title: Rapid species-level identification of vaginal and oral lactobacilli using MALDI-TOF MS analysis and 16S rDNA sequencing.
abstract: BACKGROUND
  Lactobacillus represents a large genus with different implications for the human host. Specific lactobacilli are considered to maintain vaginal health and to protect from urogenital infection. The presence of Lactobacillus species in carious lesions on the other hand is associated with progressive caries. Despite their clinical significance, species-level identification of lactobacilli still poses difficulties and mostly involves a combination of different phenotypic and genotypic methods. This study evaluated rapid MALDI-TOF MS analysis of vaginal and oral Lactobacillus isolates in comparison to 16S rDNA analysis.
  
  
  RESULTS
  Both methods were used to analyze 77 vaginal and 21 oral Lactobacillus isolates. The concordance of both methods was at 96% with five samples discordantly identified. Fifteen different Lactobacillus species were found in the vaginal samples, primarily L. iners, L. crispatus, L. jensenii and L. gasseri. In the oral samples 11 different species were identified, mostly L. salivarius, L. gasseri, L. rhamnosus and L. paracasei. Overall, the species found belonged to six different phylogenetic groups. For several samples, MALDI-TOF MS analysis only yielded scores indicating genus-level identification. However, in most cases the species found agreed with the 16S rDNA analysis result.
  
  
  CONCLUSIONS
  MALDI-TOF MS analysis proved to be a reliable and fast tool to identify lactobacilli to the species level. Even though some results were ambiguous while 16S rDNA sequencing yielded confident species identification, accuracy can be improved by extending reference databases. Thus, mass spectra analysis provides a suitable method to facilitate monitoring clinically relevant Lactobacillus species.
authors.affiliation: Department of Operative Dentistry and Periodontology, Albert-Ludwigs-University, Hugstetter Strasse 55, Freiburg, Germany. annette.anderson@uniklinik-freiburg.de.
authors.forename: Annette Carola
authors.initials: AC
authors.lastname: Anderson
authors.affiliation: Department of Hygiene and Microbiology, Albert-Ludwigs-University, Hermann-Herder-Str. 11, Freiburg, Germany. msanunu@gmail.com.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Sanunu
authors.affiliation: Department of Hygiene and Microbiology, Albert-Ludwigs-University, Hermann-Herder-Str. 11, Freiburg, Germany. christian.schneider@uniklinik-freiburg.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Schneider
authors.affiliation: Department for Gynaecology, Medical Center, Albert-Ludwigs-University, Hugstetter Strasse 55, Freiburg, Germany. annette.anderson@uniklinik-freiburg.de.
authors.forename: Andreas
authors.initials: A
authors.lastname: Clad
authors.affiliation: Department of Operative Dentistry and Periodontology, Albert-Ludwigs-University, Hugstetter Strasse 55, Freiburg, Germany. lamprini.karygianni@uniklinik-freiburg.de.
authors.forename: Lamprini
authors.initials: L
authors.lastname: Karygianni
authors.affiliation: Department of Operative Dentistry and Periodontology, Albert-Ludwigs-University, Hugstetter Strasse 55, Freiburg, Germany. elmar.hellwig@uniklinik-freiburg.de.
authors.forename: Elmar
authors.initials: E
authors.lastname: Hellwig
authors.affiliation: Department of Operative Dentistry and Periodontology, Albert-Ludwigs-University, Hugstetter Strasse 55, Freiburg, Germany. ali.al-ahmad@uniklinik-freiburg.de.
authors.forename: Ali
authors.initials: A
authors.lastname: Al-Ahmad
mesh_terms: D000328:Adult; D000368:Aged; D001431:Bacteriological Techniques / Q000379:methods*; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D005260:Female; D006801:Humans; D007778:Lactobacillus / Q000737:chemistry / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D008875:Middle Aged; D025202:Molecular Diagnostic Techniques / Q000379:methods*; D008969:Molecular Sequence Data; D009055:Mouth / Q000382:microbiology*; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D014621:Vagina / Q000382:microbiology*; D055815:Young Adult
chemical_list: D004269:DNA, Bacterial; D004275:DNA, Ribosomal; D012336:RNA, Ribosomal, 16S