A bacterial infection can eventually go away on it's own without antibiotics but it can take from 10 to 14 days and sometimes even a month before the bacterial infection will go away on it's own.
If you take antibiotics the bacterial infection will go away much sooner and the bacterial infection should be gone within 2 to 3 days with antibiotics.
If you're pregnant you should take pills for the bacterial infection to help it go away to prevent any harm for the unborn baby.