EVIDENCE THAT CHLAMYDIA-PNEUMONIAE CAUSES PNEUMONIA AND BRONCHITIS

An epidemic often provides an opportunity to obtain evidence of the et iologic association of a microorganism with disease. Chlamydia pneumon iae TWAR is a newly recognized organism whose relationship to disease is not completely understood. An outbreak of C pneumoniae infections f rom November 1990 to February 1991 was studied in University of Washin gton students. Twelve TWAR infections were identified serologically in 54 students with acute respiratory disease. The organism was isolated from 7 of the 12 and identified by the polymerase chain reaction (PCR ) in 2 that were isolation-negative. The organism was not found in any of the 42 serologically negative patients or in 51 control student pa tients without respiratory illness cultured in 1991. There was no evid ence of infection with Mycoplasma pneumoniae or respiratory viruses in the 12 patients with C. pneumoniae infection. During the 4-month outb reak, there was an increase in total pneumonia cases. These findings p rovide evidence for an etiologic association of C. pneumoniae with pne umonia and bronchitis.