Drug resistance mechanisms refer to the ways in which microorganisms, such as bacteria and viruses, adapt to survive despite the presence of medications designed to eliminate them. These mechanisms can include genetic mutations that alter the target of the drug, the production of enzymes that deactivate the drug, or changes in cell permeability that prevent the drug from entering the cell. Another common mechanism is the efflux pump, which actively expels the drug from the cell before it can exert its effects. Understanding these mechanisms is crucial for developing new treatments and combating issues like antibiotic resistance and viral resistance in diseases such as HIV and tuberculosis.