According to Bloomberg, Optimer Pharmaceuticals won FDA approval for the first antibiotic in a quarter-century that fights a deadly bacterium linked to intestinal infections often caught in hospitals. Optimer will sell the drug fidaxomicin under the name Dificid. Dificid will be San Diego-based Optimer’s initial product and the first drug cleared in more than 25 years for Clostridium difficile, which attacks the lining of the colon and can cause severe diarrhea. The germ sickens about, 500,000 a year in the U.S. and kills about 30,000. Optimer plans to start selling the treatment as early as July. Sales of the drug may surpass $217 million in 2015, according to the average estimate of three analysts surveyed by Bloomberg. The treatment may generate as much as $500 million worldwide.