title: Comparison of pathogenic and non-pathogenic Enterococcus cecorum strains from different animal species.
abstract: BACKGROUND
  Enterococcus cecorum (EC) infection currently is one of the most important bacterial diseases of modern broiler chickens but can also affect ducks or other avian species. However, little is known concerning pathogenesis of EC and most studies concentrate on examinations of EC strains from broilers only. The objective of this study was to compare pathogenic and commensal EC strains from different animal species concerning different phenotypic and genotypic traits.
  
  
  RESULTS
  Pathogenic and commensal EC strains were not clearly separated from each other in a phylogenetic tree based on partial sequences of the 16S-rRNA-gene and also based on the fatty acid profile determined with gas chromatography. C12:0, C14:0, C15:0, C16:0, C17:0, C18:0, C18:1w7c, C18:1w9c and C20:4w6,9,12,15c were detected as the major fatty acids. None of the 21 pathogenic EC strains was able to utilize mannitol, while 9 of 29 commensal strains were mannitol positive. In a dendrogram based on MALDI-TOF MS data, pathogenic strains were not clearly separated from commensal isolates. However, significant differences concerning the prevalence of several mass peaks were confirmed between the two groups. Two different antisera were produced but none of the serotypes was predominantly found in the pathogenic or commensal EC isolates. Enterococcal virulence factors gelE, esp, asa1, ccf, hyl and efaAfs were only detected in single isolates via PCR. No virulence factor was found significantly more often in the pathogenic isolates. The chicken embryo lethality of the examined EC isolates varied from 0 up to 100%. The mean embryo lethality in the pathogenic EC isolates was 39.7%, which was significantly higher than the lethality of the commensal strains, which was 18.9%. Additionally, five of the commensal isolates showed small colony variant growth, which was never reported for EC before.
  
  
  CONCLUSIONS
  Pathogenic and commensal EC isolates from different animal species varied in chicken embryo lethality, in their ability to metabolize mannitol and probably showed divergent mass peak patterns with MALDI-TOF MS. These differences may be explained by a separate evolution of pathogenic EC isolates. Furthermore, different serotypes of EC were demonstrated for the first time.
authors.affiliation: Clinic for Poultry, University of Veterinary Medicine Hannover, Buenteweg 17, D-30559, Hannover, Germany. arne.jung@tiho-hannover.de.
authors.forename: Arne
authors.identifier: http://orcid.org/0000-0002-9866-6841
authors.initials: A
authors.lastname: Jung
authors.affiliation: RIPAC LABOR GmbH, Am Muehlenberg 11, D-14476, Potsdam-Golm, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Metzner
authors.affiliation: Clinic for Poultry, University of Veterinary Medicine Hannover, Buenteweg 17, D-30559, Hannover, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Ryll
mesh_terms: D000818:Animals; D001483:Base Sequence; D018929:Cell Culture Techniques; D002642:Chick Embryo / Q000382:microbiology; D002645:Chickens; D002849:Chromatography, Gas; D004269:DNA, Bacterial; D004372:Ducks; D016983:Enterococcus / Q000145:classification / Q000235:genetics / Q000302:isolation & purification* / Q000472:pathogenicity*; D005227:Fatty Acids / Q000032:analysis; D005798:Genes, Bacterial; D005838:Genotype; D016908:Gram-Positive Bacterial Infections / Q000453:epidemiology / Q000382:microbiology* / Q000662:veterinary*; D007106:Immune Sera; D008353:Mannitol / Q000378:metabolism; D010641:Phenotype; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000662:veterinary; D011201:Poultry Diseases / Q000453:epidemiology / Q000382:microbiology*; D015995:Prevalence; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012703:Serotyping / Q000662:veterinary; D037521:Virulence Factors / Q000235:genetics
chemical_list: D004269:DNA, Bacterial; D005227:Fatty Acids; D007106:Immune Sera; D012336:RNA, Ribosomal, 16S; D037521:Virulence Factors; D008353:Mannitol
keywords: Chicken embryo lethality assay; Enterococcus cecorum; Fatty acid profile; MALDI-TOF mass spectrometry; Poultry; Serotyping; Virulence factors