Persistent cardiac and urinary tract infections with Borrelia burgdorferi in experimentally infected Syrian hamsters.

The heart can be severely affected in humans with Lyme disease, causing conduction defects and, rarely, heart failure. Although immunodeficient and young mice may develop cardiac lesions, cultivation of Borrelia burgdorferi from cardiac tissues of experimentally infected animals has not been reported previously. We infected Syrian hamsters with B. burgdorferi 297 and found a marked tropism of the spirochete for myocardial and urinary tract tissues. Fifty-six of 57 hearts (98%) and 52 of 58 bladders (90%) were culture positive. The cardiac infection was persistent and could be documented in 21 of 22 hearts (96%) cultured from days 28 to 84 postinfection. The urinary tract was also a site of persistent infection in most animals, with 18 of 23 bladders (78%) being culture positive from days 28 to 84. The persistence of spirochetes was specific for the heart and bladder, as indicated by negative cultures of specimens from the liver and spleen, in which only 1 of 23 cultures was positive from days 28 to 84. Because of the high isolation rates, tropism, and persistence that we found for B. burgdorferi in the hamster heart and bladder, these sites will be useful and important for the cultivation of spirochetes in experimental studies that evaluate the efficacies both of candidate vaccines in preventing infection and of antibiotics in eradicating organisms from privileged sites. In addition, the clear demonstration of persistent cardiac infection with B. burgdorferi may provide a useful model for studying the pathogenesis of cardiac Lyme disease.