Your pregnant neighbor has a sore throat and tells you that she is taking some "leftover" tetracycline from a previous infection. Give her two reasons why this is a poor decision. Another woman has been prescribed a broad-spectrum oral cephalosporin for a sore throat. What are some consequences in addition to the cure of the infected throat? Finally, a man has a severe case of gastroenteritis that is negative for bacterial pathogens. A physician prescribes an oral antibiotic. What are your opinions of this therapy?