Once upon a time, Mr. Alberto, a man of advanced age, but active, had a fall, fractured his left leg, and had surgery. He was in hospital for a week and, when he was about to be discharged, he had symptoms like fever and respiratory complaints, so he had to stay in the hospital. The tests performed showed that he had pneumonia and, even before the identification of the causing microbe, he got the antibiotic treatment that is usually prescribed for this disease. After three days, Mr. Alberto still had fever and respiratory symptoms. The tests showed that the infection was generated by a bacterium, a staphylococcus, resistant to the administered antibiotics. A new antibiotic was prescribed, and after another week and a half of treatment in the hospital, Mr. Alberto was able to return home.