title: The distribution of the DHFR genes in trimethoprim-resistant urinary tract isolates from Taiwan.
abstract: Between July 1987 and June 1989, 1054 urinary isolates of enterobacteria from Kaohsiung, Taiwan were studied for their trimethoprim resistance. Trimethoprim resistance was defined as MIC greater than 4 micrograms/ml and high-level resistance by MIC greater than 1000 micrograms/ml. The incidence of trimethoprim resistance increased from 33.6% in 1987 to 42.1% in 1989. Among the resistant strains studied, 90% were resistant to high levels of trimethoprim. An increase in the proportion of resistant strains (33.9-46.3%) exhibiting high-level non-transferable trimethoprim resistance was noted. The distribution of the dihydrofolate reductase (DHFR) genes by colony hybridization in 374 trimethoprim-resistant isolates revealed the presence of type I and type V DHFR genes in most of these isolates (45.4% and 10.4% respectively). Type I was predominant in Escherichia coli whereas type V was frequently seen in Enterobacter spp. None showed homology with the type II and type III DHFR probe DNA. In addition, transposon Tn7 was present in 7.8% of 374 trimethoprim-resistant enterobacteria.
authors.affiliation: Department of Microbiology, Kaohsiung Medical College, Taiwan, Republic of China.
authors.forename: L L
authors.initials: LL
authors.lastname: Chang
authors.forename: S F
authors.initials: SF
authors.lastname: Chang
authors.forename: T Y
authors.initials: TY
authors.lastname: Chow
authors.forename: W J
authors.initials: WJ
authors.lastname: Wu
authors.forename: J C
authors.initials: JC
authors.lastname: Chang
mesh_terms: D004251:DNA Transposable Elements / Q000235:genetics; D004754:Enterobacter / Q000235:genetics; D004755:Enterobacteriaceae / Q000235:genetics*; D004756:Enterobacteriaceae Infections / Q000382:microbiology*; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D007709:Klebsiella / Q000235:genetics; D015995:Prevalence; D013624:Taiwan; D013762:Tetrahydrofolate Dehydrogenase / Q000235:genetics*; D014296:Trimethoprim Resistance / Q000235:genetics*; D014552:Urinary Tract Infections / Q000382:microbiology*
chemical_list: D004251:DNA Transposable Elements; D013762:Tetrahydrofolate Dehydrogenase