A future without effective antibiotics for some infections is possible. Only 70 years ago, penicillin discovery have changed infectious diseases treatment, reducing deaths and illness. However, the high microbial adaptability has appeared few years later drug discovery: already in his Nobel Prize speech in 1945, Alexander Fleming, who discovered penicillin, warned that bacteria could become resistant to these remarkable substances. Between 1940 and 1990, 29 classes of antibiotics with different mechanisms of action have been discovered and