavian Society for Antimicrobial Chemotherapy Foundation supported this study. The authors and editorialists have disclosed no relevant financial relationships.

Clin Infect Dis. Published online January 21, 2015. Article full text, Editorial extract

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