Detection of three different types of 'Tropheryma whippelii' directly from clinical specimens by sequencing, single-strand conformation polymorphism (SSCP) analysis and type-specific PCR of their 16S-23S ribosomal intergenic spacer region.

The 16S-23S rDNA intergenic spacer region of organisms identical with or closely related to 'Tropheryma whippelii', the uncultivated causative agent of Whipple's disease, was analysed directly from 38 clinical specimens of 28 patients using a specific nested PCR followed by direct sequencing. As compared to the reference sequence in public databases, two novel 'T. whippelii' spacer types were recognized. In the absence of DNA-DNA hybridization data it is uncertain whether the three types found represent subtypes of a single species or three different but closely related species. Methods were developed to detect all three variants by single-strand conformation polymorphism analysis and by type-specific PCR assays, thus allowing the screening of large numbers of specimens. Further studies may provide a clue to the possible associations between the type of infecting strain and the various clinical presentations of Whipple's disease.