Summary

Chronic Q fever, caused by Coxiella burnetii, is a persistent infection that primarily affects individuals with underlying valvular or vascular abnormalities. The standard treatment regimen consists of prolonged dual therapy with doxycycline and hydroxychloroquine, typically administered for a minimum of 18 months [1]. This combination targets both the intracellular pathogen and the acidic vacuolar environment in which it resides. A key indicator of therapeutic response is the progressive decline in phase I IgG antibody titers, which is generally observed within the first few months of treatment [2].

However, in rare instances, antibody titers may remain persistently elevated despite prolonged therapy, raising concerns about treatment failure, resistance, or host-related factors. The following case highlights an unusual drug interaction that interfered with treatment efficacy, ultimately preventing complete clinical resolution.