title: Rapid identification of Legionella species by mass spectrometry.
abstract: Legionella species are facultative, intracellular bacteria that infect macrophages and protozoa, with the latter acting as transmission vectors to humans. These fastidious bacteria mostly cause pulmonary tract infections and are routinely identified by various molecular methods, mainly PCR targeting the mip gene and sequencing, which are expensive and time-consuming. Recently, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has emerged as a rapid and inexpensive method for identification of bacterial species. This study evaluated the use of MALDI-TOF-MS for rapid species and serogroup identification of 21 Legionella species recognized as human pathogens. To this end, a reference MS database was developed including 59 Legionella type strains, and a blind test was performed using 237 strains from various species. Two hundred and twenty-three of the 237 strains (94.1 %) were correctly identified at the species level, although ten (4.2 %) were identified with a score lower than 2.0. Fourteen strains (5.9 %) from eight species were misidentified at the species level, including seven (3.0 %) with a significant score, suggesting an intraspecific variability of protein profiles within some species. MALDI-TOF-MS was reproducible but could not identify Legionella strains at the serogroup level. When compared with mip gene sequencing, MALDI-TOF-MS exhibited a sensitivity of 99.2 and 89.9 % for the identification of Legionella strains at the genus and species level, respectively. This study demonstrated that MALDI-TOF-MS is a reliable tool for the rapid identification of Legionella strains at the species level.
authors.affiliation: URMITE CNRS-IRD UMR 6236, Faculté de Médecine, 27 boulevard Jean Moulin, 13385 Marseille Cedex 05, France.
authors.forename: Claire
authors.initials: C
authors.lastname: Moliner
authors.affiliation: Hospices Civils de Lyon, Faculté de Médecine Lyon Est Claude Bernard, Lyon, France.|Université de Lyon, Lyon, France.|INSERM, U851, 21 avenue Tony Garnier, 69007 Lyon, France.|Université Lyon 1, IFR128, Lyon, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Ginevra
authors.affiliation: Université Lyon 1, IFR128, Lyon, France.|Hospices Civils de Lyon, Faculté de Médecine Lyon Est Claude Bernard, Lyon, France.|Université de Lyon, Lyon, France.|INSERM, U851, 21 avenue Tony Garnier, 69007 Lyon, France.
authors.forename: Sophie
authors.initials: S
authors.lastname: Jarraud
authors.affiliation: Fédération de Microbiologie Clinique, Hôpital de la Timone, 264 rue Saint-Pierre, 13385 Marseille Cedex 05, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Flaudrops
authors.affiliation: Fédération de Microbiologie Clinique, Hôpital de la Timone, 264 rue Saint-Pierre, 13385 Marseille Cedex 05, France.
authors.forename: Marielle
authors.initials: M
authors.lastname: Bedotto
authors.affiliation: Fédération de Microbiologie Clinique, Hôpital de la Timone, 264 rue Saint-Pierre, 13385 Marseille Cedex 05, France.
authors.forename: Carine
authors.initials: C
authors.lastname: Couderc
authors.affiliation: Université Lyon 1, IFR128, Lyon, France.|INSERM, U851, 21 avenue Tony Garnier, 69007 Lyon, France.|Université de Lyon, Lyon, France.|Hospices Civils de Lyon, Faculté de Médecine Lyon Est Claude Bernard, Lyon, France.
authors.forename: Jerome
authors.initials: J
authors.lastname: Etienne
authors.affiliation: Fédération de Microbiologie Clinique, Hôpital de la Timone, 264 rue Saint-Pierre, 13385 Marseille Cedex 05, France.|URMITE CNRS-IRD UMR 6236, Faculté de Médecine, 27 boulevard Jean Moulin, 13385 Marseille Cedex 05, France.
authors.forename: Pierre-Edouard
authors.initials: PE
authors.lastname: Fournier
mesh_terms: D001431:Bacteriological Techniques / Q000379:methods*; D006801:Humans; D007875:Legionella / Q000737:chemistry* / Q000302:isolation & purification*; D007876:Legionellosis / Q000175:diagnosis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*