Study Urges Sterilization of Donor Tissue

Shortcomings found after death of man who had knee surgery

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HealthDay Reporter

WEDNESDAY, June 16, 2004 (HealthDayNews) -- A new study finds shortcomings in the safety of tissue donations, and experts are calling for stricter standards to prevent dangerous infections in recipients.

In 2001, a 23-year-old Minnesota man died three days after undergoing reconstructive knee surgery. The surgery had involved a bone cartilage graft which, it turned out, had been infected with the bacterium Clostridium sordellii.

After the death, the U.S. Centers for Disease Control and Prevention investigated tissue donations. The results of that probe, along with interim recommendations to improve the safety of tissue transplantation, appear in the June 17 issue of the New England Journal of Medicine.

The best way to avoid infection is by sterilization, the authors say, and both government regulations and industry standards for processing and testing allograft (from someone other than yourself) tissue need to be improved.

"The only definitive way to prevent infection is to sterilize all allografts," said Dr. Marion Kainer, lead author of the study, which was conducted while she was an epidemic intelligence service officer at the CDC in Atlanta. "We are hoping that the suggestions we are putting forward will be incorporated into future regulations and standards."

Others express the hope that these will be stopgap measures only, intended to see the industry through until scientists have the ability to create biologic tissues like that which was originally found in the body. "I think they are temporary," said Dr. Joseph F. Fetto, an associate professor of orthopedics at New York University School of Medicine. "The technology is not quite refined yet, but it's being done at an experimental laboratory level, and within a decade we have a good chance of applying it in a general way."

According to the article, in 2001 about 875,000 musculoskeletal allografts were distributed by U.S. tissue banks. As an accompanying perspective article points out, these transplants were usually life-enhancing rather than lifesaving.

Unlike blood banks, however, there isn't much regulatory oversight of tissue banks, leaving open the possibility of infection by various agents. There is an "increasing emergence of use of this technology, and there's very little in the way of regulation," explained Dr. Robin Patel, author of an accompanying perspective article and associate professor of medicine and microbiology at the Mayo Clinic.

For the current investigation, the researchers identified 14 patients who met the case definition for clostridium infection, all of whom had received allografts processed by "Tissue Bank A." The rates of clostridium infection were 0.12 percent among patients who received sports-medicine tissues and 0.36 percent among those who specifically received femoral condyles (part of the knee joint).

While only the one death was reported, 10 other patients required allograft removal, three were scheduled to have knee-replacement surgery due to intractable pain, and three ceased to be able to maintain full-time employment because of disability from the infection.

The infected tissue came from nine donors via seven tissue banks, but all of the allografts had been processed by Tissue Bank A.

In two cases, the bank exceeded industry standards mandating that tissue be recovered up to 24 hours after death, as long as the interval between death and refrigeration does not exceed 12 hours. Also, the bank did not sterilize tissues.

"The best way of preventing infections is sterilizing tissue," Kainer said. "It's not impossible. Most tissue can be sterilized."

The most common sterilization technique is gamma irradiation. "There are some problems associated with it, especially at high doses; it can impair the bone or tissue," Kainer said. "At lower doses, it is not so much of a problem."

Testing is a problem largely because bacteria are not uniformly distributed in the tissue. "The sensitivity of some swabs is only 20 to 40 percent," Kainer said. "Just because the swab is negative does not actually mean that the tissue is negative."

That fact highlights the importance of sterilization, she said. "My position is you should use a sterilization procedure if that is available. If you don't have a sterilization procedure, then the physician must know that the tissue is not sterile and the risk of infection associated with it. The patient must know that as well," Kainer said. "If people decide to use non-sterile tissue, there needs to be informed consent, and patients need to know an alternative is available. Many patients say, 'I was never told that this posed a risk to me. I was never told that there was an alternative which was safe.'"

More information

Visit the American Association of Tissue Banks for more on current industry standards.

SOURCES: Marion Kainer, M.D., medical epidemiologist and infectious disease physician, Tennessee Department of Health, Nashville; Joseph F. Fetto, M.D., associate professor of orthopedics, New York University School of Medicine, New York; Robin Patel, M.D., associate professor of medicine and microbiology, Mayo Clinic, Rochester, Minn.; March 15, 2002 Morbidity and Mortality Weekly Report; June 17, 2004 New England Journal of Medicine

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