Antimicrobial resistance

"Infectious disease is merely a disagreeable instance of a widely prevalent tendency of all living creatures to save themselves the bother of building, by their own efforts, the things they require. Whenever they find it possible to take advantage of the constructive labors of others, this is the path of least resistance. The plant does the work with its roots and its green leaves. The cow eats the plant. Man eats both of them; and bacteria (or investment bankers) eat the man" ― Hans Zinsser, Rats, Lice and History

Since the development of modern medicine in the early 20th century, the quality of life has risen greatly.  Ever since people began to live in cities, close proximity has allowed disease to spread easily.  Medicine was able to reverse this trend for the first time; however, an important tool in the fight against disease is rapidly loosing efficacy.  Bacteria are developing resistance to common antibiotics.

Evolution is an incredibly powerful force.  For every bacterium, roughly one genetic mutation will arise every two days.  The number of bacteria in the world is staggering.  In your body, alone, there are on the order of 100 trillion bacteria.  Not all mutations will lead to resistance to antibiotics—in fact, not all of these mutations will even be favorable.  Bacteria, however, also posses the ability to take share genetic information.  With both of these properties, antimicrobial resistance is seemingly inevitable.

This isn't the end of the story.  As I said, antibiotics are only one tool for controlling disease.  Sanitation will become increasingly important.  We already have the ability to treat drinking water and dispose of sewage and other waste.  Hand washing can effectively combat disease transmission, even without antibacterial soap, and alcohol-based hand sanitizer can still be made widely available.  Controlling pests is a second tool at our disposal.  Insects, such as mosquitoes, are perhaps the worst vector for disease, and have been responsible for countless pandemics throughout history.  Vaccination is yet another tool—be sure to share this with any anti-vaxer you know, they certainly are in need of education.  By augmenting our immune systems, certain infectious disease have become very rare, and small pox has been eradicated completely.

At the same time, this is still a substantial problem.  The number of deaths that could occur in the coming decades due to infectious disease is staggering.  Those most susceptible to death by infection are infants, the elderly, or those with otherwise compromised immune systems—three groups whose numbers have grown thanks to antibiotics.  Though otherwise healthy individuals likely won't succumb to infection, the toll in human suffering should not be underestimated.