Fitness costs of various mobile genetic elements in Enterococcus faecium and Enterococcus faecalis

Abstract

ObjectivesTo determine the fitness effects of various mobile genetic elements (MGEs) in Enterococcus faecium and Enterococcus faecalis when newly acquired. We also tested the hypothesis that the biological cost of vancomycin resistance plasmids could be mitigated during continuous growth in the laboratory.MethodsDifferent MGEs, including two conjugative transposons (CTns) of the Tn916 family (18 and 33 kb), a pathogenicity island (PAI) of 200 kb and vancomycin-resistance (vanA) plasmids (80–200 kb) of various origins and classes, were transferred into common ancestral E. faecium and E. faecalis strains by conjugation assays and experimentally evolved (vanA plasmids only). Transconjugants were characterized by PFGE, S1 nuclease assays and Southern blotting hybridization analyses. Single specific primer PCR was performed to determine the target sites for the insertion of the CTns. The fitness costs of various MGEs in E. faecium and E. faecalis were estimated in head-to-head competition experiments, and evolved populations were generated in serial transfer assays.ResultsThe biological cost of a newly acquired PAI and two CTns were both host- and insertion-locus-dependent. Newly acquired vanA plasmids may severely reduce host fitness (25%–27%), but these costs were rapidly mitigated after only 400 generations of continuous growth in the absence of antibiotic selection.ConclusionsNewly acquired MGEs may impose an immediate biological cost in E. faecium. However, as demonstrated for vanA plasmids, the initial costs of MGE carriage may be mitigated during growth and beneficial plasmid–host association can rapidly emerge.

The genetic basis of the fitness costs of antimicrobial resistance: a meta‐analysis approach

“…; Starikova et al. ). This host‐plasmid coevolution could also explain why the cost of the same plasmid is so variable between different bacterial hosts – hosts in which a plasmid has a low fitness cost may have had a longer or more recent history of carrying that type of plasmid.…”

“…; Starikova et al. ). There are also costs of MGE acquisitions where the genetic background was not controlled (e.g.…”

Decreased Fitness and Virulence in ST10 Escherichia coli Harboring blaNDM-5 and mcr-1 against a ST4981 Strain with blaNDM-5

“…Although a considerable reduction in fitness was observed by newly acquired plasmids and other mobile genetic elements (Starikova et al, 2013; Göttig et al, 2016), some studies showed that carbapenemase-encoding plasmids contributed to low to moderate fitness cost to host (Schaufler et al, 2016; Di Luca et al, 2017). To explore whether bla NDM-5 or mcr-1 plasmid imposed a fitness cost on the host, the growth kinetics were investigated in the transconjugants.…”

Bruk av antibiotika hos barn i perioden 2005 – 16

“…Det er kunnskapshull knyttet til forståelsen av slike kostnader for bakteriene, og hvordan disse kan kvantifiseres og hvordan de påvirkes av kompensatoriske mutasjoner. Slik forståelse er nødvendig for å kunne forutsi i hvilken grad ervervet resistens er reversibel (Johnsen et al, 2009;Starikova et al, 2013;Starikova et al, 2012). Kunnskap om populasjonsstrukturen til mikrober er sentralt også med hensyn på forståelsen av mulige "utvaskingseffekter" hvor repetert tilførsel av konkurrerende bakteriepopulasjoner, f. eks som fôrtilskudd til husdyr, påvirker etablerte resistente populasjoner.…”