Acute Deterioration of Patient with Sudden Onset of Shock Caused by Group G Streptococcus Infection after Revision Total Knee Arthroplasty: A Case Report

Background

Periprosthetic joint infection (PJI) represents one of the most major complications after total knee arthroplasty (TKA). Rates of PJI in primary TKA range between 0.5% and 1.9% and between 8% and 10% in revision TKA [1–3]. The incidence of PJI among patients with rheumatoid arthritis (RA) is 1.6 times greater than that among patients with osteoarthritis [4]. PJI is a challenging complication that usually progresses slowly with an appropriate combination of surgical and antibiotic treatments, without life-threatening complications. However, PJIs with rapid deterioration are rare, in which the sudden onset of septic shock rarely occurs. In the rare incidence, Streptococcus including the G strain were causatives [5].

Necrotizing fasciitis (NF) is a rare bacterial infection that spreads quickly throughout the body and can cause death. NF is commonly caused by group A Streptococcus. NF after TKA is extremely rare; the only reported case was a lifesaving above-knee amputation [6]. Here, we present a rare case of septic shock due to infection caused by group G Streptococcus after revision TKA. Successful treatment resulted in saving the infected limb as well as the life of a 61-year-old woman with RA treated with biological disease-modifying antirheumatic drugs (bDMARDs).

Case Report

A 61-year-old woman presented to our hospital with pain in her right knee. The patient received a diagnosis of PJI after revision TKA and was given intravenous antibiotic treatment at the previous hospital. The next day, she was referred to our hospital for treatment of septic shock. She had undergone primary TKA (Sigma RP-F, Depuy, Warsaw, IN, USA) for rheumatoid arthritis 10 years previously and revision TKA (P. F. C Sigma TC3, Depuy, Warsaw, IN, USA) due to aseptic loosening 6 months previously. The patient had been receiving oral prednisone (4 mg daily), tacrolimus (1.5 mg daily), and etanercept (50 mg subcutaneous injections weekly). Pain, swelling, and burning sensations were observed in the right knee, and redness and local heat extending to the right lower leg were observed during physical examination. Laboratory examination showed a white blood cell count of 8.1×109/L and C-reactive protein level of 19.9 mg/L. We performed aspiration of the right knee joint, and gram-positive streptococci were detected by staining, which were later identified to be Streptococcus dysgalactiae (group G Streptococcus). She had a temperature of 38.2°C, heart rate of 128 beats/min, and blood pressure of 56/32 mmHg. Laboratory investigations yielded the following values: hemoglobin, 9.5 g/dL; serumglucose, 99 mg/dL; serum creatinine, 2.93 mg/dL; and sodium, 139 mEq/L. Radiography of the right knee showed no osteolytic lesions and no signs of periprosthetic loosening (Figure 1). A computed tomography scan might have helped with the diagnosis but was not performed because it was too dangerous to move the patient, who was in a state of shock, to the examination room. We diagnosed septic shock due to PJI after revision TKA and rapidly performed irrigation, debridement, polyethylene liner exchange, and antibiotic therapy because there were no findings that suggested loosening of the prosthesis and because of the short period of time since the onset of symptoms. During the surgery, a lack of tissue resistance to blunt finger dissection was observed. The patient was rapidly admitted to the Intensive Care Unit for mechanical ventilation after the operation. She was immediately placed empirically on meropenem (1.0 g every 12 h), vancomycin (0.5 g every 12 h), and clindamycin (600 mg every 8 h). We administered continuous hemodiafiltration and started her on nor-adrenaline via a peripheral intravenous catheter. Blood culture tests were performed several times, but the results were all negative. The patient’s clinical condition gradually stabilized, and noradrenaline application was stopped on day 5 of admission. However, on the hospitalization day 8, swelling and burning sensation were again observed in the right knee, and approximately 35 mL of exudate was aspirated. Analysis of the joint aspiration revealed a white blood cell count of 60 100/ μL and a positive alpha-defensin test. We judged eradication failure of the infection and performed irrigation, debridement, implant removal, and antibiotic spacer (1 g of vancomycin per 40 g of cement) placement (Figure 2). The patient’s postoperative period was uneventful. Six weeks after surgery, the inflammatory markers had normalized (C-reactive protein, 0.05 mg/L) with intravenous antibiotic therapy (ampicillin 2 g every 6 h and clindamycin 600 mg every 8 h for 2 weeks and then cefazolin 2 g every 8 h for 4 weeks). Ten weeks after surgery, the patient displayed no clinical signs of infection and was discharged from the hospital with 2 canes. Based on the suggestion of the Department of Rheumatology and Clinical Immunology, she was started on bucillamine (100 mg daily) 1 month after surgery, and the dose was gradually increased to 300 mg daily. At the time of discharge, she was taking busiramine and prednisolone (4 mg daily). We did not resume bDMARDs because her RA was well controlled. She was administrated oral cefalexin 500 mg 3 times a day for 2 months.

Approximately 1.5 years after surgery, she underwent re-revision TKA (NexGen Rotating Hinge Knee, Zimmer-Biomet, Warsaw, IN, USA; Figure 3). Throughout the follow-up period, inflammatory markers were not elevated and no clinical signs of infection were observed. One year after the final surgery, the patient walked with a cane and had no symptoms of infection. No pain, swelling, or burning sensation was observed in the right knee, and right knee motion ranged from 0° of extension to 90° of flexion with no extension lag.

Discussion

Significant advances in RA treatment have resulted in the introduction of bDMARDs, such as tumor necrosis factor inhibitors (TNFi). Nevertheless, patients with RA still progress to end-stage arthritis and require arthroplasty [7]. Critical outcomes, such as infection and dislocation, were reported to be higher in patients with RA than in those with osteoarthritis. Lee et al reported that the deep infection rate was significantly higher in RA patients than in osteoarthritis patients (3.0% vs 0.9%, P<0.001) [8]. Rene et al reported that patients with RA had an increased risk of PJI (HR: 1.46; 95% CI: 1.13–1.88) and death (HR: 1.25; 95% CI: 1.01–1.55) [9]. Hayashi et al reported that TNFi therapy was found to be significantly associated with the development of late infection after total hip arthroplasty (OR: 11.7; 95% CI: 1.2–109) [10]. In the present case report, RA treated with bDMARDs led to an immunocompromised condition, which might be the reason for this severe infection.

Beta-hemolytic streptococcus can cause PJI; however, Cunningham et al reported that Staphylococcus species such as coagulase-negative staphylococci, methicillin-sensitive Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus represented the largest proportion of infecting organisms, whereas gram-negative organisms and fungi were relatively less prevalent [11]. It was reported that 7% to 12% of PJI are caused by Streptococcus spp. [12,13]. Group C and G streptococcal bacteremias are linked to diabetes mellitus, cardiovascular disease, malignancy, immunosuppression, and breakdown of the skin [14]. Patients infected with group C and G streptococcus presented with septic arthritis more often than those infected with Group B, whereas patients with group A infections had abscesses involving sites deeper than the skin more often than patients with group C and G infections [15]. These reports suggest that immunosuppressed patients with RA, as in the present case, are more susceptible to group C and G streptococcus and are at a higher risk of PJI.

NF is an uncommon, life-threatening, and aggressive soft-tissue infection. NF occurring simultaneously with PJI is a rare occurrence. Hanno et al reported the only case, which was of a 65-year-old woman with NF following TKA who was infected with Staphylococcus epidermidis and underwent above-knee amputation [6]. Establishing a diagnosis of NF is challenging, and the Laboratory Risk Indicator for Necrotizing Fasciitis (LRINEC) score is a diagnostic tool. In the present case, the LRINEC score was 8 points, and a score ≥8 was strongly predictive of NF [16]. However, their study showed a probability of necrotizing infections of 75% corresponds to a score of 8. Neeki et al reported a false positive rate for the LRINEC score of 10.7% [17]. Therefore, we need to understand the limitations of the LRINEC score. Because no obvious necrotic tissue was observed intraoperatively, debridement of the lower leg was not performed. In addition, when signs of infection were observed again, we were able to respond rapidly, which saved the patient’s life and preserved her lower leg.

Conclusions

We encountered a rare case of PJI in an immunosuppressed RA patient whose clinical course rapidly worsened, with sudden onset of septic shock caused by group G Streptococcus. Appropriate and prompt surgical treatment and intensive care made it possible to save the affected knee joint as well as the patient’s life.