Case Presentation: A 58-year-old male with HIV and an absolute CD4 count of 400 cells/microL presented with acute onset of mental status changes. Patient presented with a week of fever, increased lethargy, and confusion. He was oriented only to person but the remainder of neurological exam was unremarkable. CT head was unremarkable and MRI brain was negative for masses, abnormal enhancement, or acute infarcts. Initial infectious workup included blood cultures, RPR, CMV serology and PCR, Toxoplasma gondii serology and PCR, HSV1 and HSV2 PCR, VZV PCR, COVID19 PCR, and Interferon-gamma release assay– all of which returned negative. Lumbar puncture was performed and was significant for elevated protein, decreased glucose, and an elevated nucleated cell count with lymphocytic predominance. Patient was treated empirically for meningoencephalitis with broad spectrum antibiotics and antivirals. Additional infectious studies from CSF were largely unrevealing. Upon further questioning, patient endorsed cat ownership and thus Bartonella henselae serologic testing was performed and returned positive with an IgM titer of >1:20. Retrospective attempts to amplify Bartonella DNA from the CSF were unsuccessful. Antibiotics were tailored to doxycycline and rifampin for a total course of twenty-one days to treat a presumptive case of neurobartonellosis. The patient experienced clinical improvement and had returned to baseline mental status at subsequent follow up appointments.
Discussion: Bartonella henselae is a gram negative bacillus that is the causative agent of cat scratch disease; a clinical syndrome characterized by regionalized lymphadenopathy and fever. However, since it was discovered in 1950, B. henselae has been associated with many other clinical syndromes. Although rare, B. henselae has been reported to cause neurologic syndromes in ~2% of infected patients. Cat exposure is a risk factor for acquiring bartonellosis and pet ownership should always be queried during an infectious work up. Unfortunately, there is no single diagnostic technique that has been proven superior to confirm the presence of B. henselae. Isolation of Bartonella species in a culture requires a long incubation period thus serology and PCR are the preferred methods of testing. Though, it has been shown that the sensitivity of the PCR is variable and ranges from 43-76%. Additionally, several cases of neurobartonellosis have been reported with positive serologic testing and negative PCR. Identification of neurologic syndromes caused by B. henselae can be challenging and ultimately clinicians should consider epidemiological and clinical components as well as laboratory tests in making the diagnosis. There is little evidence reported in the literature regarding treatment of neurobartonellosis; however, the expert consensus would recommend a combination of doxycycline and rifampin for 10 to 14 days. If correctly identified and treated, the prognosis for encephalopathy caused by B. henselae infection is excellent, with most patients having complete resolution of symptoms after completion of treatment.
Conclusions: We present a case of meningoencephalitis in an HIV patient associated with cat ownership and Bartonella henselae infection. Consideration of B. henselae as a cause of infectious encephalitis in an immunocompromised host is essential for proper management of this uncommon condition.