Environmental occurrence of the Whipple's disease bacterium (Tropheryma whippelii)

Abstract

Whipple's disease is a systemic disorder in which a gram-positive rod-shaped bacterium is constantly present in infected tissues. After numerous unsuccessful attempts to culture this bacterium, it was eventually characterized by 16S rRNA gene analysis to be a member of the actinomycetes. The name Tropheryma whippelii was proposed. Until now, the bacterium has only been found in infected human tissues, but there is no evidence for human-to-human transmission. Here we report the detection of DNA specific for the Whipple's disease bacterium in 25 of 38 wastewater samples from five different sewage treatment plants in the area of Heidelberg, Germany. These findings provide the first evidence that T. whippelii occurs in the environment, within a polymicrobial community. This is in accordance with the phylogenetic relationship of this bacterium as well as with known epidemiological aspects of Whipple's disease. Our data argue for an environmental source for infection with the Whipple's disease bacterium.

FIG. 1

Map of the area around Heidelberg, Germany, displaying the rivers Rhine (Rhein) and Neckar, the relevant townships (shaded areas with names in capital letters), and the five sewage treatment plants (dots) from which samples were taken. The inset in the figure shows the localization of the area within Germany.

FIG. 2

Detection of DNA from the Whipple’s disease bacterium in sewage samples. Shown are the results of analyses of PCR products by polyacrylamide gel electrophoresis (A) and Southern blot hybridization with oligonucleotide whip4 (B). Lanes: 1 and 10, 100-bp DNA marker; 2, positive control consisting of a tissue digest (diluted 10⁻⁴) from the intestinal biopsy of a patient with Whipple’s disease (9); 3, negative control consisting of 10 μl of distilled water in the PCR mixture; 4 and 5, sewage samples from Heidelberg; 6 and 9, negative controls consisting of distilled water which was filtered and treated in the same way as the sewage; 7 and 8, sewage samples from Untere Hardt.