Take-Home Points
- History and physical examination are key in identifying possible etiologies of orthopedic infections.
- If identified in the acute setting, periprosthetic infections can successfully be treated with irrigation, débridement, and polyethylene liner exchange.
- Discussion with an interdisciplinary medical team, including infectious disease specialists, can aide in improved diagnosis and treatment of periprosthetic infections.
Periprosthetic infection is a leading cause of morbidity after total joint arthroplasty.1 Despite advances in modern surgical practices, infection rates continue to range from 1% to 3% among all arthroplasty procedures performed in the United States.2-5 The most common causes of periprosthetic infection include Staphylococcus aureus, streptococcus, enterococcus, Escherichia coli, and Pseudomonas aeruginosa.6 However, many other pathogens that cause periprosthetic infection should be considered in the clinical setting. In this case report, periprosthetic knee infection with P shigelloides occurred after consumption of raw oysters.
P shigelloides is a gram-negative facultative anaerobic organism in the Vibrionaceae family,7 which also includes Vibrio vulnificus and Vibrio parahaemolyticus. P shigelloides is most well-known for causing diarrhea and septicemia in people who have consumed raw oysters or shellfish in the United States.8,9 Although P shigelloides infection is rare, there have been clinically significant outbreaks from contaminated water in Japan,10 consumption of freshwater fish in the Democratic Republic of the Congo,11 and consumption of raw oysters in the United States.8,9 Children and immunosuppressed people are most susceptible to the disease, which most commonly manifests as self-limiting watery diarrhea, with septicemia only in advanced cases.12There are very few reports of P shigelloides in the orthopedic population. In the medical literature, we found only 1 case of septic arthritis in a native knee; disease progression resulted in the patient’s death.13In this article, we report a case of P shigelloides septicemia that caused periprosthetic knee infection in a chemically and biologically immunosuppressed patient. The patient provided written informed consent for print and electronic publication of this case report.
Case Report
Out of concern about a periprosthetic knee infection, a 66-year-old man was transferred from a regional medical center to our tertiary referral center. The patient reported a 3-day history of significant knee pain, swelling, and erythema that started the day after he consumed raw oysters at a seafood bar. He was unable to bear weight on the right knee and remained at home 1 day before presenting to the regional medical center.
The patient had undergone elective right total knee arthroplasty 18 months earlier, without previous issue (Figures A, B), and had a medical history of type 2 diabetes mellitus, psoriatic arthritis, hypertension, hyperlipidemia, hypothyroidism, and benign prostatic hypertrophy.
On presentation to our facility, the patient described pain in the right knee. Physical examination revealed swelling and erythema of the knee. Vital signs were within normal limits, with a temperature of 98.5°F. Laboratory work-up revealed white blood cell count of 17,700 with 79% neutrophils and 9% lymphocytes, serum C-reactive protein level of 270 mg/L, and erythrocyte sedimentation rate of 46 mm/h. Aspiration of the knee yielded about 100 mL of thick, brownish synovial fluid. Gram stain of the knee aspirate revealed gram-negative rods and many white blood cells. Nucleated cell count of the aspirate was 22,400 with 88% neutrophils. Blood cultures were obtained, and broad-spectrum antibiotics (vancomycin and ceftriaxone) were started in preparation for surgery.
Within 24 hours, the patient was taken for irrigation and débridement with polyethylene exchange of the right knee. Surgical exploration revealed brownish purulent fluid in the knee. The polyethylene insert was removed, and a complete synovectomy was performed for knee débridement. Nine liters of triple antibiotic (utilized bacitracin, polymyxin, and gentamicin) saline were used to copiously clean the metal surfaces of the implant, and a new polyethylene liner was inserted. Absorbable calcium sulfate antimicrobial beads, stimulant beads with 1 gram of vancomycin and 1.2 grams of tobramycin, were implanted both inside and over the knee capsule during closure.
Blood cultures, knee aspirate, and surgical cultures were all positive for P shigelloides. Of note, the patient did not describe having diarrhea, a symptom common in P shigelloides infection. After final cultures were received, the patient was placed on intravenous ceftriaxone and oral levofloxacin for 6 weeks. Three months later, he reported full return to activity and clearance of the infection.
Discussion
This case is a reminder that periprosthetic knee infection can occur from a variety of pathologic organisms and that obtaining a complete history is an important part of any diagnostic work-up. Although P shigelloides infection is rare, our patient had important historical findings that led to suspicion of Vibrionaceae infection: recent consumption of raw oysters, immunosuppression with etanercept and prednisone for psoriatic arthritis, and diabetes with hemoglobin A1c of 9.9% and presenting blood sugar of 338 mg/dL. His positive blood cultures represented P shigelloides septicemia, which seeded the knee prosthesis and led to acute periprosthetic infection. To our knowledge, this is the first report of P shigelloides periprosthetic infection in the orthopedic literature. The only other reported case of P shigelloides septicemia leading to septic arthritis in a native knee occurred in a 68-year-old Australian man who had end-stage liver disease and eventually died from complications of the P shigelloides infection.13