This article is a commentary on:
Genetic mechanisms of antimicrobial resistance identified in Salmonella enterica, Escherichia coli, and Enteroccocus spp. isolated from U.S. food animals
by Frye, J. G., and Jackson, C. R. (2013). Front. Microbiol. 4:135. doi: 10.3389/fmicb.2013.00135
While Frye and Jackson do a good job describing the common mechanisms of resistance found in food animals in the U.S., they err in stating that in the U.S. extended spectrum β-lactamases (ESBLs) “thus far have only been found in human and not food animal isolates.”
In fact, Wittum et al., in 2010 first reported the collection of Escherichia coli expressing CTX-M-type ESBLs in fecal isolates from healthy cattle at a livestock market and from a diagnostic isolate submitted to the Ohio Animal Disease Diagnostic Laboratory. Since then, CTX-M-type ESBLs have been found in E. coli collected from healthy dairy calves in the western U.S. (Davis et al., 2011) and from 5 of 20 dairy farms in Ohio (Mollenkopf et al., 2012); in clinical Salmonella enterica isolates from swine in Minnesota and from turkeys in 4 states (Wittum et al., 2012); in E. coli from swine finishing barns in Michigan and Ohio and in Klebsiella pneumoniae from swine in Illinois (Mollenkopf et al., 2013).
We are not aware of studies finding CTX-M-type ESBLs in isolates from broiler chickens, but a retail chicken meat E. coli isolate expressing CTX-M-type ESBLs from Pennsylvania has been reported (Doi et al., 2010). Given the situation in other livestock species and in other countries, we expect the lack of detection of CTX-M-type ESBLs in U.S. chicken isolates is more the result of lack of appropriate studies than a real absence of these on chicken farms. In addition to CTX-M-type ESBLs, the study of dairy calves in the western U.S. also found E. coli expressing OXA-type ESBLs (Davis et al., 2011).
References
Davis, M. A., Besser, T. E., Orfe, L. H., Baker, K. N., Lanier, A. S., Broschat, S. L., et al. (2011). Genotypic-phenotypic discrepancies between antibiotic resistance characteristics of Escherichia coli isolates from calves in management settings with high and low antibiotic use. Appl. Environ. Microbiol. 77, 3293–3299. doi: 10.1128/AEM.02588-10
Doi, Y., Paterson, D. L., Egea, P., Pascual, A., López-Cerero, L., Navarro, M. D., et al. (2010). Extended-spectrum and CMY-type beta-lactamase-producing Escherichia coli in clinical samples and retail meat from Pittsburgh, USA and Seville, Spain. Clin. Microbiol. Infect. 16, 33–38. doi: 10.1111/j.1469-0691.2009.03001.x
Mollenkopf, D. F., Mirecki, J. M., Daniels, J. B., Funk, J. A., Henry, S. C., Hansen, G. E., et al. (2013). Escherichia coli and Klebsiella pneumoniae producing CTX-M cephalosporinase from swine finishing barns and their association with antimicrobial use. Appl. Environ. Microbiol. 79, 1052–1054. doi: 10.1128/AEM.03169-12
Mollenkopf, D. F., Weeman, M. F., Daniels, J. B., Abley, M. J., Mathews, J. L., Gebreyes, W. A., et al. (2012). Variable within- and between-herd diversity of CTX-M cephalosporinase-bearing Escherichia coli isolates from dairy cattle. Appl. Environ. Microbiol. 78, 4552–4560. doi: 10.1128/AEM.00373-12
Wittum, T. E., Mollenkopf, D. F., and Erdman, M. M. (2012). Detection of Salmonella enterica isolates producing CTX-M Cephalosporinase in U.S. livestock populations. Appl. Environ. Microbiol. 78, 7487–7491. doi: 10.1128/AEM.01682-12
Citation: Roach S and Wallinga D (2013) Commentary on genetic mechanisms of antimicrobial resistance in bacteria from U.S. food animals: ESBLs are here. Front. Microbiol. 4:214. doi: 10.3389/fmicb.2013.00214
Received: 28 June 2013; Accepted: 09 July 2013;
Published online: 30 July 2013.
Edited by:
Henk Aarts, National Institute for Public Health and the Environment, NetherlandsReviewed by:
Axel Cloeckaert, Institut National de la Recherche Agronomique, FranceCopyright © 2013 Roach and Wallinga. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
*Correspondence: sroach@foodanimalconcerns.org