Trimethoprim resistance determinants encoding a dihydrofolate reductase in clinical isolates of Staphylococcus aureus and coagulase-negative staphylococci
Correspondence and requests for offprints should be sent to Dr R. A. Skurray, Department of Microbiology, Monash University, Clayton, Victoria, 3168, Australia.
The molecular and biochemical basis of resistance to high concentrations (MIC ± 1000 mg/L) of trimethoprim (Tpr(h)) was examined in Australian isolates of Staphylococcus aureus and coagulase-negative staphylococci. The Tpr(h) determinant (dfrA) was located within a 2.75-Kb Bg/II fragment on the S. aureus aminoglycoside-resistance plasmids pSK1 and pSK16 as judged by comparative restriction mapping with two naturally-occurring variants, pSK9 and pSK14, which did not encode trimethoprim resistance. This was confirmed in DNA-DNA hybridisation experiments in which a 0.9-Kb sequence of pSK1 DNA was used as a specific probe for the Tpr
(h) gene. Plasmid DNA from three strains of coagulase-negative staphylococci, and the chromosomal material of one other isolate, were found to share homology with the probe DNA. Dihydrofolate reductases produced by these strains were virtually identical to the type S1 enzyme encoded by the S. aureus plasmid pSK1. Interspecies transfer may have been responsible for the conservation of Tpr(h) gene sequences among staphylococci.
AmyesS. G. B.,
SmithJ. T.1974; R-factor trimethoprim resistance mechanism: an insusceptible target site. Biochemical and Biophysical Research Communications 58:412–418
BarthP. T.,
DattaN.,
HedgesR. W.,
GrinterN. J.1976; Transposition of a deoxyribonucleic acid sequence encoding trimethoprim and streptomycin resistance from R483 to other replicons. Journal of Bacteriology 125:800–810
CoughterJ. P.,
JohnstonJ. L.,
ArcherG. L.1987; Characterization of a staphylococcal trimethoprim resistance gene and its product. Antimicrobial Agents and Chemotherapy 31:1027–1032
DanielsD. L.,
SchroederJ. L.,
SzybalskiW.,
SangerF.,
BlattnerF. R.1983; A molecular map of coliphage lambda. In
HendrixR. W.
(eds) Lambda II Cold Spring Harbor Laboratory, Cold Spring Harbor; New York: pp 469–517
GillespieM. T.,
LyonB. R.,
LooL. S. L.,
MatthewsP. R.,
StewartP. R.,
SkurrayR. A.1987a; Homologous direct repeat sequences associated with mercury, methicillin, tetracycline and trimethoprim resistance determinants in Staphylococcus aureus. FEMS Microbiology Letters 43:165–171
GillespieM. T.,
LyonB. R.,
MesserottiL. J.,
SkurrayR. A.1987b; Chromosome- and plasmid-mediated gentamicin resistance in Staphylococcus aureus encoded by Tn4001. Journal of Medical Microbiology 24:139–144
GillespieM. T.,
MayJ. W.,
SkurrayR. A.1984; Antibiotic susceptibilities and plasmid profiles of nosocomial methi-cillin-resistant Staphylococcus aureus: a retrospective study. Journal of Medical Microbiology 17:295–310
Hamilton-MillerJ. M. T.,
GoodingA.,
BrumfittW.1981; Resistance to trimethoprim in 1978–79 compared with 1973-75. Journal of Clinical Pathology 34:439–442
JaffeH. W.,
SweeneyH. M.,
NathanC.,
WeinsteinR. A.,
KabinsS. A.,
CohenS.1980; Identity and interspecific transfer of gentamicin-resistance plasmids in Staphylococcus aureus and Staphylococcus epidermidis.. Journal of Infectious Diseases 141:738–747
LyonB. R.,
GillespieM. T.,
ByrneM. E.,
MayJ. W.,
SkurrayR. A.1987; Plasmid-mediated resistance to gentamicin in Staphylococcus aureus: the involvement of a transposon. Journal of Medical Microbiology 23:101–110
LyonB. R.,
IuorioJ. L.,
MayJ. W.,
SkurrayR. A.1984a; Molecular epidemiology of multiresistant Staphylococcus aureus in Australian hospitals. Journal of Medical Microbiology 17:79–89
LyonB. R.,
MayJ. W.,
SkurrayR. A.1983; Analysis of plasmids in nosocomial strains of multiple-antibiotic-resistant Staphylococcus aureus. Antimicrobial Agents and Chemotherapy 23:817–826
LyonB. R.,
MayJ. W.,
SkurrayR. A.1984b; Tn4001: a gentamicin and kanamycin resistance transposon in Staphylococcus aureus. Molecular and General Genetics 193:554–556
LyonB. R.,
TennentJ. M.,
MayJ. W.,
SkurrayR. A.1986; Trimethoprim resistance encoded on a Staphylococcus aureus gentamicin resistance plasmid: cloning and transposon mutagenesis. FEMS Microbiology Letters 33:189–192
McDonnellR. W.,
SweeneyH. M.,
CohenS.1983; Conjugational transfer of gentamicin resistance plasmids intra- and interspecifically in Staphylococcus aureus and Staphylococcus epidermidis. Antimicrobial Agents and Chemotherapy 23:151160
NaidooJ.,
NobleW. C.1981; Transfer of gentamicin resistance between coagulase-negative and coagulase-positive staphylococci on skin. Journal of Hygiene 86:183–187
RichardsonJ. F.1983; Frequency of resistance to trimethoprim among isolates of Staphylococcus epidermidis and Staphylococcus saprophyticus.. Journal of Antimicrobial Chemotherapy 11:163–167
SmithG. E.,
SummersM. D.1980; The bidirectional transfer of DNA and RNA to nitrocellulose or diazobenzyloxymethyl-paper. Analytical Biochemistry 109:123–129
TennentJ. M.,
LyonB. R.,
GillespieM. T.,
MayJ. W.,
SkurrayR. A.1985; Cloning and expression of Staphylococcus aureus plasmid-mediated quaternary ammonium resistance in Escherichia coli. Antimicrobial Agents and Chemotherapy 27:79–83
TennentJ. M.,
MayJ. W.,
SkurrayR. A.1984; Multiple antibiotic resistance in Staphylococcus aureus and Staphylococcus epidermidis: plasmids in strains associated with nosocomial infection. Pathology 16:250–255
TennentJ. M.,
MayJ. W.,
SkurrayR. A.1986; Characterisation of chloramphenicol resistance plasmids of Staphylococcus aureus and S. epidermidis by restriction enzyme mapping techniques. Journal of Medical Microbiology 22:79–84
TownsendD. E.,
AshdownN.,
GreedL. C.,
GrubbW. B.1984; Transposition of gentamicin resistance to staphylococcal plasmids encoding resistance to cationic agents. Journal of Antimicrobial Chemotherapy 14:115–124
YoungH.-K.,
SkurrayR. A.,
AmyesS. G. B.1987; Plasmid-mediated trimethoprim-resistance in Staphylococcus aureus: characterization of the first gram-positive plasmid dihydrofolate reductase (type SI). Biochemical Journal 243:309–312
YoungH.-K.,
AmyesS. G. B.1986; A new mechanism of plasmid trimethoprim resistance: characterization of an inducible dihydrofolate reductase. Journal of Biological Chemistry 261:2503–2505
Trimethoprim resistance determinants encoding a dihydrofolate reductase in clinical isolates of Staphylococcus aureus and coagulase-negative staphylococci