Systemic Character of Legionnaires’ Disease – A Murine Model

In contrast to lung infection caused by Legionella pneumophila, little is known about the pathogenesis of this disease in other organs. In this study, we analyzed the number of colony forming units (CFU) of legionellae not only in lungs but also in EDTA plasma, liver, spleen and kidneys. The number of CFU was determined 2, 24, 48, 72 and 168 h after intratracheal inoculation. Results showed that the inflammatory response was mostly pronounced in lungs. Legionellae, however, were also found in EDTA plasma and all the other investigated organs. The duration of infection was most protracted in lungs, with persistence for at least 168 h. In the remaining organs, legionellae were found for a maximum of 72 h after inoculation. Besides the culture methods used for detection of CFU we also used LightCycler (LC) PCR to confirm the presence of bacteria in the blood of intratracheally infected mice. By this method the bacterial DNA could be detected during the first two days of post infection