THE ROLE OF ARBITRARILY PRIMED PCR IN IDENTIFYING THE SOURCE OF AN OUTBREAK OF LEGIONNAIRES-DISEASE

An outbreak of community-acquired Legionnaires' disease (LD) occurred in Providence, R.I., in fall 1993. To find the outbreak source, exposu res of 17 case patients mere compared to those of 33 matched controls. Case patients were more likely than controls to have visited a sectio n of downtown (area A) during the 2 weeks before illness (11 [65%] ver sus 9 [27%]; matched odds ratio, 6.5; P = 0.01), Water samples were cu ltured from 27 aerosol-producing devices within area A. Legionella pne umophila serogroup 1 isolates underwent monoclonal antibody (MAb) subt yping and arbitrarily primed PCR (AP-PCR), All four L. pneumophila ser ogroup 1 isolates available from case patients who visited area A had identical MAb and AP-PCR patterns. Among 14 environmental isolates, 5 had MAb patterns that matched the case patient isolates, but only 1 ha d a matching AP-PCR pattern, This investigation implicates a cooling t ower in area A as the outbreak source and illustrates the usefulness o f AP-PCR for identifying sources of LD outbreaks.