Lower prevalence of antibiotic-resistant enterococci on U.S. conventional poultry farms that transitioned to organic practices

Amy R. Sapkota, R. Michael Hulet, Guangyu Zhang, Patrick McDermott, Erinna L. Kinney, Kellogg Schwab, Sam W. Joseph

Research output: Contribution to journalArticle

Abstract

Background: In U.S. conventional poultry production, antimicrobials are used for therapeutic, prophylactic, and nontherapeutic purposes. Researchers have shown that this can select for antibiotic-resistant commensal and pathogenic bacteria on poultry farms and in poultry-derived products. However, no U.S. studies have investigated on-farm changes in resistance as conventional poultry farms transition to organic practices and cease using antibiotics. Objective: We investigated the prevalence of antibiotic-resistant Enterococcus on U.S. conventional poultry farms that transitioned to organic practices. Methods: Poultry litter, feed, and water samples were collected from 10 conventional and 10 newly organic poultry houses in 2008 and tested for Enterococcus. Enterococcus (n = 259) was identified using the Vitek ® 2 Compact System and tested for susceptibility to 17 antimicrobials using the Sensititre™ microbroth dilution system. Data were analyzed using SAS software (version 9.2), and statistical associations were derived based on generalized linear mixed models. Results: Litter, feed, and water samples were Enterococcus positive. The percentages of resistant Enterococcus faecalis and resistant Enterococcus faecium were significantly lower (p <0.05) among isolates from newly organic versus conventional poultry houses for two (erythromycin and tylosin) and five (ciprofloxacin, gentamicin, nitrofurantoin, penicillin, and tetracycline) antimicrobials, respectively. Forty-two percent of E. faecalis isolates from conventional poultry houses were multidrug resistant (MDR; resistant to three or more antimicrobial classes), compared with 10% of isolates from newly organic poultry houses (p = 0.02); 84% of E. faecium isolates from conventional poultry houses were MDR, compared with 17% of isolates from newly organic poultry houses (p <0.001). Conclusions: Our findings suggest that the voluntary removal of antibiotics from large-scale U.S. poultry farms that transition to organic practices is associated with a lower prevalence of antibiotic-resistant and MDR Enterococcus.

Original languageEnglish (US)
Pages (from-to)1622-1628
Number of pages7
JournalEnvironmental Health Perspectives
Volume119
Issue number11
DOIs
StatePublished - Nov 2011

Fingerprint

Enterococcus
Poultry
Anti-Bacterial Agents
Enterococcus faecium
Enterococcus faecalis
Farms
Poultry Products
Tylosin
Nitrofurantoin
Water
Erythromycin
Ciprofloxacin
Gentamicins
Tetracycline
Penicillins
Linear Models
Software
Research Personnel
Bacteria

Keywords

  • Antibiotic resistance
  • Antibiotic-resistant bacteria
  • Antimicrobial growth promoter
  • Enterococcus
  • Organic poultry

ASJC Scopus subject areas

  • Health, Toxicology and Mutagenesis
  • Public Health, Environmental and Occupational Health

Cite this

Lower prevalence of antibiotic-resistant enterococci on U.S. conventional poultry farms that transitioned to organic practices. / Sapkota, Amy R.; Hulet, R. Michael; Zhang, Guangyu; McDermott, Patrick; Kinney, Erinna L.; Schwab, Kellogg; Joseph, Sam W.

In: Environmental Health Perspectives, Vol. 119, No. 11, 11.2011, p. 1622-1628.

Research output: Contribution to journalArticle

Sapkota, Amy R. ; Hulet, R. Michael ; Zhang, Guangyu ; McDermott, Patrick ; Kinney, Erinna L. ; Schwab, Kellogg ; Joseph, Sam W. / Lower prevalence of antibiotic-resistant enterococci on U.S. conventional poultry farms that transitioned to organic practices. In: Environmental Health Perspectives. 2011 ; Vol. 119, No. 11. pp. 1622-1628.
@article{3d62f1437cc74dd0a3fb8d72149ae866,
title = "Lower prevalence of antibiotic-resistant enterococci on U.S. conventional poultry farms that transitioned to organic practices",
abstract = "Background: In U.S. conventional poultry production, antimicrobials are used for therapeutic, prophylactic, and nontherapeutic purposes. Researchers have shown that this can select for antibiotic-resistant commensal and pathogenic bacteria on poultry farms and in poultry-derived products. However, no U.S. studies have investigated on-farm changes in resistance as conventional poultry farms transition to organic practices and cease using antibiotics. Objective: We investigated the prevalence of antibiotic-resistant Enterococcus on U.S. conventional poultry farms that transitioned to organic practices. Methods: Poultry litter, feed, and water samples were collected from 10 conventional and 10 newly organic poultry houses in 2008 and tested for Enterococcus. Enterococcus (n = 259) was identified using the Vitek {\circledR} 2 Compact System and tested for susceptibility to 17 antimicrobials using the Sensititre™ microbroth dilution system. Data were analyzed using SAS software (version 9.2), and statistical associations were derived based on generalized linear mixed models. Results: Litter, feed, and water samples were Enterococcus positive. The percentages of resistant Enterococcus faecalis and resistant Enterococcus faecium were significantly lower (p <0.05) among isolates from newly organic versus conventional poultry houses for two (erythromycin and tylosin) and five (ciprofloxacin, gentamicin, nitrofurantoin, penicillin, and tetracycline) antimicrobials, respectively. Forty-two percent of E. faecalis isolates from conventional poultry houses were multidrug resistant (MDR; resistant to three or more antimicrobial classes), compared with 10{\%} of isolates from newly organic poultry houses (p = 0.02); 84{\%} of E. faecium isolates from conventional poultry houses were MDR, compared with 17{\%} of isolates from newly organic poultry houses (p <0.001). Conclusions: Our findings suggest that the voluntary removal of antibiotics from large-scale U.S. poultry farms that transition to organic practices is associated with a lower prevalence of antibiotic-resistant and MDR Enterococcus.",
keywords = "Antibiotic resistance, Antibiotic-resistant bacteria, Antimicrobial growth promoter, Enterococcus, Organic poultry",
author = "Sapkota, {Amy R.} and Hulet, {R. Michael} and Guangyu Zhang and Patrick McDermott and Kinney, {Erinna L.} and Kellogg Schwab and Joseph, {Sam W.}",
year = "2011",
month = "11",
doi = "10.1289/ehp.1003350",
language = "English (US)",
volume = "119",
pages = "1622--1628",
journal = "Environmental Health Perspectives",
issn = "0091-6765",
publisher = "Public Health Services, US Dept of Health and Human Services",
number = "11",

}

TY - JOUR

T1 - Lower prevalence of antibiotic-resistant enterococci on U.S. conventional poultry farms that transitioned to organic practices

AU - Sapkota, Amy R.

AU - Hulet, R. Michael

AU - Zhang, Guangyu

AU - McDermott, Patrick

AU - Kinney, Erinna L.

AU - Schwab, Kellogg

AU - Joseph, Sam W.

PY - 2011/11

Y1 - 2011/11

N2 - Background: In U.S. conventional poultry production, antimicrobials are used for therapeutic, prophylactic, and nontherapeutic purposes. Researchers have shown that this can select for antibiotic-resistant commensal and pathogenic bacteria on poultry farms and in poultry-derived products. However, no U.S. studies have investigated on-farm changes in resistance as conventional poultry farms transition to organic practices and cease using antibiotics. Objective: We investigated the prevalence of antibiotic-resistant Enterococcus on U.S. conventional poultry farms that transitioned to organic practices. Methods: Poultry litter, feed, and water samples were collected from 10 conventional and 10 newly organic poultry houses in 2008 and tested for Enterococcus. Enterococcus (n = 259) was identified using the Vitek ® 2 Compact System and tested for susceptibility to 17 antimicrobials using the Sensititre™ microbroth dilution system. Data were analyzed using SAS software (version 9.2), and statistical associations were derived based on generalized linear mixed models. Results: Litter, feed, and water samples were Enterococcus positive. The percentages of resistant Enterococcus faecalis and resistant Enterococcus faecium were significantly lower (p <0.05) among isolates from newly organic versus conventional poultry houses for two (erythromycin and tylosin) and five (ciprofloxacin, gentamicin, nitrofurantoin, penicillin, and tetracycline) antimicrobials, respectively. Forty-two percent of E. faecalis isolates from conventional poultry houses were multidrug resistant (MDR; resistant to three or more antimicrobial classes), compared with 10% of isolates from newly organic poultry houses (p = 0.02); 84% of E. faecium isolates from conventional poultry houses were MDR, compared with 17% of isolates from newly organic poultry houses (p <0.001). Conclusions: Our findings suggest that the voluntary removal of antibiotics from large-scale U.S. poultry farms that transition to organic practices is associated with a lower prevalence of antibiotic-resistant and MDR Enterococcus.

AB - Background: In U.S. conventional poultry production, antimicrobials are used for therapeutic, prophylactic, and nontherapeutic purposes. Researchers have shown that this can select for antibiotic-resistant commensal and pathogenic bacteria on poultry farms and in poultry-derived products. However, no U.S. studies have investigated on-farm changes in resistance as conventional poultry farms transition to organic practices and cease using antibiotics. Objective: We investigated the prevalence of antibiotic-resistant Enterococcus on U.S. conventional poultry farms that transitioned to organic practices. Methods: Poultry litter, feed, and water samples were collected from 10 conventional and 10 newly organic poultry houses in 2008 and tested for Enterococcus. Enterococcus (n = 259) was identified using the Vitek ® 2 Compact System and tested for susceptibility to 17 antimicrobials using the Sensititre™ microbroth dilution system. Data were analyzed using SAS software (version 9.2), and statistical associations were derived based on generalized linear mixed models. Results: Litter, feed, and water samples were Enterococcus positive. The percentages of resistant Enterococcus faecalis and resistant Enterococcus faecium were significantly lower (p <0.05) among isolates from newly organic versus conventional poultry houses for two (erythromycin and tylosin) and five (ciprofloxacin, gentamicin, nitrofurantoin, penicillin, and tetracycline) antimicrobials, respectively. Forty-two percent of E. faecalis isolates from conventional poultry houses were multidrug resistant (MDR; resistant to three or more antimicrobial classes), compared with 10% of isolates from newly organic poultry houses (p = 0.02); 84% of E. faecium isolates from conventional poultry houses were MDR, compared with 17% of isolates from newly organic poultry houses (p <0.001). Conclusions: Our findings suggest that the voluntary removal of antibiotics from large-scale U.S. poultry farms that transition to organic practices is associated with a lower prevalence of antibiotic-resistant and MDR Enterococcus.

KW - Antibiotic resistance

KW - Antibiotic-resistant bacteria

KW - Antimicrobial growth promoter

KW - Enterococcus

KW - Organic poultry

UR - http://www.scopus.com/inward/record.url?scp=80455162350&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=80455162350&partnerID=8YFLogxK

U2 - 10.1289/ehp.1003350

DO - 10.1289/ehp.1003350

M3 - Article

VL - 119

SP - 1622

EP - 1628

JO - Environmental Health Perspectives

JF - Environmental Health Perspectives

SN - 0091-6765

IS - 11

ER -