Dear reader, you may owe your life to antibiotics. Or maybe your child, sister, brother, parent or grandparent survived a serious infection thanks to antibiotic medicine.Since Scottish scientist Alexander Fleming discovered penicillin in 1928, countless human lives have been spared the deadly effects of bacterial pathogens. Penicillin, the historic first of the therapeutic antibiotics, was pressed into widespread use in 1942, just in time to save hundreds of thousands of soldiers whose lives were more at risk from these invisible invaders than from enemy bullets and bombs in World War II.But this medical miracle, precisely because of its usefulness and popularity, created the conditions for its own nemesis, Dr. Marion Kainer, an infectious disease physician and epidemiologist with the Tennessee Department of Health, told The Rotary Club of McMinnville on Thursday.“Antibiotics are necessary for us to have surgery, for organ transplants and cancer therapies,” Kainer told the Rotarians.