Fungal contamination found in medication vials from the Framingham pharmacy at the heart of the ­national meningitis outbreak matches the type of fungus making most people sick, federal health officials said Thursday, a finding that one ­infectious disease specialist labeled a “smoking gun.”

The US Centers for Disease ­Control and Prevention said in a statement that it found a fungus known as Exserohilum rostratum in unopened vials of the steroid methylprednisolone acetate shipped by New England Compounding Center. The vials were among more than 17,000 doses of the injectable steroid contained in three suspect lots sent to clinics in 23 states.