BackgroundIn the context of an increase number of primary and revision total hip and total knee arthroplasty performed yearly, an increased risk of complication is expected. Prosthetic joint infection (PJI) remains the most common and feared arthroplasty complication. Ralstonia pickettii is a Gram-negative bacterium, that has also been identified in biofilms. It remains an extremely rare cause of PJI. There is no report of an identification of R. pickettii on an extracted spacer loaded with antibiotic.Case presentationWe present the case of an 83-years-old Caucasian male patient, that underwent a right cemented total hip replacement surgery. The patient is diagnosed with an early PJI with no isolated microorganism. A debridement and change of mobile parts is performed. At the beginning of 2016, the patient in readmitted into the Orthopedic Department for sever, right abdominal and groin pain and elevated serum erythrocyte sedimentation rate and C-reactive protein. A joint aspiration is performed with a negative microbiological examination. A two-stage exchange with long interval management is adopted, and a preformed spacer loaded with gentamicin was implanted. In July 2016, based on the proinflammatory markers evolution, a shift a three-stage exchange strategy is decided. In September 2016, a debridement, and changing of the preformed spacer loaded with gentamicin with another was carried out. Bacteriological examination of the tissues sampled intraoperatively was positive for Pseudomonas aeruginosa. From the sonication fluid, no bacteria were isolated on culture or identified using the bbFISH assay. During the hospitalization period, the patient received i.v. ceftazidime 3x2g/day and p.o. ciprofloxacin 2x750mg/day, antibiotic therapy that was continued after discharge with p.o. ciprofloxacin 2x750mg/day for 6 weeks. In February 2017, a reimplantation of a revision prosthesis is performed. The retrieved spacer is sonicated, and after 4 days of incubation of the sonication fluid, R. pickettii is isolated. A long term antibiotic therapy with cotrimoxazole being prescribed.ConclusionsBacteria culture of sonication fluid remains the gold standard in diagnosing prosthetic joint infections. R. pickettii remains an extremely rare cause of prosthetic joint infection. Optimal management of R. pickettii prosthetic joint infections of has not been established.

By 2030, the annual number of combined total hip and knee arthroplasty is estimated to reach 3.5 to 4 million in the US alone. In the context of a constant increase of the number of primary and revision total hip and knee arthroplasty, an increased risk of complication is expected. Prosthetic joint infections (PJIs) represent major cause of healthcare expenditure and morbidity. PJI still remain the most common and feared arthroplasty complication. A rapid and correct diagnosis of infection is decisive for a correct therapeutical management. In this setting, the Academic Emergency Hospital Sibiu adopted and implemented, with the beginning of September 2016, a new strategy for the diagnosis of PJIs strategy that uses sonication and beacon-based fluorescent in situ hybridization (bbFISH) technology. Until November 2017, 40 patients (40 retrieved implants) were enrolled in the study. Sonication fluid (SF) was collected after sonication of the implants, and samples were harvested on aerobic and anaerobic culture media. A bbFISH was used as a rapid method of bacteria detection. 16 patients were diagnosed with PJIs (all 16 patients presented a positive culture of the SF). Comparing bbFISH with culture, 11 samples tested true-positive. As the kit doesn’t contain probes for Pseudomonas fluorescens or Ralstonia pickettii , 4 strains of R pickettii and 1 strain of P fluorescens that was associated with Staphylococcus epidermidis were not detected. Bacteria culture of SF remains the gold standard. bbFISH holds promise to be a diagnostic tool for rapid identifying of PJIs. The bbFISH assay needs to be optimized for the detection of bacterial strains that are relevant for the PJIs field.

Background Periprosthetic joint infections (PJIs) represent one of the most serious complications associated with joint replacement surgeries, a complication also of modern orthopedic surgery despite the efforts that occurred in this field. Frequently PJIs lead to prolonged morbidity, increased costs and mortality. Methods We are conducting a single-center observational cohort ongoing study in the Academic Emergency Hospital Sibiu, Romania, study in which sonication of the retrieved and as a rapid method of bacteria detection, molecular identification of bacteria by 16S rRNA beacon-based fluorescent in situ hybridization (bbFISH) are used. Results A total of 61 patients were enrolled in this study. The diagnosis of aseptic loosening was established in 30 cases (49.1%) and the diagnosis of periprosthetic joint infection was established at 31 patients (50.8%). The mean follow-up period in the subgroup of patients diagnosed with periprosthetic joint infections was 36.06 ± 12.59 months (range: 1–54). The 25-months Kaplan-Meier survival rate as the end point, as a consequence of the period of enrollment and a different follow-up period for each type of surgical procedure, was 75% after debridement and implant retention, 91.7% after one-stage exchange, 92.3% after two-stage exchange, and 100% after three-stage exchange. There were no significant differences in survival percentage. Conclusions Our study has good results similar to previously published data. We cannot recommend one strategy of managing prosthetic joint infections over the other. Definitely, there is a need for prospective randomized controlled trials.