Electrophoresis of whole-cell soluble proteins of microorganisms isolated from bacteremias in endodontic therapy.

We have previously demonstrated that anaerobic bacteria are the microorganisms most frequently isolated from blood following endodontic therapy of teeth with apical periodontitis. Phenotypic characterisation of the isolates suggested that the bacteria in the blood originated from the root canal. The present experiment using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) was carried out in an effort to verify these findings, and to further study the microorganisms involved in endodontic bacteremias. Soluble cellular proteins were extracted from 11 reference strains and 26 bacterial isolates recovered from the root canal and blood. These included Propionibacterium acnes, Peptostreptococcus prevotii, Fusobacterium nucleatum, Prevotella intermedia. Actinomyces israelii, Streptococcus intermedius, Streptococcus sanguis. The electrophoretic patterns mostly confirmed the identity of the isolates as determined by the biochemical and antimicrobial resistance tests. Furthermore, with this typing method the species Prevotella intermedia and Prevotella nigrescens could be differentiated. These species had been recovered from both root canal and blood. Also, differences between subspecies of Fusobacterium nucleatum became evident with SDS-PAGE, and the results indicated that the organism recovered from the root canal and blood was Fusobacterium nucleatum subsp. vincentii. The electrophoretic patterns of the different organisms isolated from the root canal and the blood were similar, providing further evidence that the bacteria found in the blood originated from the root canal.