Health official worldwide are concerned by a resurgence of diseases caused by bacteria that are resistant to standard antibiotics. for instance, antibiotics resistant bacteria are now causing an epidemic of TB . Drugs can relieve symptoms in a few weeks, but it takes much longer to halt the infection, and patients are likely to discontinue treatment while bacteria are still present. why can prakaryotes quickly re infect a patient if they are not wiped out? how might this result in the evolution of drug resistant pathogens?