Warning: This answer applies to PHP 5.3.5 and lower. Do not use it for PHP version 5.3.6 (released in March 2011) or later.
Compare with Palec’s answer here.
Use:
$pdo = new PDO(
'mysql:host=hostname;dbname=defaultDbName',
'username',
'password',
array(PDO::MYSQL_ATTR_INIT_COMMAND => "SET NAMES utf8")
);
It forces UTF-8 on the PDO connection. It worked for me.