A bout of Salmonella food poisoning isn’t a pretty affair. Your digestive tract churns, you can’t keep your food down, and you feel exhausted. But you aren’t the only one affected. Your gut contains trillions of bacteria, which outnumber your own cells by ten to one. They are your partners in life, and they are also transformed by the presence of the invading Salmonella.

Minority members of this intestinal community start to bloom, greatly increasing in number as the guts around them become inflamed. And these gut bacteria start to trade genes with Salmonella.

These swaps are a regular part of bacterial life. In their version of sex, two cells become united by a physical bridge, through which they shunt rings