Can Bacteria Cause Pain?

The common consensus on bacterial infections and pain has traditionally been that it is the body’s immune reaction that triggers a pain response, and not the bacteria themselves. But a new research study seems to be turning that idea on its head – stating that bacteria can trigger the body’s pain-sensing nerves. The news is causing quite a stir, especially after initial results showed that mice whose paws were infected with staph demonstrated signs of pain before a single immune cell arrived at the infection site. And, while immune cells do, in fact, release pain-causing molecules while they fight off microbial infection, it appears that bacteria themselves also cause pain. The discovery was largely a surprising one, as scientists were initially growing immune cells in the same dish as pain-sensing nerve cells. Introducing bacteria to the mix was supposed to activate the immune cells, but researchers were surprised to see an immediate reaction in the nerve pain cells instead. In other words, the nerve cells were directly reacting to the bacteria themselves. From there, scientists moved on to animal models; infecting paws of mice with Staphylococcus aureus – a bacterial infection known to cause painful sores in humans. Monitoring the tender and painful infection, it wasn’t long before their suspicions were confirmed. The mice demonstrated the most pain response and sensitivity when the bacterial cell numbers were at their highest (roughly 48 hours after infection), before the immune cells had a chance to kick in.