Almost all bacterial infections clear up without treatment, given enough time. For most of human history
, before antibiotics, most people with pneumonia, scarlet fever
, cholera, dystentery, and so on recovered. (Tuberculosis and syphilis are exceptions, however. They persist until antibiotics are taken.) For gonorrhea and chlamydia, it usually takes several months, sometimes a year or more; other times, an infection may clear up in a few weeks.