Manan SharmaEnvironmental Microbial and Food Safety

Laboratory, USDA-ARSHenry A. Wallace Beltsville Area Research

Center, Beltsville MDSeptember 11 2013

Produce Safety

ARS Administrator’s Council Meeting

What is in your salad?

• Estimated 48 million cases of foodborne illnesses a year– 125,00 hospitalizations– 3,000 deaths

• CDC estimates that 44% of cases of foodborne in the U.S. result from the consumption of contaminated produce

• In the last decade, high profile produce outbreaks with Escherichia coli O157:H7, Salmonella spp., Listeria monocytogenes, Cyclospora cayetanesis

Foodborne / Produce illness costs in the U.S.

• Average cost per case of foodborne illness in the U.S: $1851

• Average cost per case of produce-related foodborne illness in the U.S. : $1961

• Average cost of an E. coli O157:H7

infection in the U.S: $6256 (USDA ERS, 2007)

Annual Estimated Cost ($152 billion) of foodborne illness

in the U.S.Scharff 2010

Foodborne illness in U.S. (non-produce attributed)

Produce-associated foodborne illness

$38 billion

$114 billion

Incidence of Produce-associated outbreaks

• 5% of foodborne outbreaks from 1973-2006 related to leafy greens (LG)– 9% caused by E. coli O157:H7– 10% caused by Salmonella– 60% caused by norovirus

• Since 1990:– 13 outbreaks of salmonellosis on tomatoes (grape,

roma) causing 2110 reported cases (CDC, 2007)• Estimated that 97% cases of salmonellosis are NOT reported

Recent Leafy Green Outbreaks / Recalls

• Bagged spinach and lettuce (2006) – E. coli O157:H7– “Watershed” moment– over 200 people sickened,

4 deaths, $1 billion loss to leafy greens industry

• Romaine lettuce (2010)– E. coli O145, multi-state –

34 illnesses

• Romaine lettuce? (2010)– Salmonella ?, multi-state,

71 illnesses

Leafy Green and Sprout Outbreaks

Outbreak Cases of E. coli O157:H7 infections

Hospitalization rate

Cases of Hemolytic Uremic Syndrome

Bagged Spinach ’06 – U.S.

183 95 (52%) 29 (16%)

Shredded Lettuce ’06 – U.S.

71 53 (75%) 8 (11%)

Romaine Lettuce ‘10 (O145) – U.S.

30 12 (40%) 3 (10%)

Fenugreek sprouts (Germany) ‘11

3253 - 785 (24%)

Averages for E. coli O157:H7 outbreaks

- 30% 5- 10 %

51 deaths

Fenugreek Sprout Outbreak 2011, Germany and France

• Escherichia coli O104:H4– 3908 cases, 785

cases of hemolytic uremic syndrome (HUS), 53 deaths so far

– Seeds sprouted at organic farm in Bienenbüttel, Germany (from Egypt)

• Sprouts continue to be involved in numerous outbreaks in the U.S. (1990’s, 2000’s)

• Conditions to grow sprouts are extremely conducive to bacterial growth

2011• Rocky Ford cantaloupes

(Jensen Farms, CO)–Old equipment / improper washing practices led to cantaloupes becoming contaminated with Listeria monocytogenes, killing 35 people–Lack of sufficient sanitizer in wash water and poor equipment design

2012• Chamberlain Farms

(Indiana)• Gross environmental

contamination led to 261 cases of illness and 3 deaths due to Salmonella Typhimurium and Newport

• Lack of sanitizer in water, poor handling facility maintenance, and equipment was not easily accessible to be cleaned

• Packing warm melons

Recent Cantaloupe Outbreaks

Cyclospora cayetanensis – Summer 2013

• Cyclospora - parasite• Summer 2013 – outbreak

associated with bagged leafy greens – Taylor Farms de Mexico

• 646 persons ill with cyclosporiasis (8% hospitalization rate)

• Route of contamination unclear – exposure of produce to human feces, or infected food handler?

• Cyclospora only carried in humans

• Cyclospora has normally 1 week incubation period before onset of symptoms – watery, explosive diarrhea, other gastrointestinal symptoms

Food Safety Modernization Act

• Most important food safety legislation in 70 years

• Gives FDA ability to prevent outbreaks rather than respond to them

• Establishes science-based standards for produce harvesting/production

• Mechanisms to hold food companies accountable for food that is produced in a specific facility

Food Safety Modernization Act 2011

Preventive Controls for Human Food

Standards for Produce Safety

E. coli O157:H7 (does not ferment sorbitol)

non-O157 E. coli (ferments sorbitol)

-

E. coli O157:H7 and non- E. coli O157:H7 isolated from lettuce (left) and manure-amended soil (right)

E. coli O157:H7

Escherichia coli O157:H7 (EHEC)

• Multiple virulence mechanisms makes it a hardy and versatile pathogen– Shiga toxin (stx1 and

stx2) – cause of hemolytic uremic syndrome (HUS)

– A/E lesions (eae) – allows intimate attachment to intestinal cells – cause of diarrhea Fraser, M.E., Fujinaga, M., Cherney, M.M., Melton-Celsa, A.R., Twiddy, E.M., O`Brien,

A.D., James, M.N.G. Structure of Shiga Toxin Type 2 (Stx2) from Escherichia coli O157:H7. J.Biol.Chem. v279 pp. 27511-27517, 2004 [ Abstract ]

The EMBO Journal (1998) 17, 2166–2176, doi:10.1093/emboj/17.8.216

E. coli O157:H7

Assessing survival of enteric pathogens in field environments

• Collaborative study between FDA, USDA ARS and University of Maryland Eastern Shore

• Compare the survival of attenuated (stx-negative) E. coli O157:H7 to non-pathogenic E. coli in animal manures at several different sites in the Mid-atlantic region

• Determine if the 270-day period (FDA proposed rule) from manure application to harvest of produce crop is sufficient to prevent transfer of enteric pathogens to produce crops

Manure Pathogen Survival Study (MPSS)

• Use attenuated O157 and non-pathogenic E. coli strains isolates which had been isolated from produce-growing environments (Suslow, UC-Davis)

• Spread manure (solid or liquid) to conventional or organic soils, and then spray manure with non-pathogenic / O157- E. coli at either low or high populations

Southeast Agricultural Research & Extension Center (SEAREC), Manheim, PA Soil type: Hagerstown silt loam (SL)

University of Maryland Eastern Shore, Princess Anne, MDSoil type: Othello silt loam

USDA ARS, Beltsville Area Research Center, Beltsville MDSoil type: Keyport and Matawan Organically- and conventionally-managed plots

Survival of O157 and non-pathogenic E. coli at high populations in poultry litter-amended conventional soils

at USDA ARS BARC, Beltsville, MD

Non-pathogenic E. coli

0 7 14 21 28 35 42 49 560.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00Conv surfaceConv till

Days

Lo

g C

FU

/g d

ry w

t

Rain Event – Day 6 – 0.19 in.

Attenuated E. coli O157:H7

0 7 14 21 28 35 42 49 56-1.00

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00Conv surfaceConv till

Days

Lo

g C

FU

/g d

ry w

t

FDA/NASA Survey in the Salinas Region

Session Samples E. coli O157(%) STEC(%)

Year 1 + 2 1100 98 ( 8.9) 135(12.3)

Salmonella prevalence in Salinas Valley watershed – same sites samples every 2 weeks

10/26/2

011

11/21/2

011

12/17/2

011

1/12/2

012

2/7/2

012

3/4/2

012

3/30/2

012

4/25/2

012

5/21/2

012

6/16/2

012

7/12/2

012

8/7/2

012

9/2/2

012

9/28/2

012

10/24/2

012

11/19/2

012

12/15/2

012

1/10/2

013

2/5/2

013

3/3/2

013

3/29/2

013

4/24/2

013

5/20/2

013

6/15/2

013

7/11/2

0130.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

Pe

rce

nt

of

sa

mp

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po

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ive

L. monocytogenes prevalence in Salinas Valley watershed – same sites samples every 2 weeks

11/30/1

1

12/25/1

1

01/19/1

2

02/13/1

2

03/09/1

2

04/03/1

2

04/28/1

2

05/23/1

2

06/17/1

2

07/12/1

2

08/06/1

2

08/31/1

2

09/25/1

2

10/20/1

2

11/14/1

2

12/09/1

2

01/03/1

3

01/28/1

3

02/22/1

3

03/19/1

3

04/13/1

3

05/08/1

3

06/02/1

3

06/27/1

3

07/22/1

30.00

10.00

20.00

30.00

40.00

50.00

60.00

70.00

80.00

90.00

100.00

Pe

rce

nt

po

sit

ive

sa

mp

les

Using Zero-valent Iron (ZVI) to improve irrigation wate quality

• Use a combination of sand, ZVI, and gravel to filter potentially contaminated irrigation water applied to leafy greens

• Is a “green” application to provide more sources of surface water for irrigation purposes; help increase quality of irrigation water to meet new proposed FDA standards from FSMA

Populations of E. coli O157:H12 in inoculated water filtered by either no treatment (control), sand, or sand-zerovalent iron (ZVI) and collected in a carboy before irrigation of spinach plants.

Population (log CFU /100 ml) of E. coli O157:H12 in irrigation water collected in carboys after

filtration

Treatment

Day Control Sand ZVI

0 8.29x 7.80x 2.34ay

1 0.11y 7.56x 1.75y

4 0.46y 5.85x 1.25y

6 0.85y 3.91x −0.46y

8 0.85y 3.34x −0.66y

13 < 1 y 2.84x --2Within Day, means of treatment in the same row followed by a different letter (x,y) are significantly (P < 0.05) different.3 -- indicate no E. coli O157:H12 populations were recovered.

ARS Produce Safety Collaborators

• FDA-CFSAN• University of Maryland Eastern Shore• University of Delaware• University of Maryland College Park• University of Wisconsin-Madison• University of California-Davis• North Carolina A&T State University• SEAREC (Pennsylvania State University)• Center for Produce Safety – UC-Davis

Acknowledgements

Cheryl RobertsDr. David IngramDr. Patricia MillnerDr. Jitu PatelDr. Dan SheltonSean FergusonRussell ReynellsRishi BanerjeeEric HandyMary Theresa CallahanJune deGraft HansenNatalia MacarisinDr. Fawzy HashemMs. Corrie Cotton