Tropheryma whipplei, the causative bacterium of Whipple's disease, can ă cause acute pneumonia. We performed a case-control study including ă patients with T. whipplei in bronchoalveolar lavages (BALs) and controls ă in order to compare patients' clinical statuses. ă We tested T. whipplei PCR from January 2013 to December 2014, in all the ă 1438 BALs in Marseille, France. Controls were hospitalized in the same ă unit during the same period and were comparable in age and sex. ă Eighty-eight BALs (6.1%) were positive for T. whipplei and 58 patients ă had pneumonia. Sixty-four patients were male with a mean age of 50.5 ă years. T. whipplei was commonly associated with aspiration pneumonia ă (18/88 patients compared with 6/88 controls, p 0.01) and was detected as ă a unique pathogen in nine cases. Overall, no difference was observed ă regarding immunocompromised status. Nevertheless, the six AIDS-infected ă patients in the T. whipplei group had a significantly lower CD4 level ă than the five AIDS-infected patients in the control group (49 vs. ă 320/mm(3), p 0.01); in addition, five patients were treated with tumour ă necrosis factor alpha inhibitors (including three treated by monocolonal ă antibodies and two with soluble receptor) compared with none of the ă controls (p 0.03). Pneumocystis jirovecii was frequently associated with ă the T. whipplei group (7/88 vs. 0/88 in control group), Pseudomonas ă aeruginosa was only detected in the control group (8/88). ă This study adds evidence for a causative role of T. whipplei in ă pneumonia. In the future, an experimental model of pneumonia induced by ă T. whipplei will prove its role in pneumonia. (C) 2016 European Society ă of Clinical Microbiology and Infectious Diseases. Published by Elsevier ă Ltd. All rights reserved.