After molecular testing, half of all travel-acquired extended-spectrum β-lactamase (ESBL)-producing Escherichia coli strains qualified as pathogens and despite most of these being classified as extraintestinal pathogenic or uropathogenic E coli, the most common manifestation was traveler’s diarrhea, according to data published in Clinical Infectious Diseases.

Roughly one-third of the 100 million annual travelers to the tropics acquire ESBL- producing Enterobacteriaceae, often with undefined clinical consequences. To investigate ESBL-producing Enterobacteriaceae cases during travel, researchers prospectively recorded symptoms suggesting Enterobacteriaceae infections in 430 Finnish travelers, 90 of whom acquired ESBL-producing Enterobacteriaceae abroad. Laboratory-confirmed infections were then surveyed 5 years before and after travel.

Of the 90 participants who were carriers of ESBL-producing Enterobacteriaceae, infection with this genus of bacteria manifested as travelers’ diarrhea or urinary tract infection (UTI) in 75 and 3 participants, respectively. A total of 96 ESBL-producing E coli isolates were found in carriers; 51% of carriers exhibited a molecular pathotype, including 13 diarrheagenic E coli pathotypes, of which 10 were enteroaggregative E coli, 2 were enteropathogenic E coli and 1 was enterotoxigenic E coli. Of the 13 pathotypes, 12 were associated with traveler’s diarrhea. Specific pathotypes also included 39 extraintestinal pathogenic/uropathogenic E coli, none of which were associated with UTI.

Of ESBL-producing Enterobacteriaceae, 3 were hybrids of extraintestinal pathogenic/uropathogenic E coli and enteroaggregative E coli, 2 were associated with diarrhea, and none with UTI. In 15 of the 90 subjects, potential ESBL-producing Enterobacteriaceae infections were detected and the 10-year medical survey identified 4 laboratory-confirmed infections among all 430 travelers. All 4 of these occurred in travelers who screened negative after returning home from their index journeys but had traveled abroad before their infection episodes.

The study author’s noted that they may have missed cases in which ESBL-producing diarrheagenic E coli caused traveler’s diarrhea but were no longer detected upon the participants’ return because travel-acquired ESBL-producing Enterobacteriaceae may disappear during travel. Also, because post-travel stools were collected soon after return, some non-severe cystitis and traveler’s diarrhea episodes may not have been captured.  

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The study authors concluded that “among travel-acquired ESBL-[producing Enterobacteriaceae] strains, the most frequent pathotype is [extraintestinal pathogenic/uropathogenic E coli], yet pathotype-consistent clinical manifestations are more common among hosts colonized by [diarrheagenic E coli] than [extraintestinal pathogenic/uropathogenic E coli] strains.” In addition to this, they also suggested that more travel-acquired ESBL-producing Enterobacteriaceae may cause infections than previously thought and that despite growing concern about increases in antimicrobial resistance among clinical isolates, many clinicians still overlook the potential risks asymptomatic intestinal colonization by ESBL-producing Enterobacteriaceae may pose to travelers.

Reference

Kantele A, Lääveri T, Mero S, et al. Despite predominance of uropathogenic/extraintestinal pathotypes among travel-acquired extended-spectrum β-lactamase-producing Escherichia coli, the most commonly associated clinical manifestation is travelers’ diarrhea [published online April 29 2019]. Clin Infect Dis. doi:10.1093/cid/ciz182

This article originally appeared on Infectious Disease Advisor