Microbes can redeem themselves to fight disease

Normally, you wouldn’t want to have anything to do with Clostridium novyi.

The rod-shaped bacterium is commonly found in soil, manure or under rotting leaves. When it invades a human body, it releases flesh-eating toxins. The last place you would hope to find it is in a hospital.

But researchers used a modified version of this bacterium to destroy an advanced cancer that had spread to a patient’s shoulder. When injected directly into the shoulder tumor, the altered bacterium killed the cancer cells, sparing nearby healthy ones.

Another bad bacterium, Listeria monocytogenes, is a frequent culprit in serious foodborne illnesses. But the microbe is being tested in patients with several types of cancer. Engineered with special tumor-recognition molecules, Listeria prods the immune system into action, marshaling an attack against tumors that the body might otherwise be unable to combat.

True, these bacteria first had to be