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In vitro development of chlorhexidine resistance in Streptococcus sanguis and its transmissibility by genetic
Abstract:
Three chlorhexidine-sensitive strains of Streptococcus sanguis developed resistance to chlorhexidine when grown as continuous cultures in a fermenter containing medium with increasing concentrations of the drug. The MIC of the test strains increased by between two and three dilution steps and these high values were maintained after daily transfer in drug-free medium for at least 15 d. In addition, the resistance of one of the strains persisted for more than 1 month of continuous growth in drug-competent sensitive S. sanguis to increased chlorhexidine resistance, thus proving that resistance to this drug is an inheritable trait. Immunoelectrophoretic experiments showed that certain changes in the antigenic pattern of the Chxr variants had occurred as compared with their sensitive wild-type strains. Antigenic extracts of the Chxr variants and all Chxr recombinants tested contained consistently less protein than those of the sensitive wild-types.
Insights
Streptococcus sanguis developed chlorhexidine resistance through continuous culture. This acquired resistance is an inheritable trait, with altered antigenic patterns observed in resistant strains.
Area of Science:
- Microbiology
- Antimicrobial Resistance
Background:
- Chlorhexidine is a widely used antiseptic.
- Understanding the development of antimicrobial resistance is crucial for public health.
Purpose of the Study:
- To investigate the development and heritability of chlorhexidine resistance in Streptococcus sanguis.
- To analyze changes in antigenic patterns associated with chlorhexidine resistance.
Main Methods:
- Continuous culture of Streptococcus sanguis in increasing chlorhexidine concentrations.
- Determination of Minimum Inhibitory Concentration (MIC).
- Immunoelectrophoresis to analyze antigenic variations.
Main Results:
- Three strains of Streptococcus sanguis developed significant chlorhexidine resistance.
- Resistance was maintained after prolonged drug-free cultivation, indicating heritability.
- Resistant variants exhibited altered antigenic profiles and reduced protein content in extracts.
Conclusions:
- Streptococcus sanguis can acquire inheritable resistance to chlorhexidine.
- Antigenic changes are associated with the development of chlorhexidine resistance.
- Further research into the mechanisms of resistance and antigenic alterations is warranted.