class Config
{
    private $usuario;
    private $senha;
    private $_connection;

    public function __construct($bd)
    {
        switch($bd)
        {
        	case DBI:
        		$this->$campus = 'mantenedora';
        		$this->$site = 'teste';
        		include 'phpdbi.inc';
        		break;

        	case MANTENEDORA:
        		$this->usuario = 'l_teste';
        		$this->senha = 'teste12345';
        		$this->_connection = "teste";
        		break;

        	default:
        		break;
        }
    }

    public function getUsuario()
    {
        return $this->usuario;
    }
    public function getSenha()
    {
        return $this->senha;
    }
    public function getConnection()
    {
        return $this->_connection;
    }
}

	$config = new Config($bd);

        $this->usuario = $config->getUsuario();
        $this->senha = $config->getSenha();
        $this->_connection = $config->getConnection();

    	$this->conectarBanco();