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Transformation as a tool for studying the epidemiology of tet determinants in Streptococcus pneumoniae
Abstract:
Transformation of pneumococcus was used to detect homology among tetracycline resistance determinants of clinical isolates of Streptococcus pneumoniae. A strain of pneumococcus containing a mutated tet determinant (tet-3), of class M, integrated into the chromosome was used as a recipient in transformation experiments, where donor DNA was from the tetracycline resistant isolates. 34/34 strains appeared to have tet determinants homologous to tet-3 (i.e. tet M). Still using transformation it was possible to determine that the tet-3 transforming activity of DNA from Tn916 and S. pneumoniae BM6001 was contained in a 5 kb HincII fragment. For this purpose a transformation technique where donor DNA was directly taken from low melting point agarose gels was standardized and used.
Insights
This study found that all tested Streptococcus pneumoniae isolates contain tetracycline resistance genes homologous to tet-3 (tetM). Transformation experiments pinpointed the tet-3 resistance determinant to a specific DNA fragment.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Tetracycline resistance is a significant concern in clinical Streptococcus pneumoniae isolates.
- Understanding the genetic basis of tetracycline resistance is crucial for combating antibiotic resistance.
Purpose of the Study:
- To investigate the homology of tetracycline resistance determinants in clinical Streptococcus pneumoniae isolates.
- To identify the specific DNA fragment responsible for tetracycline resistance (tet-3) transforming activity.
Main Methods:
- Bacterial transformation experiments using a mutated pneumococcal strain (tet-3) as a recipient.
- Donor DNA was derived from tetracycline-resistant clinical isolates of Streptococcus pneumoniae.
- Standardization of a transformation technique using DNA directly from low melting point agarose gels.
Main Results:
- All 34 tested clinical isolates of Streptococcus pneumoniae possessed tetracycline resistance determinants homologous to tet-3 (tetM).
- The tet-3 transforming activity from Tn916 and S. pneumoniae BM6001 was localized to a 5 kb HincII fragment.
Conclusions:
- The tetM determinant is highly conserved among clinical isolates of Streptococcus pneumoniae.
- Transformation assays effectively identified homologous resistance genes and localized specific DNA fragments conferring resistance.