Case insensitive preg_match and replacement of found?

Question

PHP

I find unnecessary words, but I can’t change ....
I understand that the design "/$item/iu"is not correct, but it $itemalso doesn’t work

foreach($slova as $item)
 {
    if (preg_match("/$item/iu",$opis)) 
    { 
       $opis = str_replace("/$item/iu", "", $opis); 
    }
 }

Answer 1

Why did preg_replace or preg_replace_callback fail? And it would be nice to run variables through preg_quote