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Presence of a small plasmid in clinical isolates of Streptococcus pneumoniae
Abstract:
We have detected the presence of a small (2.95 kb) plasmid in a clinical isolate of Streptococcus pneumoniae. A restriction map was constructed for this plasmid and for pDP1 (the only previously reported pneumococcal plasmid); no apparent differences were observed and the two plasmids hybridized strongly to each other. Portions of pDP1 were then cloned into Escherichia coli K-12, using the vector pUC19, and the pneumococcal DNA insert was used as a probe to screen 500 clinical isolates of S. pneumoniae for pDP1 sequences. The plasmid was detected in a total of 8 isolates. These were of various serotypes and no correlation could be found between the presence of the plasmid and the geographical location from which it came, the type of infection, or with resistance to antibacterial drugs. Although no function has yet been assigned to pDP1, it may form the basis of a useful vector for cloning in S. pneumoniae, as it contains at least seven unique restriction sites.
Insights
A small plasmid, similar to the previously reported pDP1, was found in 8 clinical Streptococcus pneumoniae isolates. This discovery suggests pDP1 may be a useful cloning vector for S. pneumoniae research.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Plasmids are extrachromosomal DNA elements that can confer advantageous traits to bacteria.
- The characterization of plasmids in Streptococcus pneumoniae is crucial for understanding bacterial adaptation and developing novel genetic tools.
- Previously, only one pneumococcal plasmid, pDP1, had been reported.
Purpose of the Study:
- To investigate the presence and characteristics of plasmids in clinical isolates of Streptococcus pneumoniae.
- To compare a newly detected plasmid with the known pneumococcal plasmid pDP1.
- To assess the potential of pDP1 as a cloning vector for S. pneumoniae.
Main Methods:
- Plasmid DNA isolation from a clinical isolate of Streptococcus pneumoniae.
- Restriction mapping and DNA hybridization to compare plasmids.
- Cloning of plasmid fragments into Escherichia coli using the pUC19 vector.
- Screening of 500 clinical S. pneumoniae isolates using a DNA probe derived from pDP1.
Main Results:
- A small (2.95 kb) plasmid was detected in a clinical isolate of Streptococcus pneumoniae.
- The detected plasmid showed no apparent differences from pDP1 and hybridized strongly to it.
- The pDP1 sequence was found in 8 out of 500 screened isolates, with no correlation to serotype, infection type, or drug resistance.
- The plasmid pDP1 contains at least seven unique restriction sites, indicating potential for cloning.
Conclusions:
- The plasmid pDP1 is present in a subset of clinical Streptococcus pneumoniae isolates.
- The prevalence and distribution of pDP1 do not appear to be linked to specific serotypes, infection types, or antibiotic resistance.
- The unique restriction sites within pDP1 suggest its utility as a potential cloning vector for genetic manipulation in S. pneumoniae.