Genotyping reveals a wide heterogeneity of Tropheryma whipplei. Microbiology. 2008 Feb;154(Pt 2):521-7.

Tropheryma whipplei, the causative agent of Whipple's disease, is associated with various clinical manifestations as well as an asymptomatic carrier status, and it exhibits genetic heterogeneity. However, relationships that may exist between environmental and clinical strains are unknown. Herein, we developed an efficient genotyping system based on four highly variable genomic sequences (HVGSs) selected on the basis of genome comparison. We analysed 39 samples from 39 patients with Whipple's disease and 10 samples from 10 asymptomatic carriers. Twenty-six classic gastrointestinal Whipple's disease associated with additional manifestations, six relapses of classic Whipple's disease (three gastrointestinal and three neurological relapses), and seven isolated infections due to T. whipplei without digestive involvement (five endocarditis, one spondylodiscitis and one neurological infection) were included in the study. We identified 24 HVGS genotypes among 39 T. whipplei DNA samples from the patients and 10 T. whipplei DNA samples from the asymptomatic carriers. No significant correlation between HVGS genotypes and clinical manifestations of Whipple's disease, or asymptomatic carriers, was found for the 49 samples tested. Our observations revealed a high genetic diversity of T. whipplei strains that is apparently independent of geographical distribution and unrelated to bacterial pathogenicity. Genotyping in Whipple's disease may, however, be useful in epidemiological studies.

Decision analysis: an aid to the diagnosis of Whipple's disease.Aliment Pharmacol Ther. 2006 Mar 15;23(6):833-40.

BACKGROUND: Diagnosis of Whipple's disease, a rare systemic infection affecting predominantly the small bowel, is based on the identification of the bacterium Tropheryma whipplei. AIMS: To make explicit diagnostic uncertainties in Whipple's disease through a decision analysis, considering two different clinical scenarios at presentation. METHODS: Using appropriate software, a decision tree estimated the consequences after testing different strategies for diagnosis of Whipple's disease. Probabilities and outcomes to determine the optimum expected value were based on MEDLINE search. RESULTS: In patients with clinically-predominant intestinal involvement, diagnostic strategies considering intestinal biopsy for histology (including appropriate staining) and the polymerase chain reaction testing for bacterial DNA were similarly effective. In case of failure of one procedure, the best sequential choice was a polymerase chain reaction analysis after a negative histology. Of the five strategies tested for cases with predominant focal neurological involvement, the stereotaxis cerebral biopsy evidenced the highest expected value. However, using quality-adjusted life-years considering the morbidity of methods, intestinal biopsy for PCR determination was the best choice. CONCLUSIONS: In patients with Whipple's disease having predominant digestive involvement, intestinal biopsies for histology should be indicated first and, if negative, a bacterial polymerase chain reaction determination should be the next option. Although the molecular polymerase chain reaction assessment of cerebral biopsies has the highest diagnostic yield in neurological Whipple's disease, its associated morbidity means that analyses of intestinal samples are more appropriate.