A 46-year-old female with a history of rheumatoid arthritis, on methotrexate therapy, underwent a left total knee arthroplasty 4 years ago, and this recently became infected with MSSA about 1 year ago. The decision was made to have the patient undergo irrigation and debridement of the prosthesis, without removal of her underlying hardware. She was therefore given 6 weeks of IV cefazolin and oral rifampin, and then given 6 months of oral levofloxacin and rifampin (based on susceptibilities of her MSSA strain), after which she was transitioned to oral minocycline monotherapy for suppression.

Over the last few weeks however, she has been developing low-grade fevers of 99-100 F, along with joint pains involving her hands, elbows, knees and wrists; these are worse than her baseline joint pains from the RA.

In addition, she has now developed erythematous rashes on her arms and face after she goes outside for any prolonged period of time. Vitals are significant for mild tachycardia up to 101 bpm and a temperature of 99 F. Exam showed multiple erythematous, non-blistering rashes over her nose, cheeks, chin and across both wrists. There is a right ankle effusion present, and multiple tender joints.

Labs show a Hgb of 11.4 (which is near her baseline), WBC count of 9.1, and platelets of 155,000. Serum creatinine is 0.9 mg/dL, electrolytes and LFTs are WNL.

CH50 was low, and p-ANCA returned positive. MPO was negative. Aspiration of her prosthetic joint showed 1000 total nucleated cells with 35% neutrophils, cultures are still pending.

What is the best intervention for this patient?

A) Start IV piperacillin/tazobactam and vancomycin while awaiting joint culture results

B) Obtain blood cultures and start IV cefazolin again as you await joint culture results

C) Discontinue minocycline therapy, start hydroxychloroquine

D) Refer the patient back to Rheumatology (maybe they can figure out  what’s going on)