n investigation into three deaths last
month in Minnesota after routine knee surgery has left two cases unexplained
but has made an ominous finding in the third: that donor tissue commonly used
in certain knee operations can spread life- threatening infections.
The Centers for Disease Control and Prevention reported yesterday that the
third patient, a 23-year-old man killed by a rare bacterium usually found in
soil and fecal matter, appears to have contracted the infection from
cartilage taken from a cadaver and used to repair his knee.
Moreover, four other people in Florida and Louisiana who had surgery last
year to repair torn knee ligaments also developed severe infections from
donor tissue carrying other less rare but very dangerous bacteria. None died.
This is the first report that donor tissue for knee surgery can cause
illness or death, said Dr. Daniel Jernigan, a medical epidemiologist at the
disease centers. The investigation has not demonstrated exactly when or where
the donor tissues were infected, he said. The donors could have been infected
at the time of death, or contamination could have occurred as tissues were
collected, shipped, treated or implanted. One company that handles cadaver
tissue admitted that human error could have introduced bacteria.
The findings shed light on tissue banks, which include private companies
and nonprofits that process cadaver tissue for transplantation and supply it
to surgeons. This year the Food and Drug Administration required tissue banks
to register and list their products, said Dr. Martha Wells, an F.D.A.
regulatory scientist. The agency also proposed new rules for determining
donor suitability and carrying out good practices in handling tissues, which
range from hearts to finger bones.
While tissue banks are required to screen donors for H.I.V., hepatitis B
and C and other blood borne viruses, Dr. Jernigan said, they are not required
to report when those tissues cause other infections. Nor are they required to
culture donor tissue for bacterial diseases.
Of the estimated 150 tissue banks, half are members of the American
Association of Tissue Banks, which accredits tissue banks that voluntarily
follow its standards. Unaccredited tissue banks are not required to comply
with external quality requirements beyond routine screening for viruses.
In 1999, the banks distributed about 750,000 tissue specimens for
transplantation. Infections are rare, Dr. Jernigan said, but problems are
difficult to track because tissues are often collected in one state, stored
in another and transplanted into patients in several other states.
Dr. William Tipton, executive director of the the American Academy of
Orthopedic Surgeons, said doctors often choose transplanted tissue over
complicated surgery using the patients own tissues to repair knee ligaments
and damaged cartilage.
At least 50,000 people each year, many of them young, need this surgery,
although how many receive donor tissue is not known.
If an infection sets in after surgery, Dr. Tipton said, many surgeons
would look to sources other than the grafted tissue as the cause.
The Minnesota man's death may change that, said Dr. Harry Hull, the
state's epidemiologist. Blood and tissue samples show that the man died from
infection with Clostridium sordellii, a rare bacterium found in intestines
and soil. No evidence could be found that the bacterium came from the
operating room or treatment afterward, Dr. Hull said.
But sample tissue from the donor's other knee is infected with a strain of
Clostridia, a family of bacteria that cause tetanus. Which strain of the
bacterium is not yet known. A spokesman for CryoLife Inc., the Atlanta
company that provided the donor tissue, said that clostridia are extremely
common and that no proof exists that their tissue killed the Minnesota man.
Tissues from the same donor were implanted into eight other people in several
states, none of whom has died, the spokesman said. But Dr. Jernigan said that
one of the eight developed a severe knee infection. It is not known if
Clostridium sordellii is the culprit.
But in looking for cases of Clostridium sordellii infections after knee
surgery, Dr. Jernigan said that "a handful of cases" had cropped up
in several states. No one has died and the cases are still being
investigated. Several tissue banks are involved.
After surgery to repair knee ligaments, four patients in Florida and
Louisiana suffered infections from at least five strains of bacteria. Two
tissue banks have been implicated; one admitted that it had not fully
sterilized the tissues.
Dr. Hull said that the source of the
Clostridium sordellii in Minnesota is not known, but that it theoretically
could have come from the donor's body after death. Meanwhile, the other two
deaths, which occurred a week after routine knee surgery, which does not use
cadaver tissue, remain a mystery.
