Journal article
Role of Calf-Adapted Escherichia coli in Maintenance of Antimicrobial Drug Resistance in Dairy Calves
Applied and environmental microbiology, Vol.70(2), pp.752-757
02/2004
Handle:
https://hdl.handle.net/2376/114172
PMCID: PMC348837
PMID: 14766551
Abstract
The prevalence of antimicrobial drug-resistant bacteria is typically highest in younger animals, and prevalence is not necessarily related to recent use of antimicrobial drugs. In dairy cattle, we hypothesize that antimicrobial drug-resistant, neonate-adapted bacteria are responsible for the observed high frequencies of resistant
Escherichia coli
in calves. To explore this issue, we examined the age distribution of antimicrobial drug-resistant
E. coli
from Holstein cattle at a local dairy and conducted an experiment to determine if low doses of oxytetracycline affected the prevalence of antimicrobial drug-resistant
E. coli
. Isolates resistant to tetracycline (>4 μg/ml) were more prevalent in <3-month-old calves (79%) compared with lactating cows (14%). In an experimental trial where calves received diets supplemented with or without oxytetracycline, the prevalence of tetracycline-resistant
E. coli
was slightly higher for the latter group (
P
= 0.039), indicating that drug use was not required to maintain a high prevalence of resistant
E. coli
. The most common resistance pattern among calf
E. coli
isolates included resistance to streptomycin (>12 μg/ml), sulfadiazine (>512 μg/ml), and tetracycline (>4 μg/ml) (SSuT), and this resistance pattern was most prevalent during the period when calves were on milk diets. To determine if prevalence was a function of differential fitness, we orally inoculated animals with nalidixic acid-resistant strains of SSuT
E. coli
and susceptible
E. coli
. Shedding of SSuT
E. coli
was significantly greater than that of susceptible strains in neonatal calves (
P
< 0.001), whereas there was no difference in older animals (
P
= 0.5). These data support the hypothesis that active selection for traits linked to the SSuT phenotype are responsible for maintaining drug-resistant
E. coli
in this population of dairy calves.
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Details
- Title
- Role of Calf-Adapted Escherichia coli in Maintenance of Antimicrobial Drug Resistance in Dairy Calves
- Creators
- Artashes R Khachatryan - Department of Veterinary Microbiology and PathologyDale D Hancock - Department of Veterinary Microbiology and PathologyThomas E Besser - Department of Veterinary Microbiology and PathologyDouglas R Call - Department of Veterinary Microbiology and Pathology
- Publication Details
- Applied and environmental microbiology, Vol.70(2), pp.752-757
- Academic Unit
- Veterinary Clinical Sciences, Department of; Veterinary Microbiology and Pathology, Department of; Paul G. Allen School for Global Animal Health
- Publisher
- American Society for Microbiology
- Identifiers
- 99900547571801842
- Language
- English
- Resource Type
- Journal article