353 - Starry Night, Starry Bright, A Lil’ Doxy Will Help You See the Light

Background: Bartonella henselae neuroretinitis (BHNR) is a rare complication of cat scratch disease (CSD) occurring in 1-2% of cases. BHNR requires prompt diagnosis and treatment to prevent potential vision loss. Doxycycline, in combination with rifampin, is consider the treatment of choice. Empiric therapy is often started based on clinical suspicion prior to serologic confirmation. We present a case of BHNR requiring doxycycline graded challenge.

Methods: We report a case of a 45-year-old female with a past history of multiple sclerosis treated with natalizumab presenting with acute right-sided vision loss. She reported suffering a cat scratch 6 weeks prior and had noteworthy tick exposure. She was admitted to our hospital for progressively worsening vision loss. MRI brain demonstrated right-sided enhancement consistent with retinitis. Ophthalmology exam suggestive of infectious papillitis, neuroretinitis, and granulomatous inflammation.

Results: Infectious diseases (ID) was consulted with concern for BHNR and a history of a severe tetracycline allergy, throat swelling age 17. Given declining vision and a differential including both Lyme disease and BHNR, the decision was made to empirically treat with doxycycline while awaiting serologic studies. She successfully underwent doxycycline graded challenge (10mg administered IV followed by 100mg administered IV one hour later) and ultimately completed a 6-week course of doxycycline in combination with 2 weeks of rifampin followed by 4 weeks of azithromycin. Bartonella serologies returned positive 1:256 and her Lyme screen was negative. At her 6-week follow up, her vision had significantly improved but not yet returned to baseline.Retina images
Visual field testing


Conclusion: Doxycycline serves as a treatment of choice for BHNR; however, our patient reported a severe, likely IgE-mediated reaction to tetracycline 28 years prior. She subsequently tolerated the first doxycycline graded challenge at our institution. Unlike B-lactam allergies, there is a paucity of literature exploring the cross-reaction potentials of various tetracyclines. Limited evidence has suggested that cross-reactions are not absolute. Tetracycline allergies present an opportunity for antimicrobial stewardship.