Why do antiobotic resistance occure? why do they become immune to the treating medicine.

Antibiotic resistanc: There are resistant microbes isolated in areas in which antibiotics have never been used. When we overuse antibiotics we select out these organisms and mutations occur that favor those bacteria best capable of surviving in a given environment.

Bacteria evolve!: Bacteria multiply rapidly and are able to adapt to various environments, conditions and chemical agents. They do this by a gene that undergoes mutations and variations. Through gene mutation, the surviving bacteria produce an agent, usually an enzyme that destroys the antibiotic molecule. This is just one of many ways that bacteria become resistant. Each exposure gives them another chance.