You want a charger that inputs 110V-240V AC and outputs 5V DC up to 2.0A to a USB female port, plus a male USB to male mini-USB cable. Avoid chargers that are designed for Apple iPhones, as they output 2.1A to Apple devices, but only 0.5A to non-Apple devices.
If your charger inputs 110V-240V AC, then all you'll need for Italy is the appropriate 2 or 3 round prong male adapter plug with a female US socket on the back. If you can only find a 110V-120V AC charger for US use, buy it, and get a step-down converter to input European 220V-240V AC and output 110V-120V AC.