Error - Connect to Mysql with PDO

Question

I’m trying to connect to a Mysql Database Remotely, through PDO + PHP. Mysql Database is managed by a team, I don’t have access to it. The Database was created and the tables were created. My user gave the appropriate permissions to the bank. However, when I try to connect to it via PHP + PDO it generates the error below:

Fatal error: Uncaught exception 'PDOException' with message 'SQLSTATE[HY000] [2005] Unknown MySQL server host 'xxx:3306' (2)' in xxx:8 Stack trace: #0 xxx(8): PDO->__construct('mysql:host=a1-o...', 'user', 'senha') #1 xxx: db_connect() #2 {main} thrown in xxx on line 8

We leave a tcpdump running in the Mysql environment and when we try to connect to the database via PHP, there is no package there. But close telnet on port 3306.

Data from Mysql connection

define('DB_HOST', 'xxx:3306');
define('DB_USER', 'xxx');
define('DB_PASS', 'xxxx');
define('DB_NAME', 'xxx');

    <?php

/**
 * Conecta com o MySQL usando PDO
 */
function db_connect()
{
    $PDO = new PDO('mysql:host=' . DB_HOST . ';dbname=' . DB_NAME . ';charset=utf8', DB_USER, DB_PASS);

    return $PDO;
}



?>

Someone could help me?