How does bacteria become resistant to antibiotics?

Antibiotics work by poisoning molecules in bacteria. Most cases of medically significant antibiotic resistance are not due to mutations but to complex enzymes that inactivate the poison. Bacteria can either have inherited or acquire these enzymes form other bacteria. ( Bacteria can pick up genes from dead bacteria and by exchanging genes with other bacteria in their environment)

Some cases of resistance result from a mutation where the bacteria loses the molecules which the poison is suppose to attack. These mutated bacteria survive better than normal bacteria in the presence of the antibiotic poisons. However these mutated bacteria do not survive as well as normal bacteria outside of the presence of the antibiotics.

An example would be the blind fish of Death Valley. These fish live in total darkness in underground rivers. The sharp rocks in the underground caverns caused great damage to the fishes eyes. As a result the fish have mutated losing their eyes. Tough tissue has replaced the sensitive eye tissue. These fish do better than normal unmutated fish in the darkness but would be less successful in normal conditions.

Bacteria become resistant to antibiotics through several mechanisms, including:

1. Mutation: Bacteria can undergo mutations in their genetic material, leading to changes that make them resistant to antibiotics.

2. Horizontal gene transfer: Bacteria can acquire resistance genes from other bacteria through mechanisms such as conjugation, transformation, and transduction.

3. Overuse and misuse of antibiotics: Overuse or misuse of antibiotics can exert selective pressure on bacteria, favoring the survival and proliferation of resistant strains.

4. Inadequate dosage or duration of antibiotic treatment: Incomplete courses of antibiotic treatment can allow bacteria to survive and develop resistance.

5. Evolutionary adaptation: Bacteria have the ability to adapt and evolve rapidly, allowing them to develop resistance to antibiotics over time.