Resistance developed in bacteria is a natural biological phenomenon which is enhanced by a variety of factors including unnecessary use of antibiotics. When the bacteria are exposed to antibiotics continuously, they either adapt themselves for the antibiotic or die in a process termed as "Selective Pressure". The bacteria which are able to adapt themselves pass the genes for resistance and thus a group of antibiotic resistance bacteria is produced.

The consequences are severe. Hence, antibiotics ineffective in treating these resistant bacteria may cause severe and prolonged illness and produce life threatening conditions.

There is research going on to develop drugs for these. But, one can also help in preventing the development of resistance in bacteria by limiting the use of antibiotics when it is required essentially. Also, if you are taking an antibiotic for a specified time to treat some infection, complete the course. It will reduce the chances of development of resistance in bacteria.