A 55-Year-Old Male Presenting With Altered Mental Status: A Complicated Case of Intracranial Aneurysm

Clinicopathological differences between Bartonella and other bacterial endocarditis-related glomerulonephritis - our experience and a pooled analysis

Background

Although Staphylococcus aureus is the leading cause of acute infective endocarditis (IE) in adults, Bartonella spp. has concomitantly emerged as the leading cause of "blood culture-negative IE" (BCNE). Pre-disposing factors, clinical presentation and kidney biopsy findings in Bartonella IE-associated glomerulonephritis (GN) show subtle differences and some unique features relative to other bacterial infection-related GNs. We highlight these features along with key diagnostic clues and management approach in Bartonella IE-associated GN.

Methods

We conducted a pooled analysis of 89 cases of Bartonella IE-associated GN (54 published case reports and case series; 18 published conference abstracts identified using an English literature search of several commonly used literature search modalities); and four unpublished cases from our institution.

Results

Bartonella henselae and Bartonella quintana are the most commonly implicated species causing IE in humans. Subacute presentation, affecting damaged native and/or prosthetic heart valves, high titer anti-neutrophil cytoplasmic antibodies (ANCA), mainly proteinase-3 (PR-3) specificity, fastidious nature and lack of positive blood cultures of these Gram-negative bacilli, a higher frequency of focal glomerular crescents compared to other bacterial infection-related GNs are some of the salient features of Bartonella IE-associated GN. C3-dominant, but frequent C1q and IgM immunofluorescence staining is seen on biopsy. A "full-house" immunofluorescence staining pattern is also described but can be seen in IE -associated GN due to other bacteria as well. Non-specific generalized symptoms, cytopenia, heart failure and other organ damage due to embolic phenomena are the highlights on clinical presentation needing a multi-disciplinary approach for management. Awareness of the updated modified Duke criteria for IE, a high index of suspicion for underlying infection despite negative microbiologic cultures, history of exposure to animals, particularly infected cats, and use of send-out serologic tests for Bartonella spp. early in the course of management can help in early diagnosis and initiation of appropriate treatment.

Conclusion

Diagnosis of IE-associated GN can be challenging particularly with BCNE. The number of Bartonella IE-associated GN cases in a single institution tends to be less than IE due to gram positive cocci, however Bartonella is currently the leading cause of BCNE. We provide a much-needed discussion on this topic.

Bartonella Endocarditis Presenting as Recurrent Cerebral Mycotic Aneurysm

Bartonella henselae is a known cause of culture-negative endocarditis, which can be difficult to diagnose without a high clinical suspicion as specific diagnostic testing is required. 

We report the case of a 48-year-old male who presented with altered sensorium. A CT of the head showed left-hemispheric intracranial hemorrhage (ICH) likely secondary to ruptured left posterior cerebral artery (PCA) fusiform aneurysm seen on catheter cerebral angiogram, which was treated with endovascular embolization. The patient had a significant history of mitral valve prolapse; however, a transthoracic echocardiogram (TTE) was negative for any vegetation. Blood cultures were also negative. A year later, he presented with another ICH in the PCA territory and was found to have a new left distal PCA aneurysm, which was again treated with endovascular embolization. During that hospitalization, an echocardiogram showed myxomatous changes in the mitral valve with severe mitral regurgitation; however, blood cultures were negative. Further queries about the patient’s social history revealed that his spouse had been a cat owner in 2018, which prompted Bartonella henselae testing. The blood work showed elevated immunoglobulin G (IgG) titers for which he was placed on antibiotics. A follow-up catheter angiogram detected a new distal middle cerebral artery (MCA) M4 branch aneurysm treated with surgical clipping. The aneurysm tested positive for Bartonella henselae on polymerase chain reaction (PCR) testing. The patient subsequently underwent successful mitral valve replacement, which also was positive for Bartonella henselae on PCR testing; however, the Warthin-Starry stain was negative.

This case demonstrates how a comprehensive history along with persistent evaluation for the underlying etiology of cerebral aneurysms can lead to the diagnosis of Bartonella henselae endocarditis. Cerebral mycotic aneurysms are known complications of endocarditis; however, the underlying infection can be difficult to diagnose. Recognition of this culture-negative endocarditis is critical for the appropriate treatment and management of patients to prevent morbidity and mortality.