$re = '/\b([A-Z]{4}):[^\]\[\d]*(\d{1,5})\b/';
$str = '08:28:57,990 DEBUG [http-0.0.0.0-18080-33] [tester] [1522412937602-580613] [TestManager] ABCD: loaded 35 test accounts';
preg_match_all($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