title: Coryneform bacteria in human semen: inter-assay variability in species composition detection and biofilm production ability.
abstract: BACKGROUND
  Coryneform bacteria constitute an important segment of male urogenital microbiota. They have been generally considered as saprophytes, although some species have been associated with prostatitis as well. At the same time, biofilm infections have been suspected as a cause of prostatitis.
  
  
  OBJECTIVE
  To identify a set of coryneform bacteria isolated from semen of either healthy men or prostatitis patients applying different methods to reveal inter-assay variability and to determine their ability of adhesion and biofilm production.
  
  
  METHODS
  Coryneform bacteria were identified by API Coryne 2.0 biochemical identification system and 16S rDNA sequencing using different primer sets. Quantitative assessment of biofilm production was performed using crystal violet binding assay method.
  
  
  RESULTS
  The most common species were Corynebacterium seminale, C. minutissimum, and Dermabacter hominis. Altogether 14 species and related genera were found. We observed the best inter-assay agreement when identifying C. seminale. Biofilm was observed in 7 out of 24 strains. The biofilm-producing strains belonged to Arthrobacter cumminsii, Dermabacter hominis, C. minutissimum, and Actinomyces neuii. No differences were found between the strains originating from prostatitis patients and healthy men. Dermabacter hominis strains were more potent biofilm producers than C. seminale strains (p=0.048).
  
  
  CONCLUSIONS
  We can conclude that a wide variety of coryneform bacteria can be found from the male genital tract, although their exact identification is problematic due to insufficient representation in databases. Nearly one third of the strains are able to form biofilm that may give them an advantage for surviving several host- and treatment-related conditions.
authors.affiliation: Department of Microbiology, University of Tartu, Tartu, Estonia.
authors.forename: Silver
authors.initials: S
authors.lastname: Türk
authors.affiliation: Sexually Transmitted Diseases Centre, Santa Maria Annunziata Hospital, Florence, Italy.
authors.forename: Sandra
authors.initials: S
authors.lastname: Mazzoli
authors.affiliation: Department of Microbiology, University of Tartu, Tartu, Estonia.
authors.forename: Jelena
authors.initials: J
authors.lastname: Stšepetova
authors.affiliation: Department of Microbiology, University of Tartu, Tartu, Estonia.
authors.forename: Julia
authors.initials: J
authors.lastname: Kuznetsova
authors.affiliation: Department of Microbiology, University of Tartu, Tartu, Estonia ; Competence Centre on Reproductive Medicine and Biology, Tartu, Estonia.
authors.forename: Reet
authors.initials: R
authors.lastname: Mändar
keywords: Corynebacterium; biofilm; coryneform bacteria; identification; prostatitis; semen