RESEARCH 12. Centers for Disease Control and Prevention/Food and Drug Administration; U.S. Department of Agriculture. National Antibiotic Resistance Monitoring System. Atlanta: The Centers; 1999. 13. Levesque C, Piche L, Larose C, Roy PH. PCR mapping of integrons reveals several novel combinations of resistance genes. Antimicrob Agents Chemother 1995;39:185–91. 14. White PA, McIver CJ, Rawlinson WD. Integrons and gene cassettes in the enterobacteriaceae. Antimicrob Agents Chemother 2001;45:2658–61. 15. Mazel D, Dychinco B, Webb VA, Davies J. Antibiotic resistance in the ECOR collection: integrons and identification of a novel aad gene. Antimicrob Agents Chemother 2000;44:1568–74. 16. Huang X, Madan A. CAP3: a DNA sequence assembly program. Genome Res 1999;9:868–77. 17. Altschul SF, Gish W, Miller W, Myers EW, Lipman DJ. Basic local alignment search tool. J Mol Biol 1990;215:403–10. 18. Thompson JD, Higgins DG, Gibson TJ. CLUSTAL W: improving the sensitivity of progressive multiple sequence alignment through sequence weighting, position-specific gap penalties and weight matrix choice. Nucleic Acids Res 1994;22:4673–80. 19. Ash RJ. Antibiotic resistance of gram-negative bacteria in rivers, United States. Emerg Infect Dis 2002;8:713–6. 20. Goni-Urriza M, Capdepuy M, Arpin C, Raymond N, Caumette P, Quentin C, et al. Impact of an urban effluent on antibiotic resistance of riverine Enterobacteriaceae and Aeromonas spp. Appl Environ Microbiol 2000;66:125–32. 21. American Academy of Microbiology. Antimicrobial resistance: an ecological perspective. Washington: American Society for Microbiology; 1999. p. 1–14. 22. Wegener HC, Aarestrup FM, Jensen LB, Hammerum AM, Bager F. Use of antimicrobial growth promoters in food animals and Enterococcus faecium resistance to therapeutic antimicrobial drugs in Europe. Emerg Infect Dis 1999;5:329–35. 23. Hall RM, Collis CM. Antibiotic resistance in gram-negative bacteria: the role of gene cassettes and integrons. Drug Resist Updat 1998;1:109–19. 24. Bass L, Liebert CA, Lee MD, Summers AO, White DG, Thayer SG, et al. Incidence and characterization of integrons, genetic elements mediating multiple-drug resistance, in avian Escherichia coli. Antimicrob Agents Chemother 1999;43:2925–9. OPPORTUNITIES FOR PEER REVIEWERS The editors of Emerging Infectious Diseases seek to increase the roster of reviewers for manuscripts submitted by authors all over the world for publication in the journal. If you are interested in reviewing articles on emerging infectious disease topics, please e-mail your name, address, curriculum vitae, and areas of expert- ise to eideditor@cdc.gov At Emerging Infectious Diseases, we always request reviewers’ consent before sending manuscripts, limit review requests to three or four per year, and allow 2-4 weeks for completion of reviews. We consider reviewers invaluable in the process of selecting and publishing high-quality scientific articles and acknowledge their contributions in the journal once a year. Even though it brings no financial compensation, participation in the peer-review process is not without rewards. Manuscript review provides scientists at all stages of their career opportunities for professional growth by familiarizing them with research trends and the latest work in the field of infectious diseases and by improving their own skills for presenting scientific information through constructive criticism of those of their peers. To view the spectrum of articles we publish, information for authors, and our extensive style guide, visit the journal web site at www.cdc.gov/eid. For more information on participating in the peer-review process of Emerging Infectious Diseases, e-mail eideditor@cdc.gov or call the journal office at 404-371-5329. 25. Cech I, Essman A. Water sanitation practices on the Texas-Mexico border: implications for physicians on both sides. South Med J 1992;85:1053–64. 26. McEwen SA, Fedorka-Cray PJ. Antimicrobial use and resistance in animals. Clin Infect Dis 2002;34(Suppl 3):S93–106. 27. Schwarz S, Chaslus-Dancla E. Use of antimicrobials in veterinary medicine and mechanisms of resistance. Vet Res 2001;32:201–25. 28. Texas Water Development Board, New Mexico Water Resources Research Institute. Transboundary aquifers of the El Paso/Ciudad Juarez/Las Cruces region. El Paso (TX): The Institute; 1997. p. 152. 29. Simpson JM, Santo Domingo JW, Reasoner DJ. Microbial source tracking: state of the science. Environ Sci Technol 2002;36:5279–88. 30. Rosser SJ, Young HK. Identification and characterization of class 1 integrons in bacteria from an aquatic environment. J Antimicrob Chemother 1999;44:11–8. 31. Sundstrom L, Radstrom P, Swedberg G, Skold O. Site-specific recom- bination promotes linkage between trimethoprim- and sulfonamide- resistance genes. Sequence characterization of dhfrV and sulI and a recombination active locus of Tn21. Mol Gen Genet 1988;213:191–201. 32. Pillai SD, Pepper IL. Transposon Tn5 as an identifiable marker in Rhizobia: survival and genetic stability of Tn5 mutant bean Rhizobia under temperature stressed conditions in desert soils. Microb Ecol 1990;21:21–33. 33. Sundstrom L, Roy PH, Skold O. Site-specific insertion of three struc- tural gene cassettes in transposon Tn7. J Bacteriol 1991;173:3025–8. 34. Hansson K, Sundstrom L, Pelletier A, Roy PH. IntI2 integron inte- grase in Tn7. J Bacteriol 2002;184:1712–21. 35. Huovinen P, Sundstrom L, Swedberg G, Skold O. Trimethoprim and sulfonamide resistance. Antimicrob Agents Chemother 1995;39:279–89. Address for correspondence: Suresh D. Pillai, Department of Poultry Science, 418D Kleberg Center, MS 2472 TAMUS, Texas A&M University, College Station, Texas 77843-2472, USA; fax: 979-845-1921; email: spillai@poultry.tamu.edu 826 Emerging Infectious Diseases • Vol. 9, No. 7, July 2003