title: Polyclonal Intestinal Colonization with Extended-Spectrum Cephalosporin-Resistant Enterobacteriaceae upon Traveling to India.
abstract: We aimed to assess the intestinal colonization dynamics by multiple extended-spectrum cephalosporin-resistant Enterobacteriaceae (ESC-R-Ent) clones in Swiss travelers to India, a country with high prevalence of these multidrug-resistant pathogens. Fifteen healthy volunteers (HVs) colonized with ESC-R-Ent after traveling to India who provided stools before, after, and at 3- and 6-month follow-up are presented in this study. Stools were enriched in a LB broth containing 3 mg/L cefuroxime and plated in standard selective media (BLSE, ChromID ESBL, Supercarba) to detect carbapenem- and/or ESC-R-Ent. At least 5 Enterobacteriaceae colonies were analyzed for each stool provided. All strains underwent phenotypic tests (MICs in microdilution) and molecular typing to define bla genes (microarray, PCR/sequencing), clonality (MLST, rep-PCR), and plasmid content. While only three HVs were colonized before the trip, all participants had positive stools after returning, but the colonization rate decreased during the follow-up period (i.e., six HVs were still colonized at both 3 and 6 months). More importantly, polyclonal acquisition (median of 2 clones, range 1-5) was identified at return in all HVs. The majority of the Escherichia coli isolates belonged to phylogenetic groups A and B1 and to high diverse non-epidemic sequence types (STs); however, 15% of them belonged to clonal complex 10 and mainly possessed bla CTX-M-15 genes. F family plasmids were constantly found (~80%) in the recovered ESC-R-Ent. Our results indicate a possible polyclonal acquisition of the ESC-R-Ent via food-chain and/or through an environmental exposure. For some HVs, prolonged colonization in the follow-up period was observed due to clonal persistence or presence of the same plasmid replicon types in a new bacterial host. Travel medicine practitioners, clinicians, and clinical microbiologists who are facing the returning travelers and their samples for different reasons should be aware of this important phenomenon, so that better infection control measures, treatment strategies, and diagnostic tests can be adopted.
authors.affiliation: Institute for Infectious Diseases, University of BernBern, Switzerland; Graduate School of Cellular and Biomedical Sciences, University of BernBern, Switzerland.
authors.forename: João
authors.initials: J
authors.lastname: Pires
authors.affiliation: Division for Infectious Diseases and Hospital Epidemiology, University Hospital BaselBasel, Switzerland; Swiss Tropical and Public Health InstituteBasel, Switzerland; Epidemiology, Biostatistics and Prevention Institute, University of ZurichZurich, Switzerland.
authors.forename: Esther
authors.initials: E
authors.lastname: Kuenzli
authors.affiliation: Institute for Infectious Diseases, University of Bern Bern, Switzerland.
authors.forename: Sara
authors.initials: S
authors.lastname: Kasraian
authors.affiliation: Institute for Infectious Diseases, University of Bern Bern, Switzerland.
authors.forename: Regula
authors.initials: R
authors.lastname: Tinguely
authors.affiliation: Department of Infectious Diseases, Bern University Hospital, University of Bern Bern, Switzerland.
authors.forename: Hansjakob
authors.initials: H
authors.lastname: Furrer
authors.affiliation: Institute for Infectious Diseases, University of BernBern, Switzerland; Department of Infectious Diseases, Bern University Hospital, University of BernBern, Switzerland.
authors.forename: Markus
authors.initials: M
authors.lastname: Hilty
authors.affiliation: Swiss Tropical and Public Health InstituteBasel, Switzerland; Epidemiology, Biostatistics and Prevention Institute, University of ZurichZurich, Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Hatz
authors.affiliation: Institute for Infectious Diseases, University of Bern Bern, Switzerland.
authors.forename: Andrea
authors.initials: A
authors.lastname: Endimiani
keywords: CTX-M; E. coli; ESBL; environment; food-chain; pAmpC; plasmid; travelers