Periodontal disease associated microbiota before and after antimicrobial therapy Metagenome

Antibiotic treatment in periodontal patients is typically selected empirically or by using qPCR or DNA hybridization methods. These molecular approaches are directed toward establishing the levels of different periodontal pathogens in samples from periodontal pockets and using those to infer the antibiotic treatment with potentially best efficacy. However, current methods are costly and do not consider the antibiotic susceptibility of the whole subgingival biofilm. In the current manuscript, we have developed a method to culture subgingival samples ex vivo in a fast, label-free impedance-based system where biofilm growth is monitored in real-time under exposure to different antibiotics, producing results in less than 4 hours. We have also performed a double-blind, randomized clinical trial where patients with chronic periodontitis were randomly treated with an antibiotic to either selected by the (n=32)DNA hybridization method (n=32) or the one indicated by the impedance system. The antibiotic selection did not coincide in both methods in 81.9% of the cases. Evaluation of clinical parameters such as periodontal pocket depth, clinical attachment level, bleeding upon probing and plaque presence showed that the group treated with antibiotics selected by impedance measurements showed a decrease in all of these parameters Moreover, 16s rRNA gene sequencing showed the extent reduction in periodontal pathogens and increase in health-associated bacteria after treatment. We hypothesize that the disagreements with DNA-based molecular methods stem from the polymicrobial nature of periodontal disease giving rise to multiple interactions and unpredictable antibiotic susceptibility, as well as from intra-specific variability in antibiotic susceptibility. Thus, the analysis of clinical outcomes and microbiological features together with the reduced cost and low analysis time supports the use of ex vivo culture methods for improved individualized antibiotic selection.