title: Detection of biofilm production of Yersinia enterocolitica strains isolated from infected children and comparative antimicrobial susceptibility of biofilm versus planktonic forms.
abstract: OBJECTIVE
  The ability of Yersinia species to produce biofilms has not been hitherto systematically studied, although there is evidence, that Y. enterocolitica is able to form biofilms on inanimate surfaces. The present study aimed to detect the production of biofilms by 60 clinical strains of Y. enterocolitica and to compare the antimicrobial susceptibility of planktonic versus biofilm-forming bacteria.
  
  
  METHODS
  Y. enterocolitica strains were collected from stool and blood cultures collected from β-thalassaemic children, with gastroenteritis and/or septicemia. The isolated bacterial strains were grouped by biotyping and serotyping and the antimicrobial susceptibility of the planktonic forms was investigated by MIC determination. Biofilm formation was detected by the use of silicone disks and for the biofilm forming strains the minimum inhibitory concentration for bacterial regrowth (MICBR) of 11 clinically important antimicrobials was determined. The presence of the waaE, a gene reported to be related with biofilm formation was investigated in all the strains.
  
  
  RESULTS
  All of 60 strains were positive for biofilm production by the use of silicone disks. The great majority of the biofilm forms were resistant to all the antimicrobials. In antimicrobial concentrations far higher than the CLSI breakpoints, bacterial regrowth from the biofilms was still possible. None of the strains bore the waaE gene.
  
  
  CONCLUSIONS
  These results, indicate that biofilm formation by Y. enterocolitica might be an inherent feature. The presence of biofilms increased dramatically the MICBR in all antimicrobials. The way in which biofilms could contribute to Y. enterocolitica pathogenicity in humans is a matter needing further investigation.
authors.affiliation: Department of Nursing, Faculty of Human Movement and Quality of Life Sciences, University of Peloponnese, Orthias Artemidos and Plataion, 231 00, Sparta, Greece.
authors.forename: A
authors.initials: A
authors.lastname: Ioannidis
authors.forename: A
authors.initials: A
authors.lastname: Kyratsa
authors.forename: V
authors.initials: V
authors.lastname: Ioannidou
authors.forename: S
authors.initials: S
authors.lastname: Bersimis
authors.forename: S
authors.initials: S
authors.lastname: Chatzipanagiotou
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001426:Bacterial Proteins / Q000235:genetics; D018441:Biofilms / Q000187:drug effects; D002675:Child, Preschool; D024881:Drug Resistance, Bacterial; D005759:Gastroenteritis / Q000382:microbiology*; D006801:Humans; D007223:Infant; D008826:Microbial Sensitivity Tests; D010933:Plankton / Q000187:drug effects; D018805:Sepsis / Q000382:microbiology*; D012703:Serotyping; D015009:Yersinia Infections / Q000382:microbiology*; D015008:Yersinia enterocolitica / Q000145:classification / Q000187:drug effects* / Q000302:isolation & purification*; D017086:beta-Thalassemia / Q000097:blood* / Q000150:complications
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins