1.Richmond, M. Antibiotic resistance and the evolution of bacteria. Nature 1983; 302: 657.
2.Huovinen, P, Pulkkinen, L, Helin, HL, Makila, M, Toivanen, P. Emergence of trimethoprim resistance in relation to drug consumption in a Finnish hospital from 1971 through 1984. Antimicrob Agents Chemother 1986; 29: 73–6.
3.Amyes, SGB, Smith, JT. R-factor trimethoprim resistance mechanism: An insusceptible target site. Biochem Biophys Res Commun 1974; 58: 412–8.
4.Amyes, SGB, Towner, KJ. Trimethoprim resistance; epidemiology and molecular aspects. J Med Microbiol 1990; 31: 1–19.
5.Jansson, C, Sköld, O. Appearance of a new trimethoprim resistance gene, dhfrIX, in Escherichia coli from Swine. Antimicrob Agents Chemother 1991; 35: 1891–9.
6.Steen, R, Sköld, O. Plasmid-borne or chromosomally mediated resistance by Tn7 is the most common response to ubiquitous use of trimethoprim. Antimicrob Agents Chemother 1985; 27: 933–7.
7.Pulkkinen, L, Huovinen, P, Vuorio, E, Toivanen, P. Characterization of trimethoprim resistance by use of probes specific for transposon Tn7. Antimicrob Agents Chemother 1984; 26: 82–6.
8.Mayer, KH, Fling, ME, Hopkins, JD, O'Brien, TF. Trimethoprim resistance in multiple genera of Enterobacteriaceae at a U.S. hospital: spread of the type II dihydrofolate reductase gene by a single plasmid. J Infect Dis 1985; 151: 783–9.
9.Fling, ME, Kopf, J, Richards, C. Characterization of plasmid pAZ1 and the type III dihydrofolate reductase gene. Plasmid 1988; 19: 30–3.
10.Sundström, L, Vinayagamoorthy, T, Sköld, O. Novel type of plasmid-borne resistance to trimethoprim. Antimicrob Agents Chemother 1987; 31: 60–6.
11.Chang, LL, Chang, SF, Chow, TY. R factor in urinary tract infection. J Formosan Med Assoc 1984; 83: 268–77.
12.Datta, N, Richards, H. Trimethoprim-resistant bacteria in hospital and in the community: spread of plasmids and transposons. In: Levy, SB, Clowes, RC, Koenig, RL, eds. Molecular biology: pathogenicity and ecology of bacterial plasmids. New York: 1981: 21–30.
13.Chang, SF, Chang, LL, Chow, TY, Wu, WJ, Chang, JC. Prevalence of transposons encoding kanamycin, ampicillin and trimethoprim resistance in isolates from urinary tract infections detected by using DNA probes. Kaohsiung J Med Sci 1992; 8: 141–7.
14.Lin, SR, Chang, SF. Drug resistance and plasmid profile of shigellae in Taiwan. Epidemiol Infect 1991; 108: 87–97.
15.Kado, CI, Liu, ST. Rapid procedure for detection and isolation of large and small plasmids. J Bacteriol 1981; 145: 1365–73.
16.Maniatis, T, Fritsch, EF, Sambrook, J. Molecular cloning, 2nd edn. Cold Spring Harbor, NY: Cold Spring Harbor Laboratory, 1989.
17.Gosti-Testu, F, Norris, V, Brevet, J. Restriction map of Tn7. Plasmid 1983; 10: 96–9.
18.Birnboim, HC, Doly, J.A. A rapid alkaline extraction procedure for screening recombinant plasmid DNA. Nucleic Acids Res 1979; 7: 1513–23.
19.Goldstein, FW, Papadopoulou, B, Acar, JF. The changing pattern of trimethoprim resistance in Paris, with a review of worldwide experience. Rev Infect Dis 1986; 8: 725–37.
20.Romero, E, Perduca, M. Compatibility groups of R-factors for trimethoprim resistance isolated in Italy. J Antimicrob Chemother 1977; 3: 35–8.
21.Huovinen, P, Pulkkinen, L, Toivanen, P. Transferable trimethoprim resistance in three Finnish hospitals. J Antimicrob Chemother 1983; 12: 249–56.
22.Brumfitt, W, Hamilton-Miller, JMT, Wood, A. Evidence for a slowing in trimethoprim resistance during 1981 – a comparison with earlier years. J Antimicrob Chemother 1983; 11: 503–9.
23.Murray, BE, Alvarado, T, Kim, KH, et al. Increasing resistance to trimethoprim-sulfamethoxazole among isolates of Escherichia coli in developing countries. J Infect Dis 1985; 152: 1107–13.
24.Fleming, MP, Datta, N, Grüneberg, RN. Trimethoprim resistance determined by R factors. Br Med J 1972; 1: 726–8.
25.Jobanputra, RS, Datta, N. Trimethoprim R factors in enterobacteria from clinical specimens. J Med Microbiol 1974; 7: 169–77.
26.Bannatyne, RM, Toma, S, Cheung, R, Hu, G. Resistance to trimethoprim and other antibiotics in Ontario Shigellae. Lancet 1980; i: 425–6.
27.Threlfall, EJ, Rowe, B, Huq, I. Plasmid-encoded multiple antibiotic resistance in Vibrio Cholerae E1 Tor from Bangladesh. Lancet 1980; i: 1247–8.
28.Kraft, CA, Timbury, MC, Platt, DJ. Distribution and genetic location of Tn7 in trimethoprim-resistant Escherichia coli. J Med Microbiol 1986; 22: 125–31.
29.Heikkila, E, Sundström, L, Skurnik, M, Huovinen, P. Analysis of genetic localization of the type I trimethoprim resistance gene from Escherichia coli isolated in Finland. Antimicrob Agents Chemother 1991; 35: 1562–9.
30.Radstrom, P, Swedberg, G, Sköld, O. Genetic analyses of sulfonamide resistance and its dissemination in gram-negative bacteria illustrate new aspects of R plasmid evolution. Antimicrob Agents Chemother 1991; 35: 1840–8.
31.Sundström, L, Radstrom, P, Swedberg, G, Sköld, O. Site specific recombination promotes linkage between trimethoprim and sulfonamide resistance genes. Sequence characterization of dhfrV and sull and a recombination active locus of Tn21. MGG 1988; 213: 191–201.
32.Sundström, L, Sköld, O. The dhfrI trimethoprim resistance gene of Tn7 can be found at specific sites in other genetic surroundings. Antimicrob Agents Chemother 1990; 34: 642–50.