title: Detection of Legionella species in respiratory specimens using PCR with sequencing confirmation.
abstract: Legionella spp. are a common cause of community-acquired respiratory tract infections and an occasional cause of nosocomial pneumonia. A PCR method for the detection of legionellae in respiratory samples was evaluated and was compared to culture. The procedure can be performed in 6 to 8 h with a commercially available DNA extraction kit (Qiagen, Valencia, Calif.) and by PCR with gel detection. PCR is performed with primers previously determined to amplify a 386-bp product within the 16S rRNA gene of Legionella pneumophila. We can specifically detect the clinically significant Legionella species including L. pneumophila, L. micdadei, L. longbeachae, L. bozemanii, L. feeleii, and L. dumoffii. The assay detects 10 fg (approximately two organisms) of legionella DNA in each PCR. Of 212 clinical specimens examined by culture, 100% of the culture-positive samples (31 of 31) were positive by this assay. By gel detection of amplification products, 12 of 181 culture-negative samples were positive for Legionella species by PCR, resulting in 93% specificity. Four of the 12 samples with discrepant results (culture negative, PCR positive) were confirmed to be positive for Legionella species by sequencing of the amplicons. The legionella-specific PCR assay that is described demonstrates high sensitivity and high specificity for routine detection of legionellae in respiratory samples.
authors.affiliation: Associated Regional and University Pathologists Institute for Clinical and Experimental Pathology, Salt Lake City, Utah, USA. cloudjl@arup-lab.com
authors.forename: J L
authors.initials: JL
authors.lastname: Cloud
authors.forename: K C
authors.initials: KC
authors.lastname: Carroll
authors.forename: P
authors.initials: P
authors.lastname: Pixton
authors.forename: M
authors.initials: M
authors.lastname: Erali
authors.forename: D R
authors.initials: DR
authors.lastname: Hillyard
mesh_terms: D001483:Base Sequence; D001992:Bronchoalveolar Lavage Fluid / Q000382:microbiology; D017931:DNA Primers; D014644:Genetic Variation; D006801:Humans; D007875:Legionella / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D016952:Legionella pneumophila / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D007876:Legionellosis / Q000175:diagnosis*; D007877:Legionnaires' Disease / Q000175:diagnosis; D008168:Lung / Q000382:microbiology; D008969:Molecular Sequence Data; D010996:Pleural Effusion / Q000382:microbiology; D016133:Polymerase Chain Reaction / Q000379:methods; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016415:Sequence Alignment; D012689:Sequence Homology, Nucleic Acid; D013183:Sputum / Q000382:microbiology
chemical_list: D017931:DNA Primers; D012336:RNA, Ribosomal, 16S