You have 100 trillion microbes on your body right now.
A lot of readers were worried to learn that resistance to antibiotics now kills more people than AIDS, but while the evolution of superbugs is certainly a problem, it's good to remember that not all bacteria are bad. In fact, we wouldn't be able to live without them. PBS Digital Studios' It's Okay To Be Smart blog has a great video explaining our microbiomes.
Ever not felt completely like yourself? There's a good reason for that. Because a large part of you . . . isn't you. Our bodies are home to ten times as many microbes as human cells. We are walking ecosystems, each of us home to thousands of different species on and inside of us.
For a deeper dive into the role of good bacteria, read Carl Zimmer's great article on what antibiotics do to your body and why probiotics are so important.