Aims: Management of periprosthetic joint infection (PJI) after total knee arthroplasty (TKA) is challenging. Antibiotic management remains elusive due to differences in epidemiology and resistance between countries and reports. Before the efficacy of surgical treatment options is investigated, it is crucial to investigate the bacterial strains causing PJI, especially for cases where a culture could not be obtained.

Patients and Methods: A review of all revision TKAs between 2006 and 2018 in a tertiary referral center was performed. Included were cases meeting the consensus criteria for PJI, with identified cultures. Using a cluster analysis, 3 chronological time periods were created. We then evaluated antibiotic resistance of identified bacteria between these 3 clusters and the effectiveness of our antibiotic regime.

Results

We identified 129 PJI with 161 culture identified bacteria. Coagulase-negative Staphylococci (CNS) were diagnosed in 46.6% cultures, followed by Staphylococcus aureus in 19.8% of cultures. Overall antibiotic resistance (p=0.454) has not increased during the study period. CNS resistance to teicoplanin (p<0.001), fosfomycin (p=0.016) and tetracycline (p=0.014) has increased. Vancomycin had an 84.4% overall sensitivity and 100% CNS sensitivity and was the most effective agent.

Conclusion

Although we were unable to show an overall increase in antibiotic resistance in organisms that cause PJI after TKA during the study period, this was not true for CNS. It is concerning to note that when specifically looking at CNS resistance to new antibiotics, but not vancomycin, it has increased in little more than a decade. This study suggests that referral centres should continuously monitor obtained cultures as this has significant implications for both prophylactic treatment in primary as well as empirical antibiotic treatment in PJI.