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Neomycin resistance is a drop in susceptibility to the antibiotic neomycin. This medication can be used in the treatment and prevention of some kinds of infections. It is also used in medical research, where selective use of neomycin resistance can be used to mark cell cultures. Study into how and why bacteria develop resistance to this and other antibiotics is important for medical care providers and researchers.
Bacteria have some unique tools for passing on resistance to antibiotics. They have specialized independent Deoxyribonucleic Acid (DNA) molecules known as plasmids which can reproduce separately of the organism’s DNA. When a bacterium replicates, it can pass on plasmids to the next generation, but the organisms can also swap them with each other. When the DNA carries a gene for drug resistance, it can spread quickly through a bacterial population via horizontal gene transfer.
Frequent exposure to antibiotics tends to promote the growth of organisms carrying partial or full resistance. Over time, this can result in the creation of a fully resistant strain that will not respond to a given antibiotic. Neomycin resistance commonly involves organisms that colonize the skin and gut.
In the practice of medicine, resistance to antibiotics can be a significant issue. If a patient with a resistant infection receives the wrong antibiotic, the drug won’t kill the bacteria, potentially allowing the infection to get much worse. Some organisms may carry resistance genes for multiple drugs, which can complicate medical treatment. For this reason, antibiotics are used with care in medical practice, particularly in the case of neomycin, which can also damage the liver and kidneys and thus is not a medication of first choice.
Researchers can use plasmids carrying neomycin resistance to their advantage. When working with cells in culture, they attach a plasmid to the genes they are studying. Their goal is to insert the gene into the cells in a process called transfection. The cells can be grown to allow them to start expressing the gene, and then treated with neomycin. Cells that weren’t transfected will die, while the others will survive, creating a pure and stable cell line.
In some scientific labs, it may be more efficient to order from a scientific supply company, in which case the supplier develops DNA for transfection and sends it to the lab. Others may handle their own processing, allowing researchers to customize genes and markers for specific studies. Neomycin resistance is one among many tools that can be used to tag a cell line for research purposes.