Dishwashers will not always heat to high enough temperatures to kill all bacteria. It is advised to sterilise the bottles after washing in the dishwasher. If you rely solely on the dishwasher, you will need to run a hot programme with a minimum water temperature of 80 degrees centigrade. The bottles need be filled with formula immediately since the dishwasher does not leave them completely sterile.
Sterilising the baby's bottles may seem pointless, when they are crawling on the floor and putting everything they find into their mouths, but the bacteria that tend to stick to milk curds can be very dangerous, more so than the bacteria they find on the floor.