Detection of transient bacteraemia following dental extractions by 16S rDNA pyrosequencing: a pilot study

Abstract

Objective:The current manuscript aims to determine the prevalence, duration and bacterial diversity of bacteraemiafollowing dental extractions using conventional culture-dependent methods and 16S rDNA pyrosequencing.Methods:The study group included 8 patients undergoing dental extractions under general anaesthesia. Peripheral venousblood samples were collected at baseline, 30 seconds and 15 minutes after the dental extractions. Blood samples wereanalysed for bacteraemia applying conventional microbiological cultures under aerobic and anaerobic conditions as well aspyrosequencing using universal bacterial primers that target the 16S ribosomal DNA gene.Results:Transient bacteremia was detected by culture-based methods in one sample at baseline time, in eight samples at30 seconds, and in six samples at 15 minutes after surgical procedure; whereas bacteraemia was detected only in five bloodsamples at 30 seconds after dental extraction by using pyrosequencing. By applying conventional microbiological methods,a single microbial species was detected in six patients, andStreptococcus viridanswas the most frequently culturedidentified bacterium. By using pyrosequencing approaches however, the estimated blood microbial diversity after dentalextractions was 13.461.7 bacterial families and 22.861.1 genera per sample.Conclusion:The application of 16S rDNA pyrosequencing underestimated the prevalence and duration of bacteraemiafollowing dental extractions, presumably due to not reaching the minimum DNA required for PCR amplification. However,this molecular technique, unlike conventional culture-dependent methods, revealed an extraordinarily high bacterialdiversity of post-extraction bacteraemia. We propose that microorganisms recovered by culture may be only the tip of aniceberg of a really diverse microbiota whose viability and potential pathogenicity should be further studied.