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Detection of Tropheryma whipplei in stool samples by one commercial and two in‐house real‐time PCR assays
Author(s) -
Frickmann Hagen,
Hanke Miriam,
Hahn Andreas,
Schwarz Norbert G.,
Landt Olfert,
Moter Annette,
Kikhney Judith,
Hinz Rebecca,
Rojak Sandra,
Dekker Denise,
Tannich Egbert,
Podbielski Andreas
Publication year - 2019
Publication title -
tropical medicine and international health
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.056
H-Index - 114
eISSN - 1365-3156
pISSN - 1360-2276
DOI - 10.1111/tmi.13172
Subject(s) - tropheryma whipplei , whipple disease , whipple's disease , feces , real time polymerase chain reaction , biology , confidence interval , tropical disease , epidemiology , kappa , medicine , virology , gastroenterology , disease , veterinary medicine , microbiology and biotechnology , gene , coeliac disease , biochemistry , intestinal malabsorption , linguistics , philosophy
Objective Tropheryma whipplei , the causative agent of Whipple's disease, can also be identified in stool samples of humans without systemic disease. It is much more frequently detected in human stool samples in tropical environments than in industrialized countries. PCR ‐screening has been applied for point prevalence studies and environmental assessments in tropical settings, but results depend on the applied assay. We compared one commercial qPCR kit with two well‐described in‐house assays for detection of T. whipplei from stool. Methods Residual materials from nucleic acid extractions of stool samples from two groups with presumably different prevalences and increased likelihood of being colonized or infected by T. whipplei were tested. One group comprised 300 samples from study participants from western Africa (group 1); the second group was of 300 returnees from tropical deployments (group 2). Each sample was assessed with all three qPCR assays. Cycle threshold ( C t ) values were descriptively compared. Results Based solely on mathematical modeling, the three PCR assays showed considerably different detection rates of T. whipplei DNA in stool samples (kappa 0.67 (95% confidence interval [0.60, 0.73])). Considering the calculated test characteristics, prevalence of 28.3% for group 1 and 5.0% for group 2 was estimated. Discordant test results were associated with later C t values. The study did not validate the assays for the detection of T. whipplei in Whipple's disease and for diagnostic purposes since clinical specificity and sensitivity were not investigated. Conclusions In spite of the observed diagnostic uncertainty, PCR ‐based screening approaches can be used for epidemiological purposes and environmental samples to define the source and reservoir in resource‐limited tropical settings if prevalence is calculated using diagnostic accuracy‐adjusted methods.