TY - JOUR

T1 - The effect of colistin treatment on the selection of colistin-resistant Escherichia coli in weaner pigs

AU - Ahmed, Shahana

AU - Hansen, Claus

AU - Dahlkilde, Ane Laursen

AU - Herrero-Fresno, Ana

AU - Pedersen, Ken Steen

AU - Nielsen, Jens Peter

AU - Olsen, John Elmerdahl

N1 - Funding Information: Funding: This study was funded by the Agriculture and Food Council, SEGES, Denmark (LD-32709-14-0017). Publisher Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland.

PY - 2021

Y1 - 2021

N2 - The treatment of diarrhea in the postweaning period is a common reason for the use of antimicrobials in pig production, and Escherichia coli is the single most important causative agent for this condition. Colistin has recently been classified as a critically important antimicrobial for human health, as it is a last-resort drug against certain multi-drug-resistant Gram-negative bacteria. Therefore, the use of colistin has been significantly reduced in some countries, including Denmark. Despite this, the drug is still commonly used to treat diarrhea in pigs in many countries, and there is a need to understand the risks associated with this practice. We performed a prospective cohort study to investigate the effect of colistin treatment on the changes in the average minimum inhibitory concentration (MIC) in commensal E. coli in a pig herd where no colistin-resistant bacteria were detectable before treatment. One group of pigs was batch treated with colistin after the clinical observation of diarrhea, one group was batch treated with colistin approximately 10 days before the expected onset of diarrhea, and a control group was not treated with colistin but provided with nonantimicrobial antidiarrheal feed supplement. Treatment with colistin in the dose and time combinations used did not result in a significant increase in the average colistin MIC values in E. coli. Moreover, no E. coli strains showed a MIC above the breakpoint of >2 mg/L against colistin. Co-selection of resistance to other antimicrobials was not observed.

AB - The treatment of diarrhea in the postweaning period is a common reason for the use of antimicrobials in pig production, and Escherichia coli is the single most important causative agent for this condition. Colistin has recently been classified as a critically important antimicrobial for human health, as it is a last-resort drug against certain multi-drug-resistant Gram-negative bacteria. Therefore, the use of colistin has been significantly reduced in some countries, including Denmark. Despite this, the drug is still commonly used to treat diarrhea in pigs in many countries, and there is a need to understand the risks associated with this practice. We performed a prospective cohort study to investigate the effect of colistin treatment on the changes in the average minimum inhibitory concentration (MIC) in commensal E. coli in a pig herd where no colistin-resistant bacteria were detectable before treatment. One group of pigs was batch treated with colistin after the clinical observation of diarrhea, one group was batch treated with colistin approximately 10 days before the expected onset of diarrhea, and a control group was not treated with colistin but provided with nonantimicrobial antidiarrheal feed supplement. Treatment with colistin in the dose and time combinations used did not result in a significant increase in the average colistin MIC values in E. coli. Moreover, no E. coli strains showed a MIC above the breakpoint of >2 mg/L against colistin. Co-selection of resistance to other antimicrobials was not observed.

KW - Antimicrobial resistance

KW - Colistin

KW - Commensal

KW - E. coli

KW - Pig diarrhea

U2 - 10.3390/antibiotics10040465

DO - 10.3390/antibiotics10040465

M3 - Journal article

C2 - 33923889

AN - SCOPUS:85105315972

VL - 10

JO - Antibiotics

JF - Antibiotics

SN - 2079-6382

IS - 4

M1 - 465

ER -