BARTONELLA QUINTANA INVADES AND MULTIPLIES WITHIN ENDOTHELIAL-CELLS IN-VITRO AND IN-VIVO AND FORMS INTRACELLULAR BLEBS

Bartonella quintana, the aetiologic agent of trench fever, has recentl y been implicated in culture-negative endocarditis and bacteraemia amo ngst homeless people. B. quintana is a fastidious slow-growing organis m. A tissue culture system of human endothelial cells was developed in which B. quintana grew intracellularly. Observation of the different steps during infection of these cells demonstrated that the bacteria a dhered to and penetrated the cells by phagocytosis. During the preadhe rence stage, most bacteria exhibited surface appendages that resembled those described for Salmonella typhimurium and which may mediate spec ific interactions between the eucaryotic cell and the bacterium. Soon after the engulfment step, the bacterium appeared in a cell vacuole wh ere it multiplied, giving the typical aspect of morulae which has also been reported with Ehrlichiae or Chlamydiae. In older cultures, the c oexistence of bacteria and huge quantities of vesicle-like structures in the same vacuole were noted. These vesicle-like structures were als o found with agar-grown bacteria and were identified as membrane blebs . Microscopic observation of heart valves from B. quintana endocarditi s patients demonstrated the intracellular location of B. quintana in v ivo. This intracellular location of B. quintana should now be consider ed in further studies on the pathogenesis of the diseases it causes.