Each year, approximately 1.5 million musculoskeletal allografts are distributed for transplantation1. Allograft tissues offer advantages over autografts, such as smaller surgical incisions, reduced operative times, and lack of donor-site morbidity2. A disadvantage of allografts is the potential, albeit low, for disease transmission. Recent investigations have implicated a variety of allografts in the transmission of several microorganisms3-7. We investigated the occurrence of invasive group-A streptococcal disease in a musculoskeletal allograft recipient.
Investigation of the Infected Allograft Recipient
Apreviously healthy seventeen-year-old boy underwent anterior cruciate ligament repair with implantation of a hemi patellar tendon allograft. The following day, pain and erythema developed at the surgical site and the patient had a fever of as much as 39°C. Six days after the procedure, he underwent surgical exploration with arthrotomy of the knee and fasciotomy of the thigh. The allograft tissue was removed. Cultures of the wound aspirate, blood, and explanted tissue demonstrated growth of group-A streptococci.
The postoperative course of the patient was complicated by fluid collection in the affected thigh and knee and persistent fever. Six days after allograft explantation, needle aspiration of the knee yielded fluid which, when sent for culture, demonstrated group-A streptococci, despite a week of treatment with clindamycin and cefazolin. The patient received intravenous antibiotics in the hospital for seventeen days and was discharged with an indwelling venous catheter for continued antibiotic treatment at home.
Investigation of the Allograft Donor
We reviewed the medical records and the autopsy report of the allograft donor, which stated that he had been a healthy man in his thirties who had died three weeks after undergoing elective cervical spinal fusion for degenerative disc disease. Three days before his death, the donor had presented to an emergency department with a diffuse pruritic rash, which was diagnosed as an allergic reaction to medications. The donor then returned to the emergency department three days later because of back pain, nausea, and vomiting, and he died soon after that. The autopsy findings included a generalized rash and potentially toxic levels of a muscle relaxant and an analgesic medication. In the report made by the medical examiner, death had been attributed to the toxic effects of the drugs. No cultures had been performed.
After the growth of group-A streptococci was demonstrated in the tissue cultures from the allograft recipient, autopsy specimens from the donor were sent to the United States Centers for Disease Control and Prevention (CDC). Immunohistochemical testing was performed with use of a two-step indirect immuno-alkaline phosphatase technique with an antibody against group-A streptococci and with appropriate controls8,9, and bacterial cultures were performed on a stored blood specimen from the donor.
The evaluation performed by the CDC demonstrated Gram-positive cocci in dermal blood vessels. Immunohistochemical studies revealed the intracellular and extracellular presence of group-A streptococci in these vessels as well as in the lungs. In addition, group-A streptococci were isolated from a culture of blood from the donor. On the basis of these findings along with the previously noted rash, the cause of death of the donor was amended to streptococcal toxic shock-like syndrome. The source of the group-A streptococcal infection in the donor could not be identified.
Tissue Traceback and Testing
We reviewed files from the tissue-recovery organization and from the two tissue processors (referred to in this paper as tissue-processor A and tissue-processor B) that had received tissues from the donor.
Donor allografts were recovered by a single organization that, at the time of recovery, placed twelve specimens from the allografts into culture medium. All twelve cultures demonstrated growth of group-A streptococci. The recovery organization distributed twenty musculoskeletal allografts from the donor to tissue-processor A and ten to tissue-processor B.
Six of the allografts were rejected by tissue-processor A because they did not meet physical specifications (e.g., the blood-vessel diameter was too small or the allograft was damaged). Tissue-processor A placed specimens from the remaining fourteen allografts into culture medium before processing, and group-A streptococci grew on all cultures. The donor allografts were then processed with a proprietary antimicrobial solution (but not subjected to high-temperature or high-pressure disinfection methods), and tissue specimens were again taken from the donor allografts and placed in culture medium. These cultures demonstrated no growth, and the allografts were released for transplantation. Tissue-processor B did not process or distribute any allografts from the donor because the donor did not meet eligibility requirements due to past foreign travel.
After receiving notification of the infection in the allograft recipient, tissue-processor A recalled all non-implanted processed allografts from that particular donor. The recalled tissues were immersed in thioglycolate broth, which was incubated for twenty-one days. No organisms were recovered following the twenty-one-day incubation. Tissue-processor B, which had not processed any tissues from the donor, provided the unprocessed tissues to the CDC. Tissue samples from tissue-processor B were ground in Todd-Hewitt broth and dispensed in test tubes containing Todd-Hewitt broth with defibrinated sheep blood. Samples were streaked onto blood-agar plates with and without gentamicin (2.5 mg/L). Group-A streptococci were recovered by the CDC from multiple samples of the recalled allograft tissue provided to them by tissue-processor B.
PathoDx strep grouping latex agglutination tests (Remel, Lenexa, Kansas) were used to evaluate the organisms that were recovered from tissues provided by tissue-processor B, and the same tests were used to evaluate the organisms that were recovered from the blood and explanted tissues of the infected recipient and that had demonstrated beta-hemolysis on blood-agar plates. Specimens identified as group-A streptococcal bacteria underwent T-protein serotyping (T-typing) and emm-gene sequence typing (emm typing). T-typing is an antigen-antibody agglutination reaction that is visualized with use of suspensions of group-A streptococcal cells10, and emm typing involves sequencing the 150-base variable region of the emm gene, which encodes the M protein, a major virulence factor11. With use of a database maintained by the Streptococcal Genetics Laboratory of the CDC, we compared sequences from group-A streptococcal isolates obtained during our investigation to more than 400 emm gene sequences, representing more than 1000 invasive group-A streptococcal isolates12.
Group-A streptococcal isolates from the blood and tissue of the donor as well as the recipient were T-type 3-13 and M protein gene type 3 (emm3). These isolates were indistinguishable by emm typing and represented a novel subtype, emm3.17.
Investigation of Other Allograft Recipients
A total of six musculoskeletal allografts processed by tissue-processor A had been implanted, including the allograft received by the patient presented in this report. We reviewed the medical and surgical records and interviewed the health-care providers of the five other allograft recipients. The tissues that had been implanted included other hemi patellar tendons, tibialis tendons, and a peroneus tendon. No adverse outcomes were detected in the other five recipients.
Our investigation demonstrated an infection with a novel strain of group-A streptococci due to transplanted musculoskeletal allograft tissues recovered from a cadaveric donor. This is the first laboratory-confirmed report of group-A streptococcal transmission from implanted allograft tissues. In our investigation, isolation of a novel subtype of these bacteria in both the allograft donor and the allograft recipient confirmed transmission. The recovery of the rare subtype emm3.17 from normally sterile specimens of both the tissue donor and the tissue recipient provides very strong evidence that the isolates were linked. The Streptococcus Genetics Laboratory at the CDC has performed sequence analysis of more than 800 type emm3 clinical isolates (invasive and noninvasive) since the year 2000 and has documented forty-one different emm3 subtypes from its surveillance and from sequences submitted to it from multiple countries. The isolates described in this report were the only subtype emm3.17 isolates that the CDC has encountered.
Invasive group-A streptococcal disease is associated most commonly with skin and other soft-tissue infections as well as bacteremia without an identified source13. It is a rare cause of surgical-site infections, accounting for less than 0.4% of such infections reported between 1998 and 2002 to the National Nosocomial Infections Surveillance System at the CDC (unpublished data).
Two key events led to the transmission of infection in this patient. First, the donor's death initially was not attributed to infection. United States Food and Drug Administration (FDA) donor-screening guidelines recommend rejection of tissue donors who have known or suspected sepsis at the time of death14. However, infections in tissue donors may not be recognized. Infection in this donor was not detected by clinical evaluation or initial autopsy. The availability of autopsy specimens was particularly important in this investigation, as it allowed for testing which ultimately led to identification of the cause of death of the donor.
Second, evidence of group-A streptococci in the allograft tissue at the preprocessing stage did not prompt tissue-processor A to reject the allografts, as repeat cultures performed after processing showed no evidence of the organism. However, previous reports of allograft-associated infections have highlighted problems with regard to tissue-processing with antimicrobial solutions and with regard to the culturing methods used to detect bacterial contamination after processing. In one case, antimicrobial treatment did not eradicate Clostridium sordellii from allograft tissues and post-processing cultures failed to detect the contamination because residual antimicrobial agents interfered with the culture results7.
Two measures might help address the events that led to this case and improve the overall safety of allograft tissues. First, because some organisms are particularly virulent or difficult to eradicate, their presence in donor tissues should prompt consideration of rejecting those tissues unless a validated sterilizing method can be applied. In January 2005, the American Association of Tissue Banks specified several “high-virulence organisms” which, when detected in pre-processing cultures, necessitate rejection or sterilization of individual tissues. Group-A streptococci are included on this list when isolated from cardiac, vascular, musculoskeletal, and osteoarticular tissues15. In consideration of the fact that, at the preprocessing stage, cultures of blood and musculoskeletal tissues from more than 1200 donors at one tissue bank demonstrated growth of this organism in only 0.02% of cultures16, the rejection of tissues with positive cultures for group-A streptococci will have little impact on the supply of tissues.
Second, to identify infections in potential donors, assessment of donor eligibility should continue throughout the recovery and processing phases of allograft preparation. Findings of a common organism in multiple cultures at the preprocessing stage should prompt reevaluation of the clinical history of the donor, as these findings may be consistent with systemic infection. In this case, additional review might have led to an increased suspicion of group-A streptococcal sepsis in the donor.
Findings from this investigation and others have contributed to the development of new procedures at tissue-processor A and to the implementation of new industry standards and FDA regulations and guidance for the tissue industry. Tissue-processor A now routinely reevaluates the medical history of a donor when there are any positive culture results at the preprocessing stage. At a national level, in May 2005, the FDA finalized the last of three rules that were developed to improve the safety of human-tissue transplants17.
The guidelines set by the CDC with regard to the prevention of group-A streptococcal disease identify the occurrence of postsurgical infection with this organism as a sentinel event that should prompt investigation and enhanced surveillance18. Some postsurgical group-A streptococcal infections reflect transmission from asymptomatic but colonized healthcare workers. However, given the findings in this case, contaminated allografts should also be considered potential sources of this organism when postsurgical infections are recognized. Because many allografts can be harvested from each donor, it is important that clinicians immediately report possible allograft-associated infection to the tissue processor, local health department, FDA, and CDC so that the potential problem can be promptly investigated. ▪
Disclosure: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. No commercial entity paid or directed, or agreed to pay or direct, any benefits to any research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.
The views presented here are those of the authors and should not be construed as reflecting the views of the Centers for Disease Control and Prevention or Food and Drug Administration.
Investigation performed at the Centers for Disease Control and Prevention, Atlanta, Georgia
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