Acquisition and Loss of CTX-M-Producing and Non-Producing Escherichia coli in the Fecal Microbiome of Travelers to South Asia

Abstract

Escherichia coli strains which produce CTX-M extended-spectrum beta-lactamases are endemic as colonizers of humans and in the environment in South Asia. This study demonstrates that acquisition of CTX-M-producing E. coli (CTX-M-EC) in travelers from the United Kingdom to South Asia is polyclonal, which is likely due to multiple acquisition events from contaminated food and drinking water during travel. CTX-M-EC frequently persists in the fecal microbiome for at least 1 year after acquisition, often alongside newly acquired non-CTX-M E. coli strains. In travelers who acquire CTX-M-EC, pre-travel non-CTX-M E. coli remains as a minority population in the gut until the CTX-M-EC strains are lost. The non-CTX-M strains are then reestablished as the predominant E. coli population. This study has shed light on the dynamics of CTX-M-EC acquisition, colonization, and loss after travel. Future work involving manipulation of nonvirulent resident E. coli could be used to prevent colonization with antibiotic-resistant E. coli.

Real-time sampling of travelers shows intestinal colonization by multidrug-resistant bacteria to be a dynamic process with multiple transient acquisitions

“…Over the duration of their visits, the volunteers were colonized by up to five different strains, and often acquired multiple ESBL-GN species. Few traveler studies have employed genome-level analyses [18], but several have reported isolating more than one new colonizing ESBL-GN strain from posttravel samples [10][11][12][13][14]. Our data reveal the true scale and complexity at which drug-resistant bacteria colonize the intestinal tract during travel, demonstrating that it has been seriously underestimated.…”

“…Colonization occurs even during short visits [8][9][10][11][12][13][14][15] and without antimicrobial use [17] and can last for months or even over a year [8,12,13] and lead to further spread after return home [8,13]. Genome-level analysis of MDR strains colonizing travelers shows that newly acquired MDR strains tend to displace resident intestinal commensal E. coli strains alongside new non-MDR strains, such that the pre-travel population remains as a minority [18].…”

Antimicrobial resistance associations with national primary care antibiotic stewardship policy: Primary care-based, multilevel analytic study

“…The explanation for this is not clear. The ecological fallacy could be operating as described above, or given people can become persistently colonised with resistant E. coli following a short stay in a different environment, for example during overseas travel or hospitalisation, [32,33] another possibility is that co-amoxiclav and cefalexin resistance in the community is linked to use of these or related drugs in other settings, such as secondary care. In a 2017/18 survey of 900 cefalexin resistant urinary E. coli isolates from primary care in the same study area, 626 (69.6%) were found to be resistant to third generation cephalosporins used in secondary care, of which 571 (91.2%) produced the extended spectrum beta-…”

Large-scale genome analysis of bovine commensal Escherichia coli reveals that bovine-adapted E. coli lineages are serving as evolutionary sources of the emergence of human intestinal pathogenic strains

“…It has also been reported that phylogroup B2 or D strains predominated (>70%) in the E. coli strains isolated from biopsy samples of human lower intestinal tracts in Australia (Gordon et al 2015). However, in a recent analysis of E. coli strains isolated from healthy individuals who traveled from the United Kingdom to South Asia (Bevan et al 2018), not only phylogroups B2 and D strains but also phylogroup A strains were predominant. In another recent study that analyzed E. coli isolates from Tanzanian children under the age of 5, phylogroups A and B1 strains were most frequently isolated (Richter et al 2018).…”