Detection of Biofilm Production of Yersinia enterocolitica Strains Isolated from Infected Children and Comparative Antimicrobial Susceptibility of Biofilm Versus Planktonic Forms
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Background and Objectives
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.
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.
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.
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.
KeywordsAntimicrobial Susceptibility Netilmicin Yersinia Enterocolitica Clinical Laboratory Standard Institute Planktonic Form
This study was financially supported by the Aeginition Hospital of the Athens Medical School of the National and Kapodistrian University (Athens, Greece). We thank Dr. Eleftheria Trikka-Grafakos, Head of the Department of Clinical Microbiology of the Thriassio General Hospital of Elefsina in Attica Greece, for providing us with the collection of the bacterial clinical isolates.
The authors have no conflicts of interest that are directly relevant to the content of this study.
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