Abstract
Enterotoxigenic Escherichia coli (ETEC) is the primary aetiologic agent of traveller’s diarrhoea and a significant cause of diarrhoeal disease and death in developing countries. ETEC O169:H41 strains are known to cause both traveller’s diarrhoea and foodborne outbreaks in developed countries and are cause for concern. Here, whole-genome sequencing (WGS) was used to assemble 46 O169:H41 (ST182) E. coli draft genomes derived from two airplane waste samples sourced from a German international airport. The ST182 genomes were compared with all 84 publicly available, geographically diverse ST182 genomes to construct a core genome-based phylogenetic tree. ST182 isolates were all phylogroup E, the majority serotype O169:H41 (n = 121, 93%) and formed five major clades. The airplane waste isolates differed by an average of 15 core SNPs (range 0–45) but their accessory genome content was diverse. While uncommon in other ST182 genomes, all airplane-derived ST182 isolates carried: (i) extended-spectrum β-lactamase gene blaCTX–M–15 notably lacking the typical adjacent ISEcp1; (ii) qnrS1 and the S83L mutation in gyrA, both conferring resistance to fluoroquinolones; and (iii) a class 1 integron structure (IS26-intI1Δ648-dfrA17-aadA5-qacEΔ1-sul1-ORF-srpC-padR-IS6100-mphR-mrx-mphA-IS26) identified previously in major extraintestinal pathogenic E. coli STs but not in ETEC. ST182 isolates carried ETEC-specific virulence factors STp + CS6. Adhesin/invasin tia was identified in 89% of aircraft ST182 isolates (vs 23%) and was located on a putative genomic island within a hotspot region for various insertions including PAI I536 and plasmid-associated transposons. The most common plasmid replicons in this collection were IncFII (100%; F2:A-:B-) and IncB/O/K/Z (89%). Our data suggest that potentially through travel, E. coli ST182 are evolving a multidrug-resistant profile through the acquisition of class 1 integrons and different plasmids.
Highlights
Throughout history, travel has played a key role in disseminating infectious diseases and with air travel servicing over four billion passengers annually (ICAO, 2018), travellers in unprecedented numbers and speeds continue to shape the emergence and spread of disease to ever broader geographic locations (Institute of Medicine Forum on Microbial Threats, 2010)
Enterotoxigenic Escherichia coli (ETEC) O169:H41 strains have caused at least 29 outbreaks of gastroenteritis in developed countries, yet to date, no comparative genomic analyses nor reports on antimicrobial resistance (AMR) pertaining to this ETEC serotype have been published
We present 46 draft genomes of O169:H41 (ST182) E. coli isolates originating from sewage taken from aircraft landing at an international airport in Germany on a single day in 2016
Summary
Throughout history, travel has played a key role in disseminating infectious diseases and with air travel servicing over four billion passengers annually (ICAO, 2018), travellers in unprecedented numbers and speeds continue to shape the emergence and spread of disease to ever broader geographic locations (Institute of Medicine Forum on Microbial Threats, 2010). Another study found that 80% of travellers returning from southern Asia that used antimicrobials to treat diarrhoea whilst abroad had subsequently acquired ESBL-producing Enterobacteriaceae, as opposed to 47% of travellers that experienced diarrhoea without antimicrobial treatment, and 23% of travellers that reported neither diarrhoea nor antimicrobial use (Kantele et al, 2015). Another recent study involving real-time colonisation dynamics indicated that 70% of participant travellers returning from southeast Asia were colonised with ESBL-producing Enterobacteriaceae but that all had acquired ESBL-producing Enterobacteriaceae at one point in their travels (Kantele et al, 2021). Airplane sewage has been found to be an extraordinary source of antimicrobial resistance genes (ARGs), including ESBL genes, such as blaCTX-M (Heß et al, 2019)
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