Jaffray, E.C.; (2006) Characterisation of paediatric odontogenic bacteraemia. Doctoral thesis , University of London.

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Abstract

Transient, asymptomatic bacteraemia can occur following dental extraction. Such events may lead to the development of serious systemic disease including infective endocarditis and abscesses of the brain and other organs. The aims of this PhD were to establish the prevalence, intensity, duration and microbiota involved in dental bacteraemia. Blood was sampled from 500 children before and after extraction post-extraction samples were taken at randomly allocated time intervals ranging from 10 seconds to 1 hour following treatment. Post-extraction bacteraemia was found to be most prevalent at 1 minute post-extraction with 76% of samples being culture-positive. Bacteraemia was low grade, with greatest intensity at 1 minute post-extraction with a range of 0.17 to 40.83 cfu/mL detected. The majority of isolates recovered were typical oral microbiota, most prevalent were streptococci and Actinomyces spp. Bacteraemia was judged to be resolved between 7.5 and 15 minutes post- extraction. Identification of streptococci, especially those related to the mitis group species proved difficult. Streptococci were identified using a polyphasic approach, including comparative 16S rRNA gene sequencing, biochemical testing and the development of a sodA PCR-RFLP method. The sodA PCR-RFLP method was found to identify 71.7% of the isolates to species level compared to only 55.1% using 16S sequencing. Two hundred and twenty eight isolates from 121 subjects were assayed for resistance to five antibiotics: ampicillin, erythromycin, penicillin, tetracycline and vancomycin. Thirty one percent showed resistance to at least 1 antibiotic at the break-point concentrations used, with some isolates displaying resistance to 4 of the antibiotics tested. The use of molecular techniques for investigation of bacteraemia was evaluated. Detection limits for Gram-positive and Gram-negative isolates and the effect of inherent PCR inhibitors were investigated. It is hoped that this work will promote the understanding of bacteraemia following dental extraction and provide more information to clinicians assessing the risk of focal infection.

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