You think you know Cat Scratch Disease (CSD)? Think again. It’s not just a benign lymphadenopathy after a playful swipe from a kitten. In the shadows of this zoonotic infection lies a spectrum of atypical presentations that can mimic everything from viral encephalitis to culture-negative endocarditis. And if you're prepping for FRCPath Part 2, this is the kind of curveball that separates the good from the great.

Imagine this: a patient with culture-negative endocarditis, fever of unknown origin, and a history of cat exposure. Blood cultures are blank. Serology hints at Bartonella henselae. You reach for doxycycline, azithromycin, maybe rifampin. But here’s the kicker—none of them will kill the bug. Welcome to the paradox of Bartonella treatment: only aminoglycosides are bactericidal. Everything else? Just bacteriostatic passengers.

🧪 Does a Positive Catheter Tip Culture Confirm CLABSI? Understanding the Difference Between CRBSI and CLABSI