Ex vivo evaluation of antibiotic sensitivity in samples from endodontic infections

ABSTRACT

Objective

To develop an in vitro model for real-time monitoring of endodontic biofilm growth and evaluate the ex vivo effect of antibiotics on biofilm growth.

Material and Methods

Root canal samples were taken from 40 patients and inoculated into 96-well plates in a system that measures biofilm growth through electrical impedance. Biofilm bacterial composition at the genus and species level was analyzed by Illumina sequencing. ANCOM-BC corrected data were used to compare bacterial composition after antibiotic treatment through compositional analysis, and to compare microbiological with clinical data.

Results

The stationary phase was reached at 8 hours. The biofilm formed had a similar bacterial composition to the inoculum, and Enterococcus faecalis was virtually absent from the samples. The bacterial composition and the effect of antibiotics were sample-dependent. Metronidazole was the antibiotic that most inhibited biofilm formation and azithromycin the one that inhibited it in the highest percentage of cases. The antibiotic effect could not be related to the biofilm original bacterial composition.

Conclusions

The impedance system allowed real-time monitoring of endodontic biofilm formation, and we propose it as a model for ex vivo evaluation of the whole biofilm susceptibility to antimicrobials, as opposed to evaluating antibiotic sensitivity of specific bacterial isolates.

KEYWORDS:

• Antibiotic
• biofilm
• biofilm model
• endodontic
• real time cell analysis

Acknowledgements

The 96X E-plate microtiter plates were kindly provided by ACEA Biosciences®. We thank Dr Paredes for her participation in the sample collection process and Sandra García Esteban and Mª Dolores Catalán for their help with DNA extraction and sequencing. We also thank Alejandro Artacho for his help with statistical analysis.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplemental data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/20002297.2022.2160536

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This work was supported by the Spanish Ministry of Science, Innovation and Universities grant # RTI2018-102032-B-I00 to AM.