Evaluation of a nonthermal plasma needle to eliminate ex vivo biofilms in root canals of extracted human teeth

AIM

To evaluate the efficacy of a nonthermal plasma (NTP) at atmospheric pressure on ex vivo biofilm in root canals of extracted teeth.

METHODOLOGY

Intracanal contents from three teeth with root canal infections were collected, pooled and grown in thirty-five microCT-mapped root canals of extracted and instrumented human teeth. One group of teeth was treated with NTP, another with 6% NaOCl and one set was left untreated. The intracanal contents from twenty-seven teeth (nine teeth in each group) were plated on agar and colony forming units were determined. Parametric test of one-way analysis of variance (anova) was used to analyse statistical significance. The remaining teeth were cut open, stained with LIVE/DEAD(®) and examined with confocal laser scanning microscopy.

RESULTS

The untreated root canals were covered with biofilm of varying thickness. Treatment with nonthermal plasma decreased the number of viable bacteria in biofilms by one order of magnitude, whilst the NaOCl control achieved a reduction of more than four magnitudes. Both the NTP and the NaOCl treatment results were significantly different from the negative control (P < 0.05).

CONCLUSION

The nonthermal plasma displayed antimicrobial activity against endodontic biofilms in root canals, but was not as effective as the use of 6% NaOCl.

Possible role of biofilm in fulminant meningitis related to cochlear implantation of dysplastic inner ear

Thanks to improvements in device design and surgical procedures, the number of potential candidates for cochlear implantation has been growing to include patients with inner ear malformations. Many precautions are taken pre-, peri- and postoperatively for these patients given the increased risk of surgical and medical complications, but with the rising bacterial resistance to antibiotics and the discovery of biofilm as a probable cause of chronic infections, postoperative morbidity remains higher than desired.

OBJECTIVE

The purpose of this investigation is to describe histological findings on a temporal bone from a 2-year-old infant with a cochlear implant and an inner ear deformity who died of bacterial meningitis.

MATERIALS AND METHODS

The patient's temporal bone was studied under light microscopy, the cochlear implant studied with a scanning electron microscope, and later subjected to in situ hybridization to find bacterial DNA.

RESULTS

The scanning electron microscopy image shows cellular formations on the surface of the implant, which later binds to the probe used for the in situ hybridization.

CONCLUSION

There is evidence that bacterial DNA is present on the electrode array, which suggests existence of biofilm formation on the cochlear implant surface.

Characterization of enterocoliticin, a phage tail-like bacteriocin, and its effect on pathogenic Yersinia enterocolitica strains

Yersinia enterocolitica 29930 (biogroup 1A; serogroup O:7,8) produces a bacteriocin, designated enterocoliticin, that shows inhibitory activity against enteropathogenic strains of Y. enterocolitica belonging to serogroups O:3, O:5,27 and O:9. Enterocoliticin was purified, and electron micrographs of enterocoliticin preparations revealed the presence of phage tail-like particles. The particles did not contain nucleic acids and showed contraction upon contact with susceptible bacteria. Enterocoliticin addition to logarithmic-phase cultures of susceptible bacterial strains led to a rapid dose-dependent reduction in CFU. Calorimetric measurements of the heat output of cultures of sensitive bacteria showed a complete loss of cellular metabolic activity immediately upon addition of enterocoliticin. Furthermore, a dose-dependent efflux of K(+) ions into the medium was determined, indicating that enterocoliticin has channel-forming activity.