More than 2.8 million drug-resistant infections are reported in the United States every year. Europe loses tens of thousands of people to them annually, and the standard forecast is grim: if nothing changes, antimicrobial resistance could kill around ten million people a year worldwide by 2050. The organism at the center of most of those hospital nightmares is the Gram-negative bacterium. These bugs cause a large share of the infections people pick up in hospitals, nursing homes, and ICUs. The reason they’re so stubborn is structural. They wear an outer membrane that blocks most antibiotics from even getting in, and they carry enzymes and pumps that dismantle whatever does make…