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17-03-2013 | Infectious disease | Article

Tooth extraction unleashes diverse bacteremia


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medwireNews: Dental extractions are followed by transient bacteremia that is characterized by "extraordinarily" high bacterial diversity, a study by Spanish researchers reveals.

The team calls for the viability and potential pathogenicity of this diverse microbiota to be studied further in order to improve the diagnosis and treatment of post-extraction infections, particularly in immunocompromised patients.

Inmaculada Tomás (Santiago de Compostela University) and team studied eight patients undergoing dental extractions under general anesthesia. Peripheral venous blood samples were collected at baseline, 30 seconds, and 15 minutes after the procedure.

The samples were analyzed for bacteremia using conventional culture-dependent methods and with pyrosequencing using universal bacterial primers that target the 16S ribosomal DNA gene.

Writing in PLoS ONE, the team reports that conventional methods detected bacteremia in one sample at baseline, in all eight samples at 30 seconds, and in six samples at 15 minutes after dental extraction.

With 16S pyrosequencing, bacteremia was detected in no samples at baseline, in five samples at 30 seconds, and in no samples at 15 minutes.

With regard to the diversity of bacteria, conventional culture-based methods detected a single microbial species in six patients and two species in two patients. The most prevalent isolates were Streptococcus viridians, followed by Peptoniphilus assaccharolyticus, Gemella spp., and Actinomyces spp.

By contrast, 16S pyrosequencing identified many more isolates, at an average of 13.4 distinct bacterial families and 22.8 genera per sample. Unexpectedly, the most frequent bacteria were from the Methylobacteriaceae family, which were found in 21.5% of samples.

Other bacteria frequently detected with 16S pyrosequencing were the Comamonadaceae family and the Actinobacteria class (Actinomycetaceae, Corynebacteriaceae, Propionibacteriaceae, and Micrococcaceae families). Less common isolates were from the Fusobacteriaceae, Veillonellaceae, and TM7 families of bacteria.

Tomás et al conclude that while 16S pyrosequencing underestimates the prevalence and duration of bacteremia following dental extraction, the technique nevertheless reveals a "dramatically" greater bacterial diversity than that seen with culture methods.

This new information could be especially critical for immunocompromised patients requiring oral surgical procedures, they remark. Thus, culture and molecular techniques "must be jointly used to better diagnose and prevent focal infections of oral origin especially in immunocompromised patients," they conclude.

By Joanna Lyford, Senior medwireNews Reporter

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