Deadly Infections: How Bacteria and Drugs Fight in the Heart

When your heart gets infected by a nasty bug called Staphylococcus aureus, things can get really serious, really fast. About one in five people with this infection, called infective endocarditis, don't make it. This has been the sad truth for a long time, with no big improvements recently. Doctors often use two main drugs to fight this infection: antistaphylococcal penicillin and cefazolin. Both are thought to be equally good at their job. But here's where it gets tricky. Many of these bugs have a special gene called blaZ. This gene is like a shield that makes the bacteria tougher to kill with certain drugs. Some of these tough bugs show something called the inoculum effect. This means when there are a lot of bacteria, it takes more of the drug to stop them. In infective endocarditis, the infection can form lumps, called vegetations, in the heart. These lumps are packed with lots of bacteria. So, the inoculum effect could make treating these infections even harder.