P30 A ‘cat’-astrophic case of Bartonella infective endocarditis causing a secondary cryoglobulinemia
Authors: Vivekanantham Arani , McCarthy Eoghan 
Published: April 2020

Abstract

Background
A 17-year-old college student presented with a year long history of weight loss and poor appetite. She had a background of pulmonary atresia with a ventricular septal defect, treated with a contegra conduit in childhood. She was initially treated for depression. Subsequently she developed a vasculitic rash on her legs with urinalysis demonstrating haemoproteinuria (urine PCR=116) resulting in renal referral and hospital admission. On examination, the patient had a BMI of 15 and was found to have massive splenomegaly.

Methods
Her initial creatinine was 128 (eGFR 58), although cystatin C (which accounts for low muscle mass) estimated her eGFR at 16. Renal biopsy showed focal necrotizing glomerulonephritis with no acute tubular necrosis or chronic change. Haematological work up was normal with bone marrow revealing reactive changes. Bloods revealed a weakly positive PR3 antibody and a provisional diagnosis of ANCA associated vasculitis was made for which prednisolone was commenced. A rheumatology review was sought. Review of systems was relevant for intermittent joint pains and ocular dryness. Additional bloods showed a low C4, positive RhF, negative anti-CCP, elevated immunoglobulins (IgG 45) and normal ENA profile.

Results
The provisional diagnosis was altered to cryoglobulinaemic vasculitis which was confirmed as a Type 3 cryoglobulin. Initial investigations for an infectious cause were negative however an echocardiogram showed vegetations on her conduit and treatment was commenced for endocarditis. Blood cultures were negative. Inflammatory markers failed to settle following two weeks of intravenous antibiotics and accordingly the patient was referred for surgical revision of her conduit. Tissue samples ultimately grew Bartonella and aspergillus species. Antibiotic therapy was altered to doxycycline and anti-fungal therapy whilst steroids were continued. Following completion of antibiotic treatment, she has had resolution of her cryoglobulinaemia, normalization of RhF/C4, creatinine is 58 with no proteinuria and IgG is 13.
The diagnosis was therefore confirmed as a Type 3 Cryoglobulinaemia secondary to Bartonella endocarditis +/- fungal infection of conduit. The patient’s mother revealed she had adopted several stray cats in the preceding year which was identified as the likely cause of the Bartonella infection.

Conclusion
In summary, this is a case of Bartonella endocarditis causing a secondary cryoglobulinemia; the exact mechanisms of this is not fully understood but is thought to be due to B cell hyperactivity. Culture-negative infective endocarditis constitutes approximately 10% of the total number of cases of infective endocarditis. Bartonella endocarditis is one of the most common causes of culture-negative endocarditis and is associated with a high mortality rate. Contact with animals, particularly cats, is a key risk factor. It is, therefore, important to enquire about such exposure especially when culture-negative endocarditis is suspected.

Disclosures
A. Vivekanantham None. E. McCarthy None.