Staphylococcus aureus is one of the most successful bacterial pathogens, harboring a vast
repertoire of virulence factors in its arsenal. As such, the genetic manipulation of S. aureus
chromosomal DNA is an important tool for the study of genes involved in virulence and
survival in the host. Previously reported allelic exchange vectors for S. aureus are shuttle
vectors that can be propagated in Escherichia coli, so that standard genetic manipulations
can be carried out. Most of the vectors currently in use carry the temperature-sensitive
replicon (pE194ts) that was originally developed for use in Bacillus subtilis. Here we show
that in S. aureus, the thermosensitivity of a pE194ts vector is incomplete at standard nonpermissive
temperatures (42 °C), and replication of the plasmid is impaired but not abolished.
We report rpsL-based counterselection vectors, with an improved temperature-sensitive
replicon (pT181 repC3) that is completely blocked for replication in S. aureus at nonpermissive
and standard growth temperature (37 °C).We also describe a set of temperaturesensitive
vectors that can be cured at standard growth temperature. These vectors provide
highly effective tools for rapidly generating allelic replacement mutations and curing expression
plasmids, and expand the genetic tool set available for the study of S. aureus.