What is tolerance to a medicine?
Drug tolerance occurs when any antibiotic is given so readily for any sign of infection, even if it is not really necessary.
The microbes develop tolerance to it and don't get killed. It is always advisable to go to a doctor to prescribe any medicine especially for any sign of infection. If after his prescription of a particular antibiotic, there is no sign improvement, then he'll order culture and sensitivity( blood work) and see which antibiotic will be effective against a particular microorganism.