Crystalline biofilm produced by Proteus mirabilis: an overview on their formation assays and antimicrobials interaction
Al- Anbar Medical Journal,
2008, Volume 6, Issue 1, Pages 33-42
AbstractAbstract:Objective: The aim of this study was to detect biofilm formation by study isolates of Proteus mirabilis qualitatively and quantitatively. Furthermore, depending on minimal inhibitory concentration (MICs) value and in term of biofilm inhibitory concentration (BIC) and minimal biofilm eradication concentration (MBEC), biofilm antimicrobial susceptibility test for selected antimicrobial agents against the study isolates was detected. Patients and methods: Qualitative biofilm formation assays (tube method and Foley-catheter assay) and quantitative assay by spectrophotometric method with ELISA reader were achieved against 15 isolates of Proteus mirabilis. Planktonic and biofilm antimicrobial susceptibility tests were performed.Results: Out of 15 isolates of Proteus mirabilis, biofilms were produced in all these isolates (100%) in both of tube and Foley-catheter method. In the spectrophotometric method, our results showed that, all study isolates produced biofilm strongly in the glucose-supplemented media. Our result showed that minimal inhibitory concentrations were 12.5 ±10.1 µg/ml, 46.4 ±23.7 µg/ml and 9.6 ±3.3 µg/ml for ciprofloxacin, piperacillin and amikacin respectively against logarithmic phase planktonic cells of Proteus mirabilis. Also, biofilm inhibitory concentrations and minimal biofilm eradication concentrations for selected antimicrobial agents were reached 50-100 X folds higher than MICs to inhibit and eradicate Proteus mirabilis biofilm. Conclusion: It is suggested that biofilm production was affected by the presence of glucose in the culture media. Furthermore, in biofilm antimicrobial susceptibility test, the biofilm producer isolates of Proteus mirabilis required 50-100 X folds higher than MIC for the same isolates at planktonic state to inhibit and eradicate bacterial biofilm from the surface of catheters. Key words: Crystalline biofilm, formation, antimicrobial interaction.
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