Diagnosis of Legionella pneumophila infection by polymerase chain reaction.

Abstract

We examined the application of the polymerase chain reaction (PCR) for the diagnosis of legionellosis. Eight intratracheal aspirates were collected from a patient with pneumonia caused by Legionella pneumophila serogroup 2, and serial 10-fold dilutions of the samples were obtained. Two samples were positive for L. pneumophila by the direct fluorescent antibody (DFA) method down to a 10(-2) concentration, and one was positive down to a 10(-4) concentration. PCR was positive for all eight samples, and the sensitivity was greater than that of the DFA method. Only one of the eight samples yielded organisms in culture: the L. pneumophila serogroup 2 strain was isolated on buffered charcoal yeast extract alpha agar as an atypical white, papillate colony.