title: D-amino acids do not inhibitPseudomonas aeruginosabiofilm formation.
abstract: Pseudomonas aeruginosa, a known biofilm-forming organism, is an opportunistic pathogen that plays an important role in chronic otitis media, tracheitis, cholesteatoma, chronic wounds, and implant infections. Eradication of biofilm infections has been a challenge because the biofilm phenotype provides bacteria with a protective environment from the immune system and antibiotics; thus, there has been great interest in adjunctive molecules that may inhibit biofilm formation or cause biofilm dispersal. There are reports that D-amino acids may inhibit biofilms. In this study, we test the ability of various D-amino acids to inhibitP. aeruginosabiofilm formation in vitro.
  
  
  
  We evaluated the effect of D-alanine (10 mM), D-leucine (10 mM), D-methionine (10 mM), D-tryptophan (10 mM), and D-tyrosine (10 uM and 1 mM) on biofilm formation in two commonly studied laboratory strains ofP. aeruginosa: PAO1 and PA14.
  
  
  
  Biofilms were grown in 24-well and 96-well tissue culture plates, documented photographically and stained with 0.1% crystal violet and solubilized in 33% glacial acetic acid for quantification.
  
  
  
  In strains PAO1 and PA14, the addition of D-amino acids did not result in an inhibitory effect on biofilm growth in 24-well plates. Repeating the study in 96-well plates confirmed our findings that D-amino acids do not inhibit biofilm formation ofP. aeruginosa.
  
  
  
  We conclude that D-amino acids only slow the production of biofilms rather than completely prevent biofilm formation; therefore, D-amino acids represent a poor option for potential clinically therapeutic interventions.
  
  
  
  N/A.
authors.affiliation: Department of Otolaryngology Washington University in St. Louis School of Medicine St. Louis Missouri U.S.A.
authors.forename: Wee Tin K
authors.initials: WT
authors.lastname: Kao
authors.affiliation: Department of Otolaryngology Washington University in St. Louis School of Medicine St. Louis Missouri U.S.A.
authors.forename: Mitchell
authors.initials: M
authors.lastname: Frye
authors.affiliation: Department of Molecular Microbiology Washington University in St. Louis School of Medicine St. Louis Missouri U.S.A.
authors.forename: Patricia
authors.initials: P
authors.lastname: Gagnon
authors.affiliation: Department of Molecular Microbiology Washington University in St. Louis School of Medicine St. Louis Missouri U.S.A.
authors.forename: Joseph P
authors.initials: JP
authors.lastname: Vogel
authors.affiliation: Department of Otolaryngology Washington University in St. Louis School of Medicine St. Louis Missouri U.S.A.
authors.forename: Richard
authors.initials: R
authors.lastname: Chole
keywords: D‐amino acids; P. aeruginosa; biofilms; chronic biofilm infections