The US FDA has approved the antibiotic moxifloxacin (Avelox, Bayer Healthcare Pharmaceuticals) to treat two forms of plague, a rare but sometimes fatal bacterial infection that surfaced last year in Colorado and possibly spread through human-to-human contact, the agency announced.

The three most common forms of plague are bubonic plague, a lymph node infection; septicemic plague, a blood infection; and pneumonic plague, a lung infection that can cause death within 24 hours if left untreated.

The FDA approved moxifloxacin for septicemic and pneumonic plague, but not for bubonic plague, an indication that Bayer Healthcare Pharmaceuticals did not apply for.

Last summer, four people in Colorado contracted plague, but survived after treatment. More recently, Madagascar experienced a plague outbreak that killed 71 people from September 2014 through mid-February.