The US pharmacy that made the tainted drugs leading to a widening meningitis outbreak was searched by criminal investigators, as the death toll from the outbreak rose to 16 people.
The search comes a day after the Food and Drug Administration (FDA) identified two new drugs produced by the New England Compounding Center (NECC) in Massachusetts that may have infected patients with the rare form of fungal meningitis.
"This is part of our ongoing investigation... to fully investigate the scope and cause of the outbreak of fungal meningitis," Sara Clark-Lynn, a spokeswoman for the FDA, told AFP.
Federal prosecutors joined the FDA's criminal investigation unit and other agencies looking into how three contaminated lots of steroids produced by NECC put 14,000 people in 23 states at risk. The drug is commonly injected into the spine to treat back pain.
"It is entirely premature to suggest what the results of the investigation will be," Carmen Ortiz, US Attorney for the district of Massachusetts, said in a statement.
The widening outbreak has led to calls for tighter regulation of the loosely controlled pharmaceutical compounding industry.
Critics say drug manufacturers have found a way to sidestep costly and strict oversight by classifying themselves as pharmacies, which are given freer rein to mix drug compounds for patients.
The FDA has not yet determined how many people are at risk of contracting the infection from other potentially tainted NECC drugs, but said the sterility of the facility's products is "of significant concern."
"During our thorough investigation, FDA has taken samples of compounded products, is reviewing the facility's compounding protocols, ascertaining from the firm where the products were sent, whether valid prescriptions were in place, analyzing samples submitted by clinics and health care professionals, and looking to determine what active pharmaceutical ingredients were used to produce the products," Clark-Lynn said.
The company had been warned by the FDA in 2006 that its practices were violating the rules and has also been under investigation by state authorities, who have the primary regulatory responsibility for pharmacies.
Meanwhile, the number of cases rose to 233 in 15 states Tuesday, including two cases of "peripheral joint infection," according to the latest tally by the Centers for Disease Control and Prevention.
That's up from 214 on Monday and 64 on October 6, when NECC voluntarily suspended operations and recalled all of its products.
Virginia said late Tuesday that its death toll had risen to two.
Health officials have warned it could be weeks or even months before authorities have a final tally of the infections, due to the deadly fungal infection's long incubation period.
Three patients who had been treated with two other drugs produced by NECC have also contracted fungal meningitis, prompting health officials to widen their outreach efforts.
The FDA cautioned that it has not yet confirmed that these three infections were caused by the NECC products.