Forever Unprepared — The Predictable Unpredictability of Pathogens

The recent behavior of two infamous pathogens — methicillin-resistant Staphylococcus aureus (MRSA) and this winter's pre-swine edition of influenza virus — has proved an embarrassment to scientists everywhere. Both organisms have flouted the most basic tenet of the field of infectious disease, our bedrock belief that resistance to antimicrobial agents is caused by exposure to those same antimicrobial agents. It is our version of Newton's third law, that for each action there is an equal and opposite reaction. And on this assumption we have built the entire public health approach to preventing the emergence of drug resistance: we preach, if . . .