All bacteria produce chemicals known as virulence factors. their ability to produce these molecules is what microbiologists mean when they talk about virulence. These virulence factors allow bacteria to do a range of things from hiding from the immune system to breaking into cells and even stealing nutrition from the victim cells. It is these virulence factors that separate the E. coli found in the stomach from the E. coli that gives you food poisoning. Some chemists have decided that targeting this virulence is a better solution to the problem than killing the bacteria outright. This would avoid the risk of developing drug resistant strains of pathogens as the bacteria would only be affected inside a human body and not in a lab. Hopefully in the future a set of drugs could be developed that targets and shuts down these virulence chemicals and allows the aggressive bacteria to starve to death, but it may be many years before we are even able to find a single chemical that works let alone the entire arsenal of antibacterial drugs we currently have.