Recognizing Bartonella as a Cause of Glomerulonephritis Without Obvious Endocarditis

Introduction: Rapidly Progressive Glomerulonephritis (RPGN) is a condition characterized by rapid deterioration of kidney function along with features of nephritic syndrome. It can have a broad differential diagnosis including multiple autoimmune disorders and a variety of infections. While infective endocarditis often causes acute renal failure due to glomerulonephritis, diagnosing it can be challenging without clear clinical signs. Bartonella is a common cause of culture-negative endocarditis and patients can present with an acute kidney injury (AKI) due to underlying glomerulonephritis. Case Description: A 72-year-old male with a history of bicuspid aortic valve (post-TAVR) and prior MCA stroke (post-thrombectomy) was transferred to our center for an AKI requiring dialysis. He initially presented with weakness and swelling but no other symptoms. A renal biopsy showed crescentic glomerulonephritis. Testing for common autoimmune and infectious causes were negative, thus causing a diagnostic challenge. However, after a detailed social history revealed that the patient owned 12 cats, we were prompted to obtain Bartonella serologies, which returned positive. Blood cultures were consistently negative, and a Transthoracic and Transesophageal Echocardiogram ruled out vegetations. Treatment with doxycycline and rifampin was started after which a marked improvement in kidney function was seen. Discussion: Infective endocarditis (IE) is a known cause of AKI due to glomerulonephritis, but Bartonella-induced IE can be difficult to identify, often lacking vegetations or positive blood cultures. As a leading cause of culture-negative endocarditis, Bartonella should be considered in cases of unexplained RPGN, especially when other causes are ruled out. Bartonella henselae is commonly linked to cat exposure; 40–50% of cats are carriers, with higher rates in multi-cat households. In this case, a thorough social history led to Bartonella testing and diagnosis. Bartonella-associated glomerulonephritis typically responds well to doxycycline and rifampin, which target its intracellular persistence. Unlike other forms of crescentic GN, Bartonella-related RPGN often has a more favorable prognosis. This patient’s renal function improved markedly with treatment, highlighting the importance of early detection and targeted therapy.