Comparison of sonication with chemical biofilm dislodgement methods using chelating and reducing agents: Implications for the microbiological diagnosis of implant associated infection

• Published in: PloS one Vol. 15; no. 4; p. e0231389
• Main Authors: Karbysheva, Svetlana, Di Luca, Mariagrazia, Butini, Maria Eugenia, Winkler, Tobias, Schütz, Michael, Trampuz, Andrej
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 08.04.2020; Public Library of Science (PLoS)
• Subjects: Acetic acid; Bacteria; Beads; Biofilms; Biology and Life Sciences; Chelating agents; Chelation; Chemical activity; Chemical agents; Chemical weapons; Colonies; Comparative analysis; Counting; Diagnosis; Digital television; Dithiothreitol; E coli; Edetic acid; EDTA; Electron microscopy; Engineering and Technology; Escherichia coli; Ethylenediaminetetraacetic acids; Future predictions; Glass beads; Health aspects; Hypothesis testing; Infection; Infections; Medical diagnosis; Medicine and Health Sciences; Methods; Microbiology; Microorganisms; Microscopy; Pseudomonas aeruginosa; Qualitative analysis; Reducing agents; Research and Analysis Methods; Scanning electron microscopy; Sodium chloride; Sonication; Standard deviation; Staphylococcus aureus; Staphylococcus epidermidis; Staphylococcus infections; Surgery; Transplants & implants; Germany; St Louis Missouri; United States > US
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0231389

The diagnosis of implant-associated infections is hampered due to microbial adherence and biofilm formation on the implant surface. Sonication of explanted devices was shown to improve the microbiological diagnosis by physical removal of biofilms. Recently, chemical agents have been investigated for biofilm dislodgement such as the chelating agent ethylenediaminetetraacetic acid (EDTA) and the reducing agent dithiothreitol (DTT). We compared the activity of chemical methods for biofilm dislodgement to sonication in an established in vitro model of artificial biofilm. Biofilm-producing laboratory strains of Staphylococcus epidermidis (ATCC 35984), S. aureus (ATCC 43300), E. coli (ATCC 25922) and Pseudomonas aeruginosa (ATCC 53278) were used. After 3 days of biofilm formation, porous glass beads were exposed to control (0.9% NaCl), sonication or chemical agents. Quantitative and qualitative biofilm analyses were performed by colony counting, isothermal microcalorimetry and scanning electron microscopy. Recovered colony counts after treatment with EDTA and DTT were similar to those after exposure to 0.9% NaCl for biofilms of S. epidermidis (6.3 and 6.1 vs. 6.0 log10 CFU/mL, S. aureus (6.4 and 6.3 vs. 6.3 log10 CFU/mL), E. coli (5.2 and 5.1 vs. 5.1 log10 CFU/mL and P. aeruginosa (5.1 and 5.2 vs. 5.0 log10 CFU/mL, respectively). In contrast, with sonication higher CFU counts were detected with all tested microorganisms (7.5, 7.3, 6.2 and 6.5 log10 CFU/mL, respectively) (p <0.05). Concordant results were observed with isothermal microcalorimetry and scanning electron microscopy. In conclusion, sonication is superior to both tested chemical methods (EDTA and DTT) for dislodgement of S. epidermidis, S. aureus, E. coli and P. aeruginosa biofilms. Future studies may evaluate potential additive effect of chemical dislodgement to sonication.