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Rights Statements InC/1.0 , Open Access
Journal article
Genotypic-phenotypic discrepancies between antibiotic resistance characteristics of Escherichia coli from calves in high and low antibiotic use management settings
Applied and environmental microbiology, Vol.77(10), pp.3293-3299
05/2011
Handle:
https://hdl.handle.net/2376/5996
PMID: 21421795
Abstract
We hypothesized that bacterial populations growing in the absence of antibiotics will accumulate more resistance gene mutations than bacterial populations growing in the presence of antibiotics. If this is so, the prevalence of dysfunctional resistance genes (resistance pseudogenes) could provide a measure of the level of antibiotic exposure present in a given environment. As a proof-of-concept test, we assayed field strains of Escherichia coli for their resistance genotypes using a resistance gene microarray and further characterized isolates that had resistance phenotype-genotype discrepancies. We found a small but significant association between the prevalence of isolates with resistance pseudogenes and the lower antibiotic use environment of a beef cow-calf operation versus a higher antibiotic use dairy calf ranch (Fisher's exact test, P = 0.044). Other significant findings include a very strong association between the dairy calf ranch isolates and phenotypes unexplained by well-known resistance genes (Fisher's exact test, P < 0.0001). Two novel resistance genes were discovered in E. coli isolates from the dairy calf ranch, one associated with resistance to aminoglycosides and one associated with resistance to trimethoprim. In addition, isolates resistant to expanded-spectrum cephalosporins but negative for blaCMY-2 had mutations in the promoter regions of the chromosomal E. coli ampC gene consistent with reported overexpression of native AmpC beta-lactamase. Similar mutations in hospital E. coli isolates have been reported worldwide. Prevalence or rates of E. coli ampC promoter mutations may be used as a marker for high expanded-spectrum cephalosporin use environments.
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Details
- Title
- Genotypic-phenotypic discrepancies between antibiotic resistance characteristics of Escherichia coli from calves in high and low antibiotic use management settings
- Creators
- Margaret A. Davis (Author)Thomas E. Besser (Author)Lisa H. Orfe (Author)Katherine N. K. Baker (Author)Amelia S. Lanier (Author)Shira L. Broschat (Author)Daniel New (Author)Douglas R Call (Author)
- Publication Details
- Applied and environmental microbiology, Vol.77(10), pp.3293-3299
- Academic Unit
- School of Electrical Engineering and Computer Science; Paul G. Allen School for Global Animal Health
- Grant note
- N01-A1-30055 / PHS HHS
- Identifiers
- 99900502806701842
- Copyright
- In copyright ; openAccess ; http://rightsstatements.org/vocab/InC/1.0/ ; http://purl.org/eprint/accessRights/OpenAccess
- Language
- English
- Resource Type
- Journal article