Diagnostic application of a polymerase chain reaction assay for the Whipple's disease bacterium to intestinal biopsies

Abstract

Background & aims: The uncultured Whipple's disease bacterium (Tropheryma whippelii) was characterized in 1991-1992 by polymerase chain reaction (PCR) and sequencing of the bacterial 16S ribosomal RNA gene. The aim of this study was to develop a PCR assay for diagnostic purposes.

Methods: Modified primers for PCR and a specific probe for hybridization were designed. The specificity of this PCR assay was tested using 37 bacterial control strains and intestinal biopsy samples from 16 patients without Whipple's disease. The sensitivity was tested in 88 intestinal biopsy samples from 35 patients with Whipple's disease.

Results: PCR and hybridization were negative in all 37 bacterial controls and in all 16 patients without Whipple's disease. Before therapy, DNA of T. whippelii was detected in all 30 patients with Whipple's disease from whom formalin-fixed biopsy material was available, whereas Bouin-fixed material was negative. During and after treatment, PCR was negative in 23 of the 24 patients who were followed up. Generally, conversion to negative occurred within 1 year. Despite negative intestinal PCR, symptomatic cerebral Whipple's disease appeared in 3 patients.

Conclusions: This PCR assay is specific and sensitive and is applicable as a diagnostic test. However, PCR from intestinal biopsy samples seems less helpful for monitoring the effect of treatment.