Whipple disease: a 15-year retrospective study on 36 patients with positive polymerase chain reaction for Tropheryma whipplei

Abstract Objectives Our institution performs microbiological diagnosis of Tropheryma whipplei since 2001, initially with a PCR targeting 16S rRNA before the development of a quantitative PCR in 2012. Here we report the clinical characteristics of a cohort of patients suffering from Whipple disease (WD) and evaluate the impact of these molecular techniques. Methods Patients with a positive PCR for T. whipplei between 2001 and 2016 were retrospectively collected from microbiological databases. Two infectious diseases specialists reviewed their medical records and classified them as definite WD, probable WD or carriage of T. whipplei without disease. Results 1153 samples were tested for T. whipplei, 76 samples taken from 36 patients were positive. Fifteen were considered as presenting a definite WD, seven as a probable WD, and 14 as carriers. Median age was 56.4 years (extremes: 6.6-76.1). Median time from symptoms to diagnosis was 3 years (2.5 months to 13.3 years). About 60% were immunosuppressed. The most frequent clinical presentations were joint pain (16/22), weight loss (15/22) and/or digestive tract disorder (15/22), 41% had neurological manifestations, 32% pulmonary involvement, and 32% lymphadenopathies. Bacterial load in faeces or saliva were 88’425 copies/ml (IQR 6’175-292’725) in definite and probable WD and 311 copies/ml (IQR 253-2’090) in carriers, respectively. We observed a 90% PPV above 32’200 copies/ml in faeces. Conclusions WD is a chronic multisytemic disease with frequent pulmonary involvement. Underlying immunodeficiency is commonly observed leading to more complex clinical presentation. Positive T. whipplei PCR in both stool and saliva has a high PPV. Moreover, patients with WD present higher bacterial load in faeces with a threshold of > 32’200 copies/ml predicting ongoing infection.