Case Presentation: A 76-year-old female presented with generalized fatigue and purpuric rash over her left arm and both lower extremities. She also gives a history of cat bite 1 week back for which she did not seek any treatment. She noticed dark red urine but denies any fever, chills, burning micturition or cough. On examination she is afebrile and has normal vital signs. Physical exam shows the purpuric rash spread over her left arm and lower extremities. Bite marks are seen on left arm with no palpable lymphadenopathy. Labs show platelets: 11,000/uL, Hemoglobin: 8.3g/dL, creatinine: 1.4mg/dL, haptoglobin: <20mg/dL(low), LDH: 891U/L(increased), d-dimer:1.4uG/mL, Fibrinogen: 454mg/dL(increased). She was empirically treated with antibiotics but blood cultures were negative on 2 different occasions. Incubation for blood culture was 5 days on both these occasions. Peripheral smear showed schistocytes, malaria smear was negative and ADAMTS13 activity was less than 10%. A diagnosis of TTP was established and prednisone and plasmapheresis was started. Patient developed slurring of speech and MRI head showed bilateral embolic strokes in cerebral hemispheres. She was then started on rituximab and pulse dose methylprednisolone. Initial improvement was followed by further worsening of thrombocytopenia and encephalopathy requiring intubation. She was continued on daily plasmapheresis and rituximab therapy which eventually showed improvement in platelet count, hemoglobin and mental status. When her condition was more stable, she was transferred to her home town as her family wished to continue care in another hospital.
Discussion: We would like to highlight cat bite as a rare cause of TTP. More importantly, we had no evidence of C. canimorsus infection but the incubation technique used in this case was inappropriate for detecting this bacterium. We recommend that blood cultures should be drawn before starting anti-microbials and incubated for at least 14 days to adequately diagnose C. canimorsus infection in patients presenting with a cat or a dog bite.
Conclusions: We recommend that blood cultures should be drawn before starting anti-microbials and incubated for at least 14 days to adequately diagnose C. canimorsus infection in patients presenting with a cat or a dog bite. Obtaining an social history regarding pets is an important piece of information in patients presenting with TTP.