AEM
Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Houndt, T.
Right arrow Articles by Ochman, H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Houndt, T.
Right arrow Articles by Ochman, H.
Agricola
Right arrow Articles by Houndt, T.
Right arrow Articles by Ochman, H.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, December 2000, p. 5406-5409, Vol. 66, No. 12
0099-2240/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.

Long-Term Shifts in Patterns of Antibiotic Resistance in Enteric Bacteria

Tara Houndt and Howard Ochman*

Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, Arizona 85721

Received 10 August 2000/Accepted 20 September 2000

Several mechanisms are responsible for the ability of microorganisms to tolerate antibiotics, and the incidence of resistance to these compounds within bacterial species has increased since the commercial use of antibiotics became widespread. To establish the extent of and changes in the diversity of antibiotic resistance patterns in natural populations, we determined the MICs of five antibiotics for collections of enteric bacteria isolated from diverse hosts and geographic locations and during periods before and after commercial application of antibiotics began. All of the pre-antibiotic era strains were susceptible to high levels of these antibiotics, whereas 20% of strains from contemporary populations of Escherichia coli and Salmonella enterica displayed high-level resistance to at least one of the antibiotics. In addition to the increase in the frequency of high-level resistance, background levels, conferred by genes providing nonspecific low-level resistance to multiple antibiotics, were significantly higher among contemporary strains. Changes in the incidence and levels of antibiotic resistance are not confined to particular segments of the bacterial population and reflect responses to the increased exposure of bacteria to antimicrobial compounds over the past several decades.

* Corresponding author. Mailing address: Department of Ecology and Evolutionary Biology, 233 Life Sciences South, University of Arizona, Tucson, AZ 85721. Phone: (520) 626-8355. Fax: (520) 621-3709. E-mail: hochman{at}emailarizona.edu.

Applied and Environmental Microbiology, December 2000, p. 5406-5409, Vol. 66, No. 12
0099-2240/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.


This article has been cited by other articles:



Home Help [Feedback] [For Subscribers] [Archive] [Search] [Contents]
J. Bacteriol. Microbiol. Mol. Biol. Rev. Eukaryot. Cell All ASM Journals

Copyright © 2000 by the American Society for Microbiology. All rights reserved.