Periprosthetic joint infection (PJI) is a rare but devastating complication of total joint arthroplasty. Identifying the offending infectious agent is essential to appropriate treatment, and uncommon pathogens often lead to a diagnostic delay. This case describes the first known instance of a total knee arthroplasty (TKA) with Rothia mucilaginosa, a typical respiratory tract organism. This report aims to provide insight into the treatment of this atypical PJI, as there are only six previously published cases of Rothia species PJI septic arthritis. The patient is a 64-year-old diabetic male who underwent a right TKA and left TKA ∼6 months later. Approximately 3 weeks status post-left TKA, he showed evidence of left PJI. One year after treatment and recovery from his left PJI, he presented with several months of right knee pain and fatigue. Subsequent labs and imaging revealed right PJI. No recent history of dental disease or work was observed. He then underwent two-stage revision right knee arthroplasty and microbial cultures yielded Rothia mucilaginosa. After initial empiric treatment, antibiotic therapy was narrowed to 6 weeks of vancomycin. Following negative aspiration cultures the patient underwent reimplantation of right TKA components. One year following treatment, the patient was fully recovered with no evidence of infection. This case emphasizes the possibility of microbial persistence despite various antibiotic treatment regimens for the patient’s contralateral knee arthroplasty and PJI. Additionally, this case demonstrates the importance of two-stage revision in patients with PJI, and the viability of treating Rothia species PJIs with vancomycin.
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