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Age and diet effects on fecal populations and antibiotic resistance of a multi-drug resistant Escherichia coli in dairy calves

Permanent URL:
http://handle.nal.usda.gov/10113/57362
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Abstract:
Dairy calves are colonized at a very young age by a multi-drug resistant Escherichia coli (MDR EC) and research studies indicate that the prevalence is not related to recent use of antimicrobials, but that diet and other environmental factors are likely involved. To further investigate the occurrence of this bacterium, we sampled dairy calves on southwestern United States farms at one week of age through 6 months, and determined not only prevalence, but fecal concentrations of the MDR EC. The influence of feeding pasteurized (PWM) versus non-pasteurized (NPWM) waste milk was examined, and the effect of weaning was investigated. The number of fecal samples positive for MDR EC as well as their populations decreased (P < 0.01) with increasing calf age. Slight differences were observed when comparing PWM and NPWM feeding, with MDR EC concentration and prevalence in the latter group generally decreasing at younger ages. No significant differences were observed in the fecal concentrations of MDR EC due to weaning. No clear differences were observed in resistance when comparing calves fed PWM or NPWM. Approximately 41% of the MDR EC isolates collected throughout the study were resistant to 10 or more antibiotics, with two primary phenotypes: ACSSuT and MDR-AmpC. Based on the results herein, it appears that neither pasteurization of the waste milk or weaning, has a significant effect on the prevalence or concentration of MDR EC, and based on the age-associated decline in prevalence, they survive in an immature digestive system with limited bacterial diversity and competition for resources.
Author(s):
T. S. Edrington , R. L. Farrow , B. H. Carter , A. Islas , G. R. Hagevoort , T. R. Callaway , D. J. Nisbet
Subject(s):
Escherichia coli , animal age , antibiotic resistance , antibiotics , bacteria , bacterial colonization , calf feeding , dairy calves , diet , digestive system , environmental factors , farms , feces , milk , multiple drug resistance , pasteurization , pasteurized milk , phenotype , population dynamics , weaning , Southwestern United States
Source:
Agriculture 2012 12 1 v.2 no.3
Language:
English
Year:
2012
Collection:
Journal Articles, USDA Authors, Peer-Reviewed
Rights:
Works produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted.