Affiliation:
1. Unité des Agents Antibactériens, Institut Pasteur, 75724 Paris Cedex 15, France
Abstract
ABSTRACT
We determined the sequence and genetic organization of plasmid pIP823, which contains the
dfrD
gene;
dfrD
confers high-level trimethoprim resistance to
Listeria monocytogenes
BM4293 by synthesis of dihydrofolate reductase type S2. pIP823 possessed all the features of the pUB110/pC194 plasmid family, whose members replicate by the rolling-circle mechanism. The
rep
gene encoded a protein identical to RepU, the protein required for initiation of the replication of plasmids pTB913 from a thermophilic
Bacillus
sp. and pUB110 from
Staphylococcus aureus
. The
mob
gene encoded a protein with a high degree of amino acid identity with the Mob proteins involved in conjugative mobilization and interplasmidic recombination of pTB913 and pUB110. The host range of pIP823 was broad and included
L. monocytogenes
,
Enterococcus faecalis
,
S. aureus
,
Bacillus subtilis
, and
Escherichia coli
. In all these species, pIP823 replicated by generating single-stranded DNA and was stable. Conjugative mobilization of pIP823 was obtained by self-transferable plasmids between
L. monocytogenes
and
E. faecalis
, between
L. monocytogenes
and
E. coli
, and between strains of
E. coli
, and by the streptococcal conjugative transposon Tn
1545
from
L. monocytogenes
to
E. faecalis
, and from
L. monocytogenes
and
E. faecalis
to
E. coli
. These data indicate that the gene flux observed in nature from gram-positive to gram-negative bacteria can occur by conjugative mobilization. Our results suggest that dissemination of trimethoprim resistance in
Listeria
spp. and acquisition of other antibiotic resistance determinants in this species can be anticipated.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Cited by
54 articles.
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