TY - JOUR
T1 - Effect of antimicrobial treatment on the dynamics of ceftiofur resistance in enterobacteriaceae from adult California dairy cows
AU - Sheedy, David B.
AU - Okello, Emmanuel
AU - Williams, Deniece R.
AU - Precht, Katie
AU - Cella, Elisa
AU - Lehenbauer, Terry W.
AU - Aly, Sharif S.
N1 - Funding Information:
This research was funded by the California Department of Food and Agriculture (PI: S. Aly) and the University of California Davis?s School of Veterinary Medicine and Office of Research?s Principal Investigator Bridge Program (PI: S. Aly). The authors are grateful for the study dairies owners, personnel and staff. The authors acknowledge the technical support of Jake Koontz and Jennifer Crook.
Funding Information:
Data Availability Statement: This study was sponsored by the California Department of Food and
Funding Information:
Funding: This research was funded by the California Department of Food and Agriculture (PI: S. Aly) and the University of California Davis’s School of Veterinary Medicine and Office of Research’s Principal Investigator Bridge Program (PI: S. Aly).
Publisher Copyright:
© 2021 by the authors. Licensee MDPI, Basel, Switzerland.
PY - 2021/4
Y1 - 2021/4
N2 - Dairy farm use of antimicrobial drugs (AMD) is a risk for the selection of antimicrobial resistance (AMR); however, these resistance dynamics are not fully understood. A cohort study on two dairy farms enrolled 96 cows with their fecal samples collected three times weekly, for the first 60 days in milk. Enterobacteriaceae were enumerated by spiral plating samples onto MacConkey agar impregnated with 0, 1, 8, 16 and 30 µg/mL ceftiofur. Negative binomial regression analyzed AMR over time. The continuum of ceftiofur concentrations permitted estimation of the minimum inhibitory concentration (MIC) and analysis using interval regression. The most common systemic AMD was ceftiofur, administered in 94% of treatments (15/16 cows). Enterobacteriaceae did not grow in 88% of samples collected from non-AMD treated cows at 8 µg/mL ceftiofur. Samples from AMD treated cows had peak counts of resistant Enterobacteriaceae during AMD treatment and returned to baseline counts by 3–4 days post-treatment at 8 µg/mL. Sensitive Enterobacteriaceae (0–1 µg/mL ceftiofur) were reduced below pre-treated levels for 29–35 days post-AMD treatment. Population MIC peaked during AMD treatment and returned to baseline levels by 7–8 days. We conclude that the effect of systemic ceftiofur on the resistance of Enterobacteriaceae in early lactation dairy cows was limited in duration.
AB - Dairy farm use of antimicrobial drugs (AMD) is a risk for the selection of antimicrobial resistance (AMR); however, these resistance dynamics are not fully understood. A cohort study on two dairy farms enrolled 96 cows with their fecal samples collected three times weekly, for the first 60 days in milk. Enterobacteriaceae were enumerated by spiral plating samples onto MacConkey agar impregnated with 0, 1, 8, 16 and 30 µg/mL ceftiofur. Negative binomial regression analyzed AMR over time. The continuum of ceftiofur concentrations permitted estimation of the minimum inhibitory concentration (MIC) and analysis using interval regression. The most common systemic AMD was ceftiofur, administered in 94% of treatments (15/16 cows). Enterobacteriaceae did not grow in 88% of samples collected from non-AMD treated cows at 8 µg/mL ceftiofur. Samples from AMD treated cows had peak counts of resistant Enterobacteriaceae during AMD treatment and returned to baseline counts by 3–4 days post-treatment at 8 µg/mL. Sensitive Enterobacteriaceae (0–1 µg/mL ceftiofur) were reduced below pre-treated levels for 29–35 days post-AMD treatment. Population MIC peaked during AMD treatment and returned to baseline levels by 7–8 days. We conclude that the effect of systemic ceftiofur on the resistance of Enterobacteriaceae in early lactation dairy cows was limited in duration.
KW - Antimicrobial resistance
KW - Ceftiofur
KW - Dairy
KW - Medically important antimicrobial drugs
KW - Minimum inhibitory concentration
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U2 - 10.3390/microorganisms9040828
DO - 10.3390/microorganisms9040828
M3 - Article
AN - SCOPUS:85104019937
VL - 9
JO - Microorganisms
JF - Microorganisms
SN - 2076-2607
IS - 4
M1 - 828
ER -