Detection of novel trimethoprim resistance determinants in the United Kingdom using biotin-labelled DNA probes.
Two collections of trimethoprim R plasmids, isolated from strains of Escherichia coli during 1978-83 and 1987-8 respectively, were retrospectively screened with specific biotinylated DNA probes for the presence of genes encoding particular DHFR enzymes. The results confirmed that the type I DHFR gene was the predominant plasmid-encoded gene conferring trimethoprim resistance in strains of E. coli from the Nottingham area of the UK, but indicated that genes encoding the more recently recognized types of DHFR enzymes had appeared in the bacterial gene pool and could be recognized with increased frequency in the latter plasmid collection. This was particularly true of the type IIIa and type VII enzymes which together accounted for 27% of the trimethoprim R plasmids examined in 1987-8.
Towner
K J
KJ
Department of Microbiology, University Hospital, Nottingham, UK.
Carter
G I
GI
Young
H K
HK
Amyes
S G
SG
D000818:Animals; D015342:DNA Probes; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D006801:Humans; D009693:Nucleic Acid Hybridization; D011815:R Factors; D012189:Retrospective Studies; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics*; D014296:Trimethoprim Resistance / Q000235:genetics*; D006113:United Kingdom
D015342:DNA Probes; D013762:Tetrahydrofolate Dehydrogenase