Not sure if there is an auto-fix...that just appears to be sloppy coding.
You can fix it with a couple quick regex search/replace in Calibre Editor:
Code:
1) change the italic
search: <span class="c_current__and__white_background__and__italic">(.*?)</span>
replace: <em>\1</em>
2) remove the other
search: <span class="c_current__and__white_background1">(.*?)</span>
replace: \1