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 .