Pleural infection caused by Capnocytophaga canimorsus, formerly CDC group DF-2.

An 80-year-old man with Waldenström's macroglobulinemia developed pneumonia and empyema due to Capnocytophaga canimorsus (formerly CDC group DF-2). No growth was detected in blood cultures, but the organism was identified from cultures of pleural fluid. The infection responded well to antibiotics and drainage via a chest tube. To our knowledge, this is the first report of a clinical isolate of C. canimorsus from a pulmonary source. The absence of concurrent bacteremia raises the possibility that the lower respiratory tract can be the site of primary infection with this organism.