Case Presentation: A 72-year-old male with a past medical history of osteoarthritis presented to the emergency department with complaints of fever and chills for 3 days. She received glucocorticoid injection for left knee pain a few days prior to presentation. Her initial vitals were a heart rate of 122 bpm, blood pressure was 147/77 mmHg, respiratory rate was 22, the temperature was 38.1C, she was saturating 94 % on room air. Physical exam revealed a normal exam except for bilateral conjunctival injection. Laboratory results white cell count of 7 K/µL, hemoglobin of 13.7 g/dL, low platelet count of 41 K/µL with an unknown baseline, low sodium of 127 mmol/L, high creatinine of 1.73 mg/dl, high lactate of 3.4 mmol/L, creatinine phosphokinase (CPK) of 1873 unit/L which increased to 6811 unit/L the next day. The patient also had elevated liver function tests- ALT of 47 unit/L, total bilirubin of 1.3 mg/dL, AST of 99 unit/L. Urinalysis revealed 5-9/hpf RBCs. She recalled a remote history of tick bite two months prior. With a high suspicion for tick-borne illness, she was started on doxycycline as well as broad-spectrum antibiotics for possible septic arthritis. Infectious disease (ID) department was consulted. Various serologic testing- Anaplasma, Babesia, Ehrlichia IgG, and IgM antibodies were negative along with Leptospira IgM, which was ordered since she had the bilateral conjunctival injection. Her board spectrum antibiotics were discontinued once septic arthritis was ruled out; she was continued on doxycycline and received minimal intravenous fluids for the rhabdomyolysis. Her peripheral smear was negative for blood parasites, intra or extraerythrocytic or intraleukocytic inclusion organisms. ID recommended a malaria smear to rule out Babesia which can co-infect with Anaplasmosis; however, it was negative. She responded well to doxycycline, her rhabdomyolysis/acute kidney injury resolved and her sodium along with platelet count was normal on the day of discharge. She improved symptomatically and was discharged home. PCR was positive for Anaplasma and negative for Ehrlichia thereby confirming the diagnosis.
Discussion: The exact etiology of rhabdomyolysis and subsequent renal failure associated with Anaplasma infection is unknown, although the elevation of cytokine-induced skeletal muscle damage has been proposed. Treatment should be initiated promptly without waiting for laboratory diagnosis such as IgG/IgM antibodies, peripheral smear testing. PCR is the test of choice and should be used to confirm serology if they are positive.
Conclusions: Rhabdomyolysis and subsequent renal failure is a rare complication of anaplasmosis. Checking CPK is warranted in any patient who presents with this infection.