Toxic shock syndrome due to Streptococcus pyogenes in a post-knee arthroplasty patient: a case report

Introduction: Prosthetic joint infections are usually caused by Staphylococcus aureus and coagulase-negative staphylococci. Streptococcus pyogenes prosthetic joint infection is extremely rare with only very few reported cases in the literature, yet it causes significant morbidity and mortality.

Presentation of Case: An 80-year old male who had a history of bilateral knee arthroplasty two years prior to consult presented with right knee swelling for one week. The patient had a one-month history of minor trauma on the right knee after tripping and landing on the knee sustaining minor abrasions. Progressive swelling, severe pain and limitation of range of motion was noted and the patient further developed fever, weakness and loss of appetite. Synovial fluid and blood cultures both revealed heavy growth of Streptococcus pyogenes. Antibiotics were shifted to Clindamycin and Penicillin G. However the patient’s status deteriorated and developed hypotension with episodes of hematochezia and further worsened to Toxic Shock Syndrome.

Discussion: Prosthetic Joint infection is one of the most serious complications of prosthetic joint implantation and is one of the leading causes of arthroplasty failure. Streptococcus pyogenes is an aerobic gram positive coccus that rarely causes prosthetic joint infections but results to a lot of complications including cellulitis, necrotizing fasciitis, myositis, myonecrosis, acute glomerulonephritis, pneumonia and Toxic Shock Syndrome. It is susceptible to beta-lactam antibiotics, but use of Penicillin monotherapy is associated with high mortality and extensive morbidity in the setting of aggressive infections associated with Toxic Shock Syndrome. Several observational studies demonstrated a clinical benefit with the addition of Clindamycin. However, even with prompt management, the reported mortality rate of toxic shock syndrome is from 30 to 70%.

Conclusion: Although Streptococcus pyogenes is only a rare cause of prosthetic joint infection, the potential severity of this infection and possibility of progression into Toxic Shock Syndrome warrants an immediate request for a synovial fluid culture to promptly start the appropriate therapeutic regimen.