RT Journal Article SR Electronic T1 Genome analysis of Legionella pneumophila ST23 from various countries reveals highly similar strains JF Life Science Alliance JO Life Sci. Alliance FD Life Science Alliance LLC SP e202101117 DO 10.26508/lsa.202101117 VO 5 IS 6 A1 Maria Luisa Ricci A1 Silvia Fillo A1 Andrea Ciammaruconi A1 Florigio Lista A1 Christophe Ginevra A1 Sophie Jarraud A1 Antonietta Girolamo A1 Fabrizio Barbanti A1 Maria Cristina Rota A1 Diane Lindsay A1 Jamie Gorzynski A1 Søren A Uldum A1 Sharmin Baig A1 Marina Foti A1 Giancarlo Petralito A1 Stefania Torri A1 Marino Faccini A1 Maira Bonini A1 Gabriella Gentili A1 Sabrina Senatore A1 Anna Lamberti A1 Joao André Carrico A1 Maria Scaturro YR 2022 UL https://www.life-science-alliance.org/content/5/6/e202101117.abstract AB Legionella pneumophila serogroup 1 (Lp1) sequence type (ST) 23 is one of the most commonly detected STs in Italy where it currently causes all investigated outbreaks. ST23 has caused both epidemic and sporadic cases between 1995 and 2018 and was analysed at genomic level and compared with ST23 isolated in other countries to determine possible similarities and differences. A core genome multi-locus sequence typing (cgMLST), based on a previously described set of 1,521 core genes, and single-nucleotide polymorphisms (SNPs) approaches were applied to an ST23 collection including genomes from Italy, France, Denmark and Scotland. DNAs were automatically extracted, libraries prepared using NextEra library kit and MiSeq sequencing performed. Overall, 63 among clinical and environmental Italian Lp1 isolates and a further seven and 11 ST23 from Denmark and Scotland, respectively, were sequenced, and pangenome analysed. Both cgMLST and SNPs analyses showed very few loci and SNP variations in ST23 genomes. All the ST23 causing outbreaks and sporadic cases in Italy and elsewhere, were phylogenetically related independent of year, town or country of isolation. Distances among the ST23s were further shortened when SNPs due to horizontal gene transfers were removed. The Lp1 ST23 isolated in Italy have kept their monophyletic origin, but they are phylogenetically close also to ST23 from other countries. The ST23 are quite widespread in Italy, and a thorough epidemiological investigation is compelled to determine sources of infection when this ST is identified in both LD sporadic cases and outbreaks.