Can a baby get sick from a dirty bottle?

Yes, they can get sick as a result of a dirty bottle. You see, dirty bottles are a source of bacteria. The bacteria in the bottle goes down into the immune system of the baby, and attacks the central nervous system. If a baby consumes this source of bacteria it won't always affect the baby. If after drinking from a dirty bottle, the baby vomits regulary

or it starts swelling or gets nosebleeds that are irregular or even vomits blood , take it to your GP or A&E

because it may have an urgent medical problem or might even be in risk of its life. So get it checked out !