documentclass{article}

usepackage{csquotes}
DeclareQuoteStyle[meide]{danish}
  {itshapequotedblbase}
  {textquotedblleft}
  [0.05em]
  {normalfontguillemotright}
  {guillemotleft}
setquotestyle[meide]{danish}

newcommandellision{%
    textnormaltextelp{}%
}

begin{document}

enquote{abc abc abc textelp{} abc abc abc} % the [...] is in italics

enquote{abc abc abc ellision{} abc abc abc} % the [...] is followed by empty brackets

enquote{abc abc abc {textnormaltextelp{}} abc abc abc} % same


end{document}