Tn5406, a new staphylococcal transposon conferring resistance to streptogramin a and related compounds including dalfopristin.
We characterized a new transposon, Tn5406 (5,467 bp), in a clinical isolate of Staphylococcus aureus (BM3327). It carries a variant of vgaA, which encodes a putative ABC protein conferring resistance to streptogramin A but not to mixtures of streptogramins A and B. It also carries three putative genes, the products of which exhibit significant similarities (61 to 73% amino acid identity) to the three transposases of the staphylococcal transposon Tn554. Like Tn554, Tn5406 failed to generate target repeats. In BM3327, the single copy of Tn5406 was inserted into the chromosomal att554 site, which is the preferential insertion site of Tn554. In three other independent S. aureus clinical isolates, Tn5406 was either present as a single plasmid copy (BM3318), as two chromosomal copies (BM3252), or both in the chromosome and on a plasmid (BM3385). The Tn5406-carrying plasmids also contain two other genes, vgaB and vatB. The insertion sites of Tn5406 in BM3252 were studied: one copy was in att554, and one copy was in the additional SCCmec element. Amplification experiments revealed circular forms of Tn5406, indicating that this transposon might be active. To our knowledge, a transposon conferring resistance to streptogramin A and related compounds has not been previously described.
Staphylococci Unit, Institut Pasteur, 25/28 Rue du Doctor Roux, 75724 Paris Cedex 15, France.
Julien
J
Haroche
Jeanine
J
Allignet
Névine
N
El Solh
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002876:Chromosomes, Bacterial / Q000235:genetics; D003001:Cloning, Molecular; D003470:Culture Media; D004251:DNA Transposable Elements / Q000235:genetics; D004269:DNA, Bacterial / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D005798:Genes, Bacterial / Q000235:genetics*; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data; D010957:Plasmids / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000235:genetics*; D025364:Streptogramin A / Q000494:pharmacology*; D014769:Virginiamycin / Q000031:analogs & derivatives* / Q000494:pharmacology*
D000900:Anti-Bacterial Agents; D003470:Culture Media; D004251:DNA Transposable Elements; D004269:DNA, Bacterial; D014769:Virginiamycin; D025364:Streptogramin A; C113826:dalfopristin