$re = '/([^;\r\n])(["]+)([^;\r\n])/';
$str = '"A"";1;200;345;"Apotheker ""Blue tongue"";"Apeldoorn";12;"ABCD12""
""B";2;232;312;"Cafe "Blue Oyster";"Rotterdam";33;"DCBA21""""';
$subst = "$1$3";
$result = preg_replace($re, $subst, $str);
echo "The result of the substitution is ".$result;
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php