Dynamics of resistance plasmids in extended spectrum {beta}-lactamase-producing Enterobacteriaceae during post-infection colonization [Epidemiology and Surveillance]

Extended spectrum β-lactamase-producing Enterobacteriaceae (EPE) are a major cause of bloodstream infections and the colonization rate of EPE in the gut microbiota of individuals lacking prior hospitalization or comorbidities is increasing. In this study we performed an in-depth investigation of the temporal dynamics of EPE and their plasmids during one year by collecting fecal samples from three patients initially seeking medical care for urinary tract infections. In two of the patients the same strain that caused the UTI was found at all consecutive samplings from the gut microbiota and no other EPEs were detected, while in the third patient the UTI strain was only found in the initial UTI sample. Instead, this patient presented a complex situation where a mixed microbiota of different EPE strain types, including three different E. coli ST131 variants, as well as different bacterial species was identified over the course of the study. Different plasmid dynamics were displayed in each of the patients including spread of plasmids between different strain types over time, transposition of bla_CTX-M-15 from the chromosome to a plasmid followed by subsequent loss through homologous recombination. Small cryptic plasmids were found in all isolates from all patients and they appear to move frequently between different strains in the microbiota. In conclusion, we could demonstrate an extensive variation of EPE strain types, plasmid composition, rearrangements and horizontal gene transfer of genetic material illustrating the high dynamics nature and interactive environment of the gut microbiota during post UTI carriage.

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