Community- and hospital-acquired pneumonia associated with Chlamydia TWAR infection demonstrated serologically.

Serum specimens from 198 patients with pneumonia hospitalized in Seattle between October 1980 and April 1981 were retrospectively tested for antibody against a recently described Chlamydia organism called TWAR. They had been previously tested for antibody for some viruses and Mycoplasma. Twenty (10%) had serologic evidence of recent TWAR infection. The hospital records of the patients with acute TWAR antibody and an equal number of matched controls were examined for clinical characteristics, laboratory tests, treatment, and course during the hospital stay. It was not possible clinically or roentgenographically to distinguish pneumonia associated with TWAR antibody from pneumonia in the controls. Nine of 20 patients with TWAR antibody acquired pneumonia during their hospital stay. The mode of transmission in the hospital was not determined. All the patients with hospital-acquired pneumonia had been intubated, and all had had some surgical procedure. Ten of 20 control patients had onset of their pneumonia in the hospital. Fifteen (11%) of 142 of the patients with pneumonia had evidence of influenza A virus infection. The clinical characteristics of their pneumonias were similar to those of the patients with acute TWAR antibody.