Tropheryma whipplei DNA in bronchoalveolar lavage samples: a case control study

Tropheryma whipplei, the causative bacterium of Whipple's disease, can cause acute pneumonia. We performed a case-control study including patients with T. whipplei in bronchoalveolar lavages (BALs) and controls in order to compare patients' clinical statuses. We tested T. whipplei PCR from January 2013 to December 2014, in all the 1438 BALs in Marseille, France. Controls were hospitalized in the same unit during the same period and were comparable in age and sex. Eighty-eight BALs (6.1%) were positive for T. whipplei and 58 patients had pneumonia. Sixty-four patients were male with a mean age of 50.5 years. T. whipplei was commonly associated with aspiration pneumonia (18/88 patients compared with 6/88 controls, p 0.01) and was detected as a unique pathogen in nine cases. Overall, no difference was observed regarding immunocompromised status. Nevertheless, the six AIDS-infected patients in the T. whipplei group had a significantly lower CD4 level than the five AIDS-infected patients in the control group (49 vs. 320/mm³, p 0.01); in addition, five patients were treated with tumour necrosis factor alpha inhibitors (including three treated by monocolonal antibodies and two with soluble receptor) compared with none of the controls (p 0.03). Pneumocystis jirovecii was frequently associated with the T. whipplei group (7/88 vs. 0/88 in control group), Pseudomonas aeruginosa was only detected in the control group (8/88). This study adds evidence for a causative role of T. whipplei in pneumonia. In the future, an experimental model of pneumonia induced by T. whipplei will prove its role in pneumonia.