Federal health officials said they have confirmed the presence of a fungus known as Exserohilum rostratum in unopened vials of the steroid medications linked to the deadly U.S. meningitis outbreak.

The Centers for Disease Control and Prevention and the Food and Drug Administration said Thursday that one of three lots of preservative-free methylprednisolone acetate from the New England Compounding Center tested positive for the fungus.  More testing is planned for the other two lots implicated in the outbreak.

The CDC and state health departments have estimated that approximately 14,000 may have received injections containing contaminated medication.  Nearly 97 percent of these patients have been contacted for follow-up.

The government organization is encouraging clinicians to report any adverse events following the use of these products to the FDA’s MedWatch program.