Nov 18 2008
Streptococcus pyogenes
Streptococcus pyogenes
Description: Streptococcus pyogenes is a small (0.5 to 2.0 µm) spherical, non-motile, bacterial species. The Centers of Disease Control and Prevention (CDC) estimates that about 10,000 to 15,000 people in the United States develop S. pyogenes illnesses each year, and about 2,000 die. As with many other diseases, infants, the elderly, and those with underlying health problems are the most susceptible.
Invasive infections occur when the bacterial cells break through an infected person’s immune defenses. This may occur when a person has sores or other breaks in the skin that allow the bacterial cells to get into the tissue (e.g., child bed fever), or when the person’s ability to fight off the infection is decreased because of chronic illness or a condition that affects the immune system.
In September 2003, a previously healthy 17-year-old male underwent elective anterior cruciate ligament (ACL) repair with a tendon graft at an ambulatory surgical center in Colorado. Six days after the procedure, he was admitted to a local hospital with pain and skin redness at the incision site, fever of 39°C (102°F), and chills. The graft tissue was removed, and the patient underwent surgical exploration and additional tissue removal of the affected thigh.
Cultures of his blood, wound fluid, and removed tissue grew a small, spherical bacterium with the cells appearing in chains. The microbe was identified as Streptococcus pyogene. His hospital course required a stay in the intensive care unit and was complicated by persistent fever and fluid collection in the affected leg, which was managed with computerized tomography - guided needle aspiration. After 7 days of treatment with the antibiotics clindamycin and cefazolin, the wound fluid again yielded more streptococci. The patient was discharged afer 17 days and complete a course of intraveneous antibiotics at home; he was later readmitted to the hosptial for related complications and discharged subsequently.
The tendon graft received by the patient came from a cadaveric donor. After the patient’s surgeon was alerted to this case of presumptive graft infection, the Food and Drug Administration (FDA) was notified. Tendon grafts from the donor had been implanted in five other patients; however, as of December 1, 2003, no adverse outcomes had been detected by their surgeons. All remaining grafts recovered from the donor and processed for graft transplant were placed on hold or recalled.
According to the medical examiner’s records, the donor had undergone cervical spinal fusion three weeks before his death; autopsy findings included a generalized rash and potentially toxic levels of a muscle relaxant and an analgestic medication. On autopsy, the cause of death was attributed to the toxic effects of these drugs.
Cultures of the donor’s tissues, obtained by the tissue recovery organization before distribution to two tissue processors, again yieldedstreptococcal cells. The company that processed the grafts reportedly used aseptic technique and an antimicrobial solution, but no sterilization procedure was used. After the recovered tissues were processed, all post-processing cultures were reported as negative, and these grafts were distributed. Other tissues recovered from the donor were distributed to a second tissue processor and were held for further review.
The Centers for Disease Control and Prevention (CDC), FDA, and the Colorado Department of Public Health and Environment conducted an investigation to determine whether the tendon graft had been the source of infection in the recipient. The processing companies provided CDC with donor tissues that had not undergone antimicrobial processing; identical S. pyogenes cells were identified in the specimens as well as from the donor’s blood, which had been stored by the tissue processing company. DNA sequence analysis confirmed that blood and tissue bacterial isolates from both donor and recipient were a newly discovered subtype of S. pyogenes that had not been identified previously.
-Dr. Pommerville-
