We sought to characterize the causative pathogens of prosthetic joint infections (PJIs), evaluate the trends in microbial etiologies, and identify potential risk factors for PJI. This was a retrospective study analyzing 70 patients with PJI following 3,253 total joint arthroplasties between 2011 and 2017. Staphylococci were the most common cause of infection (52.9%). There was a significant trend in the percentage of carbapenem-resistant gram-negative bacilli (GNB) (increased to 66.7% in 2016 from 0.0% in 2011) (p=0.021). GNB and polymicrobial etiology were found at significantly high levels in cases involving early PJIs (p=0.005 and p=0.048, respectively). While staphylococci were significantly higher in PJIs after total knee arthroplasty (75%), GNB were significantly higher in PJIs after total hip arthroplasty (49.1%) (p<0.001 and p=0.001, respectively). Binary logistic regression analysis showed that the risk of PJI was significantly higher in cases with fracture and diabetes mellitus (odds ratio [OR], 4.3, 95% confidence interval [CI], 1.78-10.5; OR, 4.1, 95% CI, 1.66-10.5, respectively). These results suggest that the empirical and targeted antimicrobial treatment of PJIs may become more difficult in the future.