The Cat Scratch That Leaves a Renal Mark: A Bartonell-Associated Glomerulonephritis

Introduction: Chronic infections such as infective endocarditis (IE) and infected implanted devices are known causes of glomerulonephritis (GN). Bartonella spp are a leading cause of blood culture-negative IE (BCNE). Due to this a high clinical suspicion is required to make the diagnosis. We present a case of Bartonella aortic graft infection related GN. Case Description: A 63-year-old man with a history of type A aortic dissection with graft repair, was undergoing treatment with cyclophosphamide, bortezomib, and dexamethasone for monoclonal gammopathy of renal significance induced C3 GN. After three months of therapy the patient developed sudden onset shortness of breath. A CT scan showed pseudoaneurysm at the suture line of his previous graft site. Subsequent PET CT scan was concerning for infection corresponding to the small pseudoaneurysm, but blood cultures were negative. TEE showed no vegetations on this prosthetic aortic valve. Bartonella henselae serology was positive with IgG >1:1024. His immunosuppression was discontinued and he was initiated on doxycycline 100mg BID and rifampin 300mg BID. Rifampin was discontinued due to poor tolerance. He developed shoulder pain and imaging showed increased size of pseudoaneurysm and surrounding hematoma needing immediate repair. During recovery, he had worsening renal function with creatinine rise from 1.2 mg/dL to 1.7 mg/dL; urine protein to creatinine (PCR) level was elevated at 1.2 mg/mg, and he had microscopic hematuria (>50 RBC/HPF). He underwent kidney biopsy which showed co-dominance of IgM, C3, and C1q with kappa staining. This led to diagnosis of Bartonella associated GN and he was initiated on rifabutin along with doxycycline, leading to reduction of PCR to 0.3 mg/mg and Cr to 1.37 mg/dL. Discussion: Bartonella IE and infected implanted devices, as seen in this case, may result in an infection related GN. Bartonella IE has been suggested to have clinicopathological differences from IE caused by other bacteria. This includes a higher frequency of crescents along with full-house staining patterns especially IgM and C1q. When diagnosis is uncertain following biopsy physicians should consider obtaining a targeted history of animal exposure and serological workup for Bartonella spp. especially in patients with a history of implanted devices or BCNE.