title: Antagonism between Staphylococcus epidermidis and Propionibacterium acnes and its genomic basis.
abstract: BACKGROUND
  Propionibacterium acnes and Staphylococcus epidermidis live in close proximity on human skin, and both bacterial species can be isolated from normal and acne vulgaris-affected skin sites. The antagonistic interactions between the two species are poorly understood, as well as the potential significance of bacterial interferences for the skin microbiota. Here, we performed simultaneous antagonism assays to detect inhibitory activities between multiple isolates of the two species. Selected strains were sequenced to identify the genomic basis of their antimicrobial phenotypes.
  
  
  RESULTS
  First, we screened 77 P. acnes strains isolated from healthy and acne-affected skin, and representing all known phylogenetic clades (I, II, and III), for their antimicrobial activities against 12 S. epidermidis isolates. One particular phylogroup (I-2) exhibited a higher antimicrobial activity than other P. acnes phylogroups. All genomes of type I-2 strains carry an island encoding the biosynthesis of a thiopeptide with possible antimicrobial activity against S. epidermidis. Second, 20 S. epidermidis isolates were examined for inhibitory activity against 25 P. acnes strains. The majority of S. epidermidis strains were able to inhibit P. acnes. Genomes of S. epidermidis strains with strong, medium and no inhibitory activities against P. acnes were sequenced. Genome comparison underlined the diversity of S. epidermidis and detected multiple clade- or strain-specific mobile genetic elements encoding a variety of functions important in antibiotic and stress resistance, biofilm formation and interbacterial competition, including bacteriocins such as epidermin. One isolate with an extraordinary antimicrobial activity against P. acnes harbors a functional ESAT-6 secretion system that might be involved in the antimicrobial activity against P. acnes via the secretion of polymorphic toxins.
  
  
  CONCLUSIONS
  Taken together, our study suggests that interspecies interactions could potentially jeopardize balances in the skin microbiota. In particular, S. epidermidis strains possess an arsenal of different mechanisms to inhibit P. acnes. However, if such interactions are relevant in skin disorders such as acne vulgaris remains questionable, since no difference in the antimicrobial activity against, or the sensitivity towards S. epidermidis could be detected between health- and acne-associated strains of P. acnes.
authors.affiliation: Department of Biomedicine, Aarhus University, Aarhus, Denmark. gittejulie@gmail.com.
authors.forename: Gitte J M
authors.initials: GJ
authors.lastname: Christensen
authors.affiliation: Department of Biomedicine, Aarhus University, Aarhus, Denmark. christian.scholz@biomed.au.dk.
authors.forename: Christian F P
authors.initials: CF
authors.lastname: Scholz
authors.affiliation: Department of Molecular Biology and Genetics, Aarhus University, Aarhus, Denmark. jje@mbg.au.dk.
authors.forename: Jan
authors.initials: J
authors.lastname: Enghild
authors.affiliation: Institute of Medical Microbiology, University Hospital Hamburg-Eppendorf, Hamburg, Germany. rohde@uke.de.
authors.forename: Holger
authors.initials: H
authors.lastname: Rohde
authors.affiliation: Department of Biomedicine, Aarhus University, Aarhus, Denmark. kilian@biomed.au.dk.
authors.forename: Mogens
authors.initials: M
authors.lastname: Kilian
authors.affiliation: Department of Genomic and Applied Microbiology, Institute of Microbiology and Genetics, Georg-August University Göttingen, Göttingen, Germany. athuerm@gwdg.de.
authors.forename: Andrea
authors.initials: A
authors.lastname: Thürmer
authors.affiliation: Department of Genomic and Applied Microbiology, Institute of Microbiology and Genetics, Georg-August University Göttingen, Göttingen, Germany. ebrzusz@gwdg.de.
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Brzuszkiewicz
authors.affiliation: Department of Biomedicine, Aarhus University, Aarhus, Denmark. hans.lomholt@dadlnet.dk.
authors.forename: Hans B
authors.initials: HB
authors.lastname: Lomholt
authors.affiliation: Department of Biomedicine, Aarhus University, Aarhus, Denmark. brueggemann@microbiology.au.dk.
authors.forename: Holger
authors.initials: H
authors.lastname: Brüggemann
mesh_terms: D000152:Acne Vulgaris / Q000382:microbiology; D000898:Antibiosis / Q000235:genetics*; D055028:Comparative Genomic Hybridization; D004269:DNA, Bacterial / Q000235:genetics; D016680:Genome, Bacterial; D006801:Humans; D010802:Phylogeny; D011425:Propionibacterium acnes / Q000145:classification / Q000235:genetics* / Q000502:physiology; D017422:Sequence Analysis, DNA; D012867:Skin / Q000382:microbiology; D013212:Staphylococcus epidermidis / Q000145:classification / Q000235:genetics* / Q000502:physiology
chemical_list: D004269:DNA, Bacterial