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Paper point transfer of minimal numbers of microorganisms from a prepared canal in vitro
Abstract:
A strain of Str. faecalis resistant to 2 mg./c.c. streptomycin was developed, and serial dilutions of known quantities of the organism were introduced into prepared root canals of extracted teeth. The canals were cultured with sterile dry paper points, incubated in tubes of thioglycollate media containing 2 mg./c.c. streptomycin at 37 degrees C. These tubes were checked for growth at 24-hour intervals for 7 days. Some tubes yielded growth on the first day, while those with greater dilutions of sample took 7 days. All samples with bacteria did yield growth by the seventh day. At the time of transfer of the organism into the prepared root canals, an identical sample of suspended organisms were spread on pour plates of brain-heart infusion broth containing 2 mg./c.c. streptomycin. After incubation at 37 degrees C. for 24 hours, the numbers of colonies were counted in order to determine the exact number of organisms in each serial dilution. Taking a culture after introduction of sterile distilled water into a canal and evaluation of the culture at the time of the scheduled filling appointment are recommended clinical procedures.
Insights
This study shows that even high dilutions of streptomycin-resistant Enterococcus faecalis bacteria will grow in root canals within seven days. This highlights the need for effective disinfection protocols in endodontic treatment.
Area of Science:
- Microbiology
- Endodontics
- Infectious Diseases
Background:
- Root canal infections are a common cause of endodontic failure.
- Enterococcus faecalis is a frequently isolated bacterium from persistent root canal infections.
- Antibiotic resistance in endodontic pathogens poses a clinical challenge.
Purpose of the Study:
- To evaluate the viability and growth of streptomycin-resistant Enterococcus faecalis in prepared root canals.
- To determine the time course of bacterial growth from various dilutions in a simulated root canal environment.
- To assess the efficacy of current methods in detecting bacterial presence after treatment.
Main Methods:
- A streptomycin-resistant strain of Enterococcus faecalis was developed.
- Serial dilutions of the organism were inoculated into prepared root canals of extracted teeth.
- Cultures were taken using paper points and incubated in thioglycollate media with streptomycin.
- Bacterial growth was monitored over seven days at 24-hour intervals.
- Initial bacterial concentrations were quantified using pour plates.
Main Results:
- All inoculated root canals showed bacterial growth within seven days, regardless of initial dilution.
- Samples with higher bacterial dilutions required the full seven days for observable growth.
- The pour plate method confirmed the initial bacterial load in each dilution.
Conclusions:
- Streptomycin-resistant Enterococcus faecalis can persist and grow in root canals even after simulated treatment.
- Standard culturing methods can detect bacterial presence up to seven days post-inoculation.
- Clinical recommendations include post-treatment culturing to ensure canal disinfection before filling.