The Case of E' coli O157:H7

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The Case of E. coli O157H7
On the Farms

• Francisco Diez
• Department of Food Science and Nutrition
• Staff Development Conference
• May 15, 2001

2
E. coli in the News
3
E. coli

• Escherichia coli O157H7
• Subtype of enterohemorrhagic E. coli (EHEC)
• Food- and water-borne pathogen
• Causes bloody diarrhea, intestinal cramps,
  vomiting and, hemolytic uremic syndrome

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Food-borne Pathogenic E. coli
Other E. coli
E. coli O157
Non-O157 EHEC
ETEC
Total E. coli infections 173,000 per year
(Mead, et al. 1999)
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Food-borne Pathogenic E. coli

• Deaths Costs
• (per year) ( billion)
• Total 78 1.0
• O157 52 0.7
• Non-O157 EHEC 26 0.3

(ERS, 2000)
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Pathogen-associated Food Recalls - 2000
Other
Salmonella
Listeria monocytogenes
E. coli O157
Total pathogen-associated recalls 126
(SafetyAlerts http//www.safetyalerts.com)
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Emergence of E. coli O157
50
40
30
Outbreaks per year
20
10
0
80
82
84
86
88
90
92
94
96
98
Year
(Data taken from Armstrong et al., 1996
USDAAPHIS, 1997 CDC, 1999, 2000)
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E. coli O157s Natural Reservoir
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E. coli O157 - Prevalence in Cattle

• O157-Positive
• Median Range
• Overall 2 0 - 63
• Overall (w/IMS) 30 10 - 68
• IMS immunomagnetic separation

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E. coli O157 - Infection Routes
Manure
Meat
Apples
Vegetables
Water
Milk
Ground beef
Juice
Salami
Cheese
Yogurt
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E. coli O157- On Farm Control Strategies

• 1. Reduce fecal shedding in cattle
• Improved sanitation and HACCP
• Vaccination
• Change in diet
• Competitive exclusion
• Feed additives
• 2. Treatment and control of manure

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Improved Sanitation and HACCP

• Identification of risk factors
• Components in diet
• Cleaning procedures
• Space per animal
• Age
• Identification of CCPs
• Setting of control limits

13
E. coli O157- On Farm Control Strategies

• 1. Reduce carriage in cattle
• Improved sanitation and HACCP
• Vaccination
• Change in diet
• Competitive exclusion
• Feed additives
• 2. Treatment and control of manure

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Vaccination

• In mice
• Stimulated immunological response, but did not
  protect against colonization
• Conlan, et al. (1999, 2000)
• In calves
• Promote anti-O157 reaction in serum, but no
  difference in fecal shedding
• Jordan and McEwen (unpublished)

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E. coli O157- On Farm Control Strategies

• 1. Reduce carriage in cattle
• Improved sanitation and HACCP
• Vaccination
• Change in diet
• Competitive exclusion
• Feed additives
• 2. Treatment and control of manure

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Switch from grain- to hay-feeding
-4 -2 0 2 4 6 8
10 12
(Diez-Gonzalez et al., 1998)
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Corn vs. Hay Controversy Summary

• For total E. coli
• Hay-fed animals have lower numbers
• For E. coli O157H7
• In artificially inoculated animals
• No difference or hay-fed cattle shed it longer
• In naturally infected cattle
• Hay reduced incidence

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Feasibility of Hay-feeding for E. coli O157
Control

• Advantages Disadvantages
• Simple Decreases productivity
• Natural Requires feeding system changes

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E. coli O157- On Farm Control Strategies

• 1. Reduce fecal shedding in cattle
• Improved sanitation and HACCP
• Vaccination
• Change in diet
• Competitive exclusion
• Feed additives
• 2. Treatment and control of manure

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Competitive Exclusion

• Use of antagonistic bacteria to reduce E. coli
  O157 intestinal colonization
• Mediated by the production of inhibitory proteins
  (colicins)
• In chickens, Preempt System against Salmonella

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Competitive Exclusion vs. E. coli O157 in Cattle

• By feeding 17 E. coli strains to
  artificially-inoculated calves
• 1) Reduced shedding time
• 2) Less O157 found in tissues
• (Zhao et al., 1998)

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Development of a Competitive Exclusion System at
the University of Minnesota

• Identified 25 recently-isolated anti-O157
  colicinogenic E. coli strains
• Select strains that produce colicins not normally
  present in cattle to
• Feed to O157-carrying cattle
• Develop colicinogenic maize plants

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E. coli O157- On Farm Control Strategies

• 1. Reduce fecal shedding in cattle
• Improved sanitation and HACCP
• Vaccination
• Change in diet
• Competitive exclusion
• Feed additives
• 2. Treatment and control of manure

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Feed Additives

• Sodium Chlorate
• Nymoxs antibacterial agent, NXC 4720
• Use of bacteriophages

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E. coli O157- On Farm Control Strategies

• 1. Reduce fecal shedding in cattle
• Improved sanitation and HACCP
• Vaccination
• Change in diet
• Competitive exclusion
• Sodium chlorate
• 2. Treatment and control of manure

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Treatment of Cattle Manure with Sodium Carbonate
10
Control
8
Sodium Carbonate Sodium hydroxide (4 and 2 g/kg)
Escherichia coli
6
(log
cells/ml)
10
4
2
0
0
2
4
6
8
10
Time (days)
(Diez-Gonzalez, et al., 2000)
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Treatment of Cattle Manure with Sodium Carbonate

• Optimization of sodium carbonate/hydroxide/urea
  combinations
• Simulation of manure handling practices

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Are we going to find a solution to the E. coli
food safety problem?

• An integrated solution Farm to Table