Antibiotic resistant bacteria develop when bacteria are exposed to antibiotics. Bacteria can share antibiotic resistance genes with other bacteria through horizontal gene transfer. Bacteria can also develop resistance genes through natural selection and mutation. Antibiotic resistance genes can be inherited by future generations of bacteria. The use of antibiotics in agriculture and the environment can also contribute to the development of antibiotic resistance. 

Antibiotic resistant bacteria are a significant concern in modern medicine, as they pose a serious threat to the effective treatment of bacterial infections. These bacteria are able to survive and grow despite the presence of antibiotics, making it difficult to eradicate them, and increasing the risk of developing superbugs that are resistant to all available treatments.

So, what causes antibiotic resistant bacteria to develop?

1. Exposure to Antibiotics: Antibiotic resistant bacteria develop when bacteria are exposed to antibiotics. These drugs are designed to kill or inhibit the growth of bacteria, but bacteria are capable of developing resistance to antibiotics over time. When antibiotics are used to treat an infection, some bacteria may survive and reproduce, passing along genetic material that confers resistance to the drug. This is particularly common when antibiotics are used at sub-therapeutic doses, or when they are prescribed for inappropriate reasons.

2. Horizontal Gene Transfer: Bacteria can share antibiotic resistance genes with other bacteria through horizontal gene transfer. This occurs when a piece of genetic material, such as a plasmid or phage, transfers antibiotic resistance genes from one bacterium to another. This can happen during bacterial conjugation, transformation, or transduction. Horizontal gene transfer can occur between different species of bacteria, making it difficult to control the spread of antibiotic resistance.

3. Natural Selection and Mutation: Bacteria can also develop resistance genes through natural selection and mutation. When exposed to antibiotics, some bacteria may mutate or acquire mutations that allow them to survive and reproduce, while others may be eliminated. Over time, the survivors may pass on these mutations to future generations, and the population of resistant bacteria may grow. Additionally, natural selection can favor bacteria that are better adapted to surviving in the presence of antibiotics, leading to the development of resistant strains.

4. Inheritance: Antibiotic resistance genes can be inherited by future generations of bacteria. When a resistant bacterium reproduces, it passes on its resistance genes to its offspring. This can happen through the process of vertical gene transfer, where resistance genes are passed down from parent to offspring during bacterial reproduction. This means that bacteria with resistance genes can spread and persist in the environment, even in the absence of antibiotics.

5. Agricultural and Environmental Use: The use of antibiotics in agriculture and the environment can also contribute to the development of antibiotic resistance. Bacteria on livestock, poultry, and farm animals can be exposed to antibiotics through the feed or the water they consume. These antibiotics may then pass through the food chain, leading to antibiotic residues in meat and milk. Furthermore, antibiotics can also be present in wastewater, sewage, and soil, which may lead to the spread of resistant bacteria in the environment. This can create opportunities for resistant bacteria to exchange antibiotic resistance genes with other bacteria, and increase their likelihood of spreading to humans.

In conclusion, antibiotic resistant bacteria develop through various mechanisms, including exposure to antibiotics, horizontal gene transfer, natural selection and mutation, inheritance, and the use of antibiotics in agriculture and the environment. It is essential to monitor and control the use of antibiotics, and to implement measures to prevent the spread of antibiotic resistance, in order to ensure effective treatment of bacterial infections and maintain public health.