The Bead Assay for Biofilms: A Quick, Easy and Robust Method for Testing Disinfectants.
Bacteria live primarily in microbial communities (biofilms), where they exhibit considerably higher biocide tolerance than their planktonic counterparts. Current standardized efficacy testing protocols of disinfectants, however, employ predominantly planktonic bacteria. In order to test the efficacy of biocides on biofilms in a standardized manner, a new assay was developed and optimized for easy-handling, quickness, low running costs, and above all-repeatability. In this assay, 5 mm glass- or polytetrafluoroethylene beads in 24 well microtiter plates served as substrate for Pseudomonas aeruginosa biofilms. After optimizing result-relevant steps, the actual performance of the assay was explored by treating P. aeruginosa biofilms with glutaraldehyde, isopropanol, or peracetic acid in predefined concentrations. The aspired 5 log10 reduction in CFU counts was achieved by glutaraldehyde at 5% (30 min), and by peracetic acid at 0.3% (10 min). In contrast, 80% isopropanol (30 min) failed to meet the reduction goal. However, the main accomplishment of this study was to unveil the potential of the array itself; most noteworthy here, a reliable repeatability of the results. The new bead assay for biofilms is a robust, quick and cost-effective method for assessing the efficacy of biocides against biofilms.
Division for applied Infection Control and Hospital Hygiene, Robert Koch Institute, Berlin, Germany.|Advanced Light and Electron Microscopy, Robert Koch Institute, Berlin, Germany.
Katharina
K
Konrat
Division for applied Infection Control and Hospital Hygiene, Robert Koch Institute, Berlin, Germany.
Ingeborg
I
Schwebke
Advanced Light and Electron Microscopy, Robert Koch Institute, Berlin, Germany.
Michael
M
Laue
Advanced Light and Electron Microscopy, Robert Koch Institute, Berlin, Germany.
Christin
C
Dittmann
Division for applied Infection Control and Hospital Hygiene, Robert Koch Institute, Berlin, Germany.
Katja
K
Levin
Division for applied Infection Control and Hospital Hygiene, Robert Koch Institute, Berlin, Germany.
Ricarda
R
Andrich
Division for applied Infection Control and Hospital Hygiene, Robert Koch Institute, Berlin, Germany.
Mardjan
M
Arvand
Advanced Light and Electron Microscopy, Robert Koch Institute, Berlin, Germany.
Christoph
C
Schaudinn
D019840:2-Propanol / Q000494:pharmacology; D018441:Biofilms / Q000187:drug effects* / Q000254:growth & development; D004202:Disinfectants / Q000494:pharmacology*; D005976:Glutaral / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D010463:Peracetic Acid / Q000494:pharmacology; D011138:Polytetrafluoroethylene / Q000737:chemistry; D011550:Pseudomonas aeruginosa / Q000187:drug effects* / Q000472:pathogenicity
D004202:Disinfectants; D011138:Polytetrafluoroethylene; D010463:Peracetic Acid; D019840:2-Propanol; D005976:Glutaral