In vivo endogenous spore formation by Coxiella burnetii in Q fever endocarditis.

AIMS To determine whether Coxiella burnetii, the aetiological agent of Q fever, undergoes endogenous spore-like formation, the crucial stage of the developmental cycle, in the infected cardiac valves of patients with chronic Q fever endocarditis. METHODS Surgically removed valves from three cases of Q fever endocarditis were processed for electron microscopy. Sections were stained with potassium permanganate and uranyl acetate before being extensively examined by transmission electron microscopy. RESULTS In all three cases endogenous spore-like formation was seen in the infected cardiac valves. CONCLUSIONS As the factors that govern sporogenesis in C burnetii are still largely unknown, it is uncertain how important are the implications of the discovery of endogenous spore-like formation in Q fever endocarditis. However, this finding may add new dimensions to current thinking about the treatment of chronic Q fever.