The US outbreak has killed 20 patients and sickened more than 250 others who received the injections to relieve back pain.
US health officials have confirmed the presence of a deadly fungus in steroids linked to the national meningitis outbreak.
The Food and Drug Administration (FDA) said it had so far detected the rare Exserohilum fungus in one batch of methylprednisolone acetate, supplied by the New England Compounding Centre (NECC) to treat back pain.
“Now we can definitively say that the injections are linked to the infection,” Dr Tom Chiller, an epidemiologist with the US Centres for Disease Control and Prevention (CDC), said.
“To date, CDC has no firm evidence of infection in any patients beyond those exposed to the contaminated lots.”
The NECC has recalled about 17,700 single-dose vials of the steroid sent to clinics in 23 states.
As many as 14,000 people were given injections and are at risk of infection.
The company’s offices in the Boston suburb of Framingham were raided by federal investigators on Tuesday.
The CDC said on Thursday that 20 people have died in the outbreak, while nine new cases brought the national total to 254, including the first in New York, which became the 16th state with confirmed infections.
Patients who feel ill and are concerned they were injected with one of the recalled products are being urged to contact their doctor immediately.
Symptoms of fungal meningitis include new or worsening headaches, fever, sensitivity to light, stiff neck, weakness or numbness in any part of the body, slurred speech, increased pain, redness or swelling at the injection site.