Health officials view the rise of drug-resistant TB with particular alarm. Public health experts warn that without an international effort to find and treat drug-resistant cases, the new strains of bacteria will spread widely. Drug-resistant TB strains migrate with the people who carry them and can be spread whenever an infected person coughs them into the air. Hospital patients can spread them to doctors and nurses, school bus drivers can pass them along to students, airline passengers to their fellow travelers on a flight. The new strains evolve in large part because doctors and patients misuse antibiotics.
Resistant bacteria arise through a process called natural selection.
They eventually multiply until they predominate, creating a new strain of bacteria that aren't responsive to standard drugs. This process works the same way in bacteria that cause tuberculosis and in those that cause other diseases. Another form of behavior that promotes the development of antibiotic-resistant microbes is not taking the drugs as prescribed. Although you shouldn't take antibiotics needlessly, when these drugs are required to treat an infection, it's important to take each dose and to finish the prescription. To make sure antibiotics will keep working, everyone needs to use them with care.