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Laney Graduate School

Emory College

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Antibiotic resistance associated with small-scale poultry farming in rural Ecuador

Grossman, Marissa (2012)
Master's Thesis (56 pages)
Committee Chair / Thesis Adviser: Levy, Karen
Committee Members:
Research Fields: Health Sciences, Public Health; Environmental Sciences
Partnering Agencies: University, college or educational institution (other than Emory)
Keywords: antibiotic resistance; poultry; farming; Ecuador; agriculture
Program: Rollins School of Public Health, Environmental Health (Global Environmental Health - MD & MPH )
Permanent url: http://pid.emory.edu/ark:/25593/br70k

Abstract

Background: Antibiotic resistance poses a significant health threat worldwide.
Many studies have investigated the impacts of animal antibiotic use in large
industrial settings, yet very few have looked that the effects in small-scale farms. It
is important to understand the dynamics of resistance spread in small-scale settings,
especially in developing countries where the risk of bacterial transmission is higher
due to inadequate sanitation and hygiene practices. The main goal of this study is to
understand the impact of small-scale poultry farming on antibiotic resistant bacteria
in the environment to determine potential mechanisms of resistance transmission
between chickens and humans. Methods: Environmental samples (soil, drinking
water, and kitchen surfaces) were collected from houses in rural Ecuador that either
actively raised chickens in their backyard, previously raised chickens, or never
raised chickens. If the household raised chickens, chicken coop soil and surfaces
were also collected. Samples were also taken from one village that had a collective
community farm located away from the houses. This village switched to backyard
farming during the study, providing a useful comparison of farming operations. E.
coli was isolated from all samples and tested for resistance against a panel of 12
antibiotics. The outcomes considered for analysis were resistance to
fluoroquinolones, antibiotics used in chickens in the study area, and multidrug
resistance. Results: There were extremely high levels of resistance in the coop area
of the community farm. Approximately 50% were resistant to fluoroquinolones and
67% were resistant to chicken antibiotics and multidrug resistant, which is roughly
equivalent to estimates from chickens in industrial broiler facilities. In addition,
there were higher levels of resistance in the indoor environment in houses that had
backyard farms than those with the community farm. This suggests the proximity of
the farm to the household is a factor in potential spread of resistant bacteria.
Conclusion: Intensive use of antibiotics in small-scale operations is associated with
high levels of resistant bacteria, and the potential for transmission of resistant
bacteria is heightened when the farm is in the backyard.




Table of Contents

Introduction................. 1

Methods................. 6

Study Area........... 6

Village and Household selection........... 7

Sample Collection & Laboratory Analysis........... 9

Statistical Analysis........... 13

Results................. 15

Overall prevalence of antibiotic resistance in environmental samples........... 16

Comparison of antibiotic resistance prevalence based on household farming status........... 19

Comparison of antibiotic resistance prevalence between backyard farms and a community farm........... 21

Antibiotic resistance prevalence in Punta de Piedra........... 23

Factors associated with resistance in environmental samples........... 25

Discussion................. 27

Conclusion................. 32

References................. 33

Appendix A: Household Survey................. 36

Appendix B: Survey for households actively raising chickens................ 43

Files

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