An outbreak of tuberculosis linked to contaminated bone graft material has killed one person and infected at least four others, say American health officials, who are battling to control the second outbreak of this rare disease in two years.
Eight people died in 2021 when the same type of bone repair product used in spinal surgery was also contaminated with the bacteria that causes TB. The product was supplied by US company Aziyo Biologics, the company also involved in the current outbreak.
The contaminated product was used in at least 36 patients who had surgical or dental procedures earlier this year, according to the US Centres for Disease Control and Prevention (CDC).
But the outbreak did not become public until Aziyo issued a voluntary recall on 13 July, reports The Washington Post.
All patients are being treated as if they have TB because of the large percentage of people who develop severe forms of the disease from implanted bone material, said Kathleen Conley, a CDC spokesperson.
In 2021, surgeons used the contaminated material in 113 patients, sparking a wave of litigation and calls for tighter regulation of the product, a commonly used surgical putty that contains living cells procured from the bones of a cadaver.
In the current outbreak, the bone products were derived from a single donor and sent to 13 facilities in seven states between February and June, said the CDC.
Aziyo recalled a single lot of the bone repair product, ViBone Moldable, which is made from human tissue and used primarily in orthopaedic and spinal procedures, according to a 13 July company statement, which said samples from the lot had tested negative for the bacteria that causes TB.
The CDC said the company’s bone grafting solution, called alloOss Plus, used for dental procedures, also came from the same donor and was recalled.
The company has suspended shipments of all bone repair products from all donors, and all patients, facilities and states involved have been contacted, with the remaining units of the product lot having been removed from inventory.
Aziyo, which processes the bone product, is responsible for ensuring the product is free of contamination. But current US regulations do not require organ or tissue donors to be assessed for TB or TB risk factors.
The US Food and Drug Administration (FDA) requires human tissue used for products like the bone repair material to be tested for several communicable diseases, including hepatitis, HIV and syphilis – but not tuberculosis.
Nor is laboratory testing for the TB bacteria routinely performed on donors, according to a report on the 2021 outbreak published in The Lancet Infectious Diseases. Its authors include CDC, FDA and other federal and state health officials who investigated that outbreak, the largest recorded tissue-derived TB outbreak, the report said.
Standard screening was unsuccessful at detecting infection in donated tissues as well as in the donor, an 80-year-old man who travelled frequently to an unidentified country where the annual number of new TB cases is more than eight times higher than in the US, the report said.
In that report, health officials recommended that “all prospective tissues and donors should be routinely assessed for TB risk factors and clinical findings”.
In a recent statement, Aziyo said neither the FDA nor the American Association of Tissue Banks, the organisation that promotes the safety and use of donated human tissue, mandate testing for the TB bacteria in cellular products.
“However, considering our experience in 2021 and with the intent to protect patients, Aziyo worked with outside experts to develop a test to screen for (the bacteria) where none was previously commercially available,” the company said. “We have used this test as part of our standard operating procedures since that time. This test exceeds guidelines set by both the AATB and the FDA.”
The company said samples from the specific lot of bone material that was related to the infections had tested negative by an independent laboratory using a nucleic acid test designed to specifically detect the organism.
“Our investigation has involved additional testing on the donor lot in question through multiple independent labs and in each instance, (the bacteria) has not been detected in the samples,” the company said.
Beverly Bliss, vice-president for accreditation standards and regulatory affairs at the American Association of Tissue Banks, agreed that even a more sensitive laboratory test, which would take six to eight weeks, is not guaranteed to turn up TB in bones. And that length of time might threaten the live cells in the Aziyo product.
“There simply isn’t a good test,” she said. Current tests were “all designed for living people”.
The FDA said it was working with the CDC “to fully understand the impact of this recall”, said Carly Kempler, an FDA spokesperson.
On whether the agency planed to update its human tissue requirements and mandate testing for TB, Kempler said the agency routinely reviews its approaches for screening and testing of human cells, tissues and cellular and tissue-based products from donors to determine whether any changes should be made.
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