Targeting single-nucleotide polymorphisms in the 16S rRNA gene to detect and differentiate Legionella pneumophila and non-Legionella pneumophila species.

Abstract

A PCR-based method targeting single-nucleotide polymorphisms (SNPs) in the 16S rRNA gene was developed for differential identification of Legionella pneumophila and non-Legionella pneumophila. Based on the bioinformatics analysis for 176 Legionella 16S rRNA gene fragments of 56 different Legionella species, a set of SNPs, A(628)C(629) was found to be highly specific to L. pneumophila strains. A multiplex assay was designed that was able to distinguish sites with limited sequence heterogeneity between L. pneumophila and non-L. pneumophila in the targeted 16S rRNA gene. The assay amplified a 261-bp amplicon for Legionella spp. and a set of 203- and 97-bp amplicons only specific to L. pneumophila species. Among 49 ATCC strains and 284 Legionella isolates from environmental water and clinical samples, 100% of L. pneumophila and non-L. pneumophila strains were correctly identified and differentiated by this assay. The assay presents a more rapid, sensitive and alternative method to the currently available PCR-sequencing detection and differentiation method.