Antibiotic resistance of enteric bacteria in commercial broiler chickens in the Fraser Valley, BC

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Antibiotic resistance of enteric bacteria in
commercial broiler chickens in the Fraser Valley,
BC

• Nancy de With, DVM MSc
• Veterinary Epidemiologist
• BC Ministry of Agriculture and Lands

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Introduction

• The use of antibiotics in poultry has been
  associated with increased AMR in enteric bacteria
  
• Resistant bacteria (or genetic determinants of
  resistance) can be transmitted from animals to
  humans
• Food chain
• Environmental contamination

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Study Objectives

• To observe the pattern of AMR over time in
  enteric bacteria collected from freshly voided
  feces of commercial broiler chickens
• To collect farm data regarding the feeding of
  poultry foods containing antimicrobials
• To observe the pattern of AMR in isolates
  collected from broiler carcasses at slaughter

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Enteric Bacteria

• Organisms of interest
• Escherichia coli
• Salmonella spp.
• Campylobacter spp.
• Enterococcus spp.

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Study

• 11 commercial broiler barns on 9 farms
• 9 medicated barns
• 3 medicated feed regimes
• 2 non-medicated barns
• 5 visits
• days 1, 14, 26, 37 (feces)
• carcass swab at slaughter

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Study

• Samples collected Sept 2003 to Jan 2004
• Feces and carcass samples were pooled into 1 or 2
  pools for each barn and visit
• Standard lab procedures used to isolation and
  growth of each bacteria
• 5 colonies of each bacteria were selected and
  used for AMR testing using the SensititreTM (Trek
  Diagnostic Systems Ltd.)
• MIC values were obtained

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Antibiotics the NARMS plate

• Amikacin
• Amoxicillin/Clavulanic Acid
• Ampicillin
• Cefoxitin
• Ceftriaxone
• Ceftiofur
• Cephalothin
• Chloramphenicol
• Ciprofloxacin
• Gentamicin
• Kanamycin
• Nalidixic Acid
• Streptomycin
• Sulfamethoxazole
• Tetracycline
• Trimethoprim/Sulfamethoxazole

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Results

• A total of 475 E. coli, 370 Enterococcus, 40
  Salmonella, and 8 Campylobacter isolates were
  recovered
• E. coli and Enterococcus were found from all
  barns and all visits
• Salmonella were found from 2 barns/farms
• Campylobacter was found in one barn/farm

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NARMS Plate E. coli Results
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Frequency distribution of all isolates across
levels of MDR
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Poultry Feeds

• 3 feed companies (Feed Mill A, B C) supplied
  the 9 barns that received medicated feed
• Feed Mill A and Feed Mill C supplied the 2 barns
  that received non-medicated feed

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Medications in Poultry Feeds
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More on Medicated Feeds

• Medicated feed was used in accordance with the
  CMIB (administered by CFIA)
• Prevent necrotic enteritis (virginiamycin,
  bacitracin)
• Prevent coccidiosis (narasin, nicarbazin,
  salinomycin, monensin)
• Growth promotion (penicillin)
• Stimulate appetite and maintain weight gain
  (oxytetracycline, bacitracin)
• Nicarbazin has a 4-day withdrawal time and
  oxytetracycline has a 7-day withdrawal

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Conclusions

• Chicks came on to farms with more resistance than
  expected
• Few identifiable trends
• Management factors were not considered
• Would like to look at source flocks

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Acknowledgments

• BC MAL
• S. Byrne
• E. Whitton
• J. Osei-Appiah
• D. Lightfoot
• L. Lindahl
• M. Wetzstein
• H. Hannah
• J. Waddington

• Others
• D. Léger
• C. Stephen
• S. Ritchie
• R. Reid-Smith

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