Conjugative transposon Tn5253 of Streptococcus pneumoniae
Abstract number: P1202
Iannelli F., Santoro F., Oggioni M., Pozzi G.
Objectives: The conjugative transposon (CT) Tn5253, also called (cat tet)6001, is a genetic element which integrates at a specific site into the chromosome of Streptococcus pneumoniae. Tn5253 was originally found in S. pneumoniae strain BM6001, a serogroup 19 clinical isolate resistant to chloramphenicol and tetracycline. Tn5253 was found to carry resistance genes tet(M) and cat, and could be trasferred by conjugation to the chromosomes of other pneumococcal strains and of other bacterial species including Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus gordonii, and Enterococcus faecalis. Aim of this study was to obtain the complete nucleotide sequence of Tn5253, as a contribution to our understanding of the resistance-carrying mobile genetic elements that are found in the genomes of S. pneumoniae isolates.
Methods: The complete nucleotide sequence of Tn5253 was obtained by using as a template different PCR fragments (size varies between 0.3 to 22 kb).
Results: Sequence analysis showed that Tn5253 is 64,513 bp in size, with 78 ORFs. Tn5253 was also found to contain two distinct genetic elements integrated: (i) a copy of Tn5251, of the Tn916-Tn1545 family of tet(M)-carrying CT, and (ii) a copy of pC194, a cat-containing plasmid of Staphylococcus aureus. Tn5251 was found to be 18,039 bp in size and 99% identical to Tn916 of Enterococcus faecalis. The copy of pC194 found in Tn5253 (called pC1945253) was 2816 bp in size and, compared to pC194, had a deletion of 93 bp involving the plasmid replication origin. Conclusion.
These data represent the basis for a detatiled analysis of the repertoire of mobile genetic elements in Streptococcus pneumoniae, and for a functional analysis of the conjugation properties of this element.
|Session name:||18th European Congress of Clinical Microbiology and Infectious Diseases|
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