Microbiology of total knee arthroplasty

Objective: The aim of the study identify the common organism causing Prosthetic Joint Infection (PJI) and the drug resistance spectrum of the most common organisms causing PJI, to help in choosing appropriate antibiotics. Methods: The study was a retrospective study of the patients who received revision and re-revision of total knee arthroplasty for different reasons in our institution from August 2016 to August 2019. The isolated bacteria strains and drug-resistance rates for each pathogen for different antibiotics were presented. Results: There were 36 cases in the infectious group and 29 cases in the non-infectious group (PJI was diagnosed according to the diagnosing criteria from the Workgroup of the Musculoskeletal Infection Society). Of the 36 strains isolated, Gram-positive bacteria were the most common pathogenic organisms. Staphylococcus aureus (11, 39.28%) was the most common pathogen followed by Staphylococcus epidermidis (7, 25.00%) and Corynebacterium (5, 17.86%). Penicillin (86.11%), erythromycin (50.00%) and clindamycin (53.37%) showed high antibiotic resistance rate. In addition, the second-generation cephalosporins, usually as the prophylactic antibiotic, resistance rate was high (20%).Conclusion: This study provides some information on the most common organisms at our institution and the selection of antibiotics in the peri-operative period. Cefuroxime and clindamycin might not be appropriate for use as prophylactic antibiotics in revision total knee or hip arthroplasty. Vancomycin is ideal for empiric antibiotic use in suspected PJI cases because of the low drug-resistance rate.