Resistance
A term used to describe bacteria which have mutated or changed so they are not affected by an antibiotic that previously killed them or slowed their growth. As more bacteria become resistant to various antibiotics, there are fewer antibiotics which will have an affect on them, thus newer and stronger antibiotics will need to be developed. Inappropriate use of antibiotics (using them too often, for too short a duration or in insufficient dose) may promote the development of resistance.