Implementation of Outpatient Parenteral Antimicrobial Therapy (OPAT) in Patients with Complicated Periprosthetic Joint Infections.

Periprosthetic joint infections (PJI) are a serious complication of arthroplasty with high morbidity. With growing bacterial resistance and limited disposability of oral antibiotics with sufficient bioavailability, the need for intravenous antibiotic application is raising. This causes long-term hospital stays and rising costs. In the course of transferring procedures into an outpatient setting as well as coping with pressures on hospital capacity, outpatient parenteral antimicrobial therapy (OPAT) can build a bridge for the treatment of such infections.In a single centre analysis, 47 cases treated with OPAT were studied in relation to pathogen, antimicrobial resistance, indication for OPAT and follow up. Furthermore, the patients received an anonymised questionnaire with 4 clusters of interest in terms of internal quality assessment on the success and evaluation of this therapeutic procedure. Special attention was paid to the descriptive analysis of patients with periprosthetic joint infections (n = 30).Between May 2021 and October 2022 out of 47 patients with OPAT, 30 cases with periprosthetic joint infections were identified. For infected hip- and knee arthroplasties, a remarkable spectrum of pathogens was found. In hip infections highly resistant strains of Staphylococcus epidermidis and Enterococci were detected. In knee infections, the pathogens were more susceptible, but however highly virulent Staphylococcus aureus and Streptococci. Difficult to treat, mixed infections were found in both locations. The indication for OPAT was based in half of the cases on the high level of antimicrobial resistance, with availability of only parenteral applicable antibiotics. Further indications were mixed infections and difficult to treat pathogens, with flucloxacillin therapy as well as OPAT as the last therapeutic option. The questionnaire showed 96% patient satisfaction in terms of organisation and acceptance of this kind of therapy. Complications or unexpected outpatient/ hospital treatments were very rare in connection with OPAT. Two thirds of patients reported completion of the treatment. In the clinical follow up (average of 5.7 months), 96.6% of cases were declared free of infection. In one patient the infection persisted.OPAT is a safe and reliable therapeutic option for outpatients to continue parenteral antimicrobial treatment in joint infections. Due to increasing pressure on hospitals in terms of costs and capacity, this therapy offers an alternative to inpatient treatment. The indication for OPAT should be set individually, risk adjusted and not generalised for all patients. The outpatient sector needs financial and structural support for comprehensive roll-out of this treatment in Germany. A further focus should be on the prevention of periprosthetic joint infections. With the knowledge of the expected pathogens and the surgical resources, the standards should be adapted. The choice of the antibiotic should be specified and the intervals of application be shortened, according to the surgical course, in order to yield high levels of agent concentration in the surgical area. Further investigations are required to test the superiority of OPAT versus the oral administration of antibiotics in long-term observations as well as to define the necessary duration of OPAT.