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.
A spokesman for the US Food and Drug Administration, Sarah Clark-Lynn, said in an e-mail that the “majority of vials” from the first lot tested exhibited fungal growth, meaning that the contamination was not an isolated incident.
She said the CDC used genetic testing to confirm the presence of Exserohilum rostratum, but not how many vials were found to contain this fungus.
By Wednesday, all but two of the meningitis patients with laboratory-confirmed cases had been infected with Exserohilum, the CDC said.
Previously, health officials had said they found fungus in a single vial of steroid from New England Compounding, but they had not pinpointed the type.
Thursday’s announcement ties the pharmacy more closely to the outbreak.
“The laboratory confirmation further links steroid injections from these lots from NECC to the multistate outbreak of fungal meningitis and joint infections,” the CDC statement said. “Testing on the other two implicated lots of methylprednisolone acetate and other NECC injectables continues.”
Dr. William Schaffner, an infectious disease specialist with Vanderbilt University School of Medicine in Nashville, said that the latest findings are a “smoking gun” that provides the critical scientific confirmation that the fungal contamination came from New England Compounding.
“Given that the vial was unopened, it means that there’s no way that external contamination could have occurred after the manufacture of the product,” Schaffner said.
One key question that remains unanswered, said Schaffner, is how the products were contaminated at the Framingham pharmacy. Contamination may have been in the vials the company used, the raw materials it used to make the steroid, or perhaps in the New England Compounding plant, he said.
The types of fungal meningitis in patients sickened in the outbreak are so unusual that there is very little written about them in medical textbooks and most physicians never encounter a single case. Yet all of the patients who are ill with these rare infections were treated with New England Compounding injectable steroids, Schaffner said.
“Once you put all those pieces of investigation together, there is only one way the equation solves,” he said.
New England Compounding released a statement Thursday saying the company is “eager to review” the latest findings as part of its “continued cooperation with the CDC and FDA.”
“NECC is earnestly focused on determining, along with these agencies, the cause of contamination in vials of this product and to rapidly and professionally carry out a recall to remove all NECC products from circulation,” the statement said.
Federal health officials estimate that approximately 14,000 patients may have received injections with medication from the three implicated lots of methylprednisolone between May 21 and Sept. 26, when the steroid was recalled.
They said nearly 97 percent of these patients have been contacted for further follow-up.
Patients received the injectable steroid to treat back and joint pain. To date, 257 people nationwide have been sickened, mostly with meningitis, but also some with joint infections, the CDC said Thursday. Twenty people have died. New Hampshire, with eight, is the only New England state with reported cases.
Since the outbreak was publicly linked to New England Compounding earlier this month, federal regulators have expanded their focus from the three suspect steroid lots to all injectable medications sold by the company, though they have not linked any other products to confirmed infections.
On Monday, they urged physicians to follow up with patients who received any of the company’s injectable products after May 21, “out of an abundance of caution.”
As the numbers of infections rise daily, Schaffner said 10 state health departments — including those in Connecticut, New York, and California — are planning to explore whether patients may have been sickened with fungal infections by New England Compounding products earlier than May 21.
Tennessee, the hardest hit state with 63 people infected and eight deaths, will be looking as far back as Jan. 1, Schaffner said.
Massachusetts will not be joining that effort, said Public Health Department spokesman David Kibbe. “We remain focused on the current investigation,” he said in e-mail.
As part of the state’s joint investigation with federal officials, a Westborough pharmacy, Ameridose,which shares the same owners as New England Compounding, agreed to suspend all production on Oct. 10 to allow investigators time to ensure that its products were not contaminated.
That agreement expires at 5 p.m. Monday.
Kibbe said no decision has been made about whether Ameridose will resume operations after Monday.Kay Lazar can be reached at firstname.lastname@example.org. Follow her on Twitter @GlobeKayLazar.