$re = '/[^,]+enst.18[^,]+/m';
$str = 'abc|frame|gtk|enst.15|pc|hg|,abc|framex|gtk2|enst.59|pxc|h5g|,abc|frbx|hgk4|enst.18|pif|homg|
';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
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