Friday's FDA approval of the latest new antibiotic by Cubist Pharmaceuticals is a step toward combating a problem estimated to kill 10 million people and cost $100 trillion globally by 2050. Late Friday, U.S. regulators gave the nod to Zerbaxa, formerly known by the generic name of ceftolozane/tazobactam, for the treatment of adults with complicated urinary tract infections and complicated intra-abdominal infections caused by certain so-called Gram-negative bacteria, typically considered among the hardest to kill.