Title : Ralstonia pickettii periprosthetic joint infection
Abstract:
Background: Periprosthetic joint infection (PJI) is the most common and feared arthroplasty complication. Ralstonia pickettii is an opportunistic Gram-negative bacterium, causing nosocomial infections in immunocompromised patients. It is an environmental bacterium that has been also identified in biofilms. However, it remains an extremely rare cause of PJI. We report a case of Ralstonia pickettii PJI following total hip arthroplasty.
Case description: We present the case of a 62-years-old male patient, that underwent a left cemented total hip replacement surgery. Four weeks later, the patient presented with fever and groin pain. Laboratory findings showed hyperleukocytosis and elevated C-reactive protein (CRP). Blood cultures were performed. Radiograph of the pelvis and a horizontal beam lateral hip radiograph of the left hip revealed signs of loosening at the level of both the acetabular and femoral components. An early PJI was diagnosed. An ultrasound guided joint aspiration was performed with a negative microbiological examination. Debridement and change of mobile parts with the retention of fixed prosthetic components were performed. Soft tissues surrounding the implant and periprosthetic interface membrane were taken for microbiological testing. Post-operatively, the patient received empiric intravenous antibiotic therapy based on cefotaxime 150 mg/kg/day and vancomycin 40 mg/kg/day after a loading dose of 15 mg/kg. Evolution was marked by a persistent fever and high CRP. Bacteriological examination of the tissues sampled intraoperatively was negative. The retrieved mobile parts were sonicated. Ralstonia pickettii was isolated from the sonication fluid culture after 8 days of incubation and from blood cultures after 10 days of incubation. The isolated strain was sensitive to imipenem, meropenem, ciprofloxacin and cotrimoxazole. A long-term antibiotic therapy was prescribed based on intravenous imipenem and per os ciprofloxacin (750 mg bid) for 2 weeks followed by 10 weeks of oral ciprofloxacin monotherapy. The clinical and biological evolution was favourable.
Conclusions: R. pickettii remains an extremely rare cause of PJI. Bacteria culture of sonication fluid remains the gold standard in PJI diagnosing. However, when an opportunistic pathogen of low virulence such as Ralstonia is isolated, differentiating contaminant from true pathogen must be based on the clinical context. Optimal management of R. pickettii PJI has not been established.
