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Food Safety and Inspection Service Nationwide Raw Pork Product Sampling Study 

1Maria E. Scott, 1Evelyne Mbandi, 1Stephanie Buchanan, 1Naser Abdelmajid, 1Christian Gonzalez-Rivera, 2Jennifer Webb, 2Jennifer Green, 3Paul Dolan 

1 USDA-FSIS/Office of Public Health Sciences; 2 USDA-FSIS/Office of Policy and Program Development; 

3 USDA-FSIS/Office of Planning, Analysis and Risk Management 

Salmonella Results STEC Results Background 

• Undercooked pork is a known source of foodborne illness but data is lacking on the prevalence of Salmonella and 

STEC in raw pork products. 

Purpose of the Raw Pork Exploratory Baseline Study 

• Determine the National Prevalence of Salmonella in raw pork products. 

• To ascertain the presence of STEC in raw pork products and develop a risk profile. 

Methods 

Phase I (May 2015 to November 2015) – Pilot Study to Set the Parameters for the Baseline Study 

• A total of 1,200 samples, from slaughter and processing-only establishments, of comminuted, non-intact, and 

intact cuts of raw pork products were tested for Salmonella. 

• 200 of the 1,200 samples collected from slaughter and processing-only establishments were analyzed for STEC. 

Phase II (June 2017 through May 2018) – Baseline Study to address Prevalence and Risk 

• Total 4,014 raw pork samples (comminuted, non-intact, and intact cuts) from slaughter and processing-only 

establishments were tested for Salmonella. 

• Only samples from slaughter establishments were tested for top 7 STEC (1,395 samples). 

• Sample design was a stratified approach based on establishment production volume for each group of raw pork 

products, specifically comminuted, non-intact, and intact cuts. 

Phase I 

Pork 

Product 

Samples 

Percent Positive 

Serogroup of STEC Isolates 

O26 O45 O103 O111 O121 O145 Total 

Comminuted 5.4% (6/112) 1 5 1 1 1 3 12 

Intact 4.9% (4/53) 2 3 3 1 3 3 15 

Non-intact 0.0% (0/1) 0 0 0 0 0 0 0 

Intact & Non-intact 

Other 0.0% (0/34) 0 0 0 0 0 0 0 

Total 5.0% (10/200) 3 8 4 2 4 6 27 

Phase II 

Pork 

Product 

STEC 

Isolated 

Confirmed 

Positive 

Number of Samples 

Analyzed 

Comminuted 

O157:H7 1 

667 

O103 2 

Intact None 0 406 

Non-intact None 0 322 

Total 3 1,395 

Summary of Results 

Phase I [Pilot study] 

The Top Five Serotypes of Salmonella Identified 

Rank 

Phase I Phase II 

Salmonella Number of Isolates 

Serotypes Recovered 

Salmonella Number of Isolates 

Serotypes Recovered 

1 

2 

3 

4 

5 

5 

Derby 25 

Anatum 23 

Infantis 17 

Johannesburg 12 

I 4, [5],12:i:- 11 

Typhimurium 11 

Anatum 75 

Infantis 71 

Johannesburg 49 

Derby 47 

I 4, [5],12:i:- 33 

----

Percent Antibiotic Resistance of Salmonella Isolates Recovered 

Phase I Phase II 

Salmonella isolates 

recovered 

Percent antibiotic 

resistance markers 

Salmonella isolates 

recovered 

Percent antibiotic 

resistance markers 

200 

48% 

(96/ 200 isolates) 545 

32% 

(174/545 isolates) 

• Of the 1200 samples collected, 200 tested positive for Salmonella (16.7%). 

• Of the 200 samples tested for STEC, 10 samples confirmed positive 

resulting in 27 independent STEC isolates recovered. 

21.0% 

11.9% 

5.0% 

18.7% 

7.5% 

21.2% 

8.3% 6.5% 

25.0% Sample and Bacterial Isolate Testing 

• FSIS-Microbiology Laboratory Guidebook methods for raw pork sample analysis. 

• Antibiotic susceptibility according to National Antimicrobial Resistance Monitoring System (NARMS). 

• Illumina MiSeq Sequencer using Pulse Net standard procedures with Nextera XT library for the Illumina. 

• Antibiotic resistance genetic markers determined via U.S. National Library of Medicine, National Center for 

Biotechnology Information Database Pathogen Browser with the Antibiotic Resistance Isolate Bank hosted by 

CDC and the FDA. 

• Statistical software WesVar v 5.1 was used to calculate the national prevalence (weighted average) of Salmonella 

within the U.S. raw pork industry. 

Salmonella % Positives 20.0% 

• Seventeen of these isolates were recovered from processing establishments 

and 10 from slaughter establishments. 

Phase II [Baseline study] 

• National Prevalence of Salmonella was 29% for comminuted, 5% for intact 

cuts, and 4% for non-intact cuts. 

• Three STEC isolates were recovered. 

15.0% 

10.0% 

5.0% 

0.0% • Comminuted pork products had the highest prevalence of Salmonella. Comminuted Intact Cuts Non-Intact Cuts Intact Other Non-intact 

Other • Data suggest fabrication and processing augmented the levels of pathogens. Raw Pork Product Categories Phase 1 Phase II 

Significance of the Work • Comminuted (Ground, Other Comminuted, Advanced Meat Recovery, Mechanically Separated, Sausage, Patties, 

Phase II Salmonella Results 

Product Samples Analyzed Percent Positive National Prevalence Confidence Interval 

Comminuted 

Intact 

Non-intact 

1,796 

1,170 

1,048 

21.2% (380) 

8.3% (97) 

6.5% (68) 

28.9% 

5.3% 

3.9% 

24.1% - 33.8% 

4.3% - 6.4% 

0.6% - 7.2% 

Total 4,014 13.6% (545) 

• Salmonella associated with raw pork products is a public health concern. 

• Data from this study will be used to develop standards or policies to 

reduce the levels of Salmonella in raw pork products. 

• Further investigation is warranted to determine if STEC is an emerging 

public health concern in raw pork products. 

Next Steps 

• Review current policies as they apply to efforts to mitigate levels of 

and Other Formed Products). 

• Intact Cuts (bone-in and boneless). 

• Non-intact Cuts (bone-in and boneless tenderized or injected). 

• Intact and Non-Intact Other [Phase I only] (Feet, Neck Bones, and Cutlets not tenderized or injected). 

Proposed Sample Allocation for Raw Pork Product Groups Phase II 

Pork Product Strata 

Eligible Establishments Sampling Frequency Proposed # of Samples 

Total # Sampled % Included Month Year to Be Collected 

Comminuted 

≥1,000,000 lbs.

>90,000 up to 1,000,000 lbs. 

>10,000 up to 90,000 lbs. 

25 25 100.0% 

99 50 50.5% 

129 80 62.0% 

2 24 

1 12 

0.5 6 

600 

600 

480 

Total 253 155 61.2% 1,680 

Intact 

≥1,000,000 lbs.

>90,000 up to 1,000,000 lbs. 

>10,000 up to 90,000 lbs. 

20 20 100.0% 

45 20 44.4% 

113 90 79.6% 

2 24 

1 12 

0.5 6 

480 

240 

540 

Total 178 130 73.0% 1,260 

Non-Intact 

≥1,000,000 lbs.

>10,000 and <1,000,000 lbs. 

9 9 100.0% 

36 34 94.4% 

4 48 

2 24 

432 

816 

Total 45 43 95.5% 1,248 

Total Samples Projected for Phase II (Baseline study) 4,188 

References 

1. United States Department of Agriculture, Food Safety and Inspection Service. Microbiology Laboratory Salmonella in raw pork products. 

Guidebook. Available at: https://www.fsis.usda.gov/wps/wcm/connect/fsis- • Continue to monitor levels of Salmonella in these products. content/internet/main/topics/science/laboratories-and-procedures/guidebooks-and-methods/microbiologylaboratory-guidebook/microbiology-laboratory-guidebook • Use data collected to conduct multivariate analysis of Salmonella data to 

help identify factors that contribute to high levels of Salmonella in raw 2. National Antimicrobial Resistance Monitoring System. Manual of Laboratory Methods. Available at: pork products. https://www.fda.gov/downloads/AnimalVeterinary/SafetyHealth/AntimicrobialResistance/NationalAntimicrobial 

ResistanceMonitoringSystem/UCM528831.pdf • Use data generated as support for a risk profile that explains possible 

public health risk of STEC in raw pork products. 3. Whole genome sequencing using laboratory standard operating procedure for PulseNet NexteraXT library 

preparation and setup for Illumina MiSeq. Available at: https://www.cdc.gov/pulsenet/pdf/PNL32-MiSeq- Acknowledgements: The authors recognize the many FSIS individuals responsible Nextera-XT.pdf for making a baseline study like the Raw Pork Product Sampling Program successful. 

4. National Institutes of Health, United States Library of Medicine, National Center for Biotechnology Information, A special recognition goes to the Office of Field Operations/Inspection Program pathogen browser to identify genetic markers. Available at: https://www.ncbi.nlm.nih.gov/pathogens/isolates/ Personnel and those at Headquarters (HQ); Office of Public Health Science/Field 

5. Center Antibiotic Resistance Isolate Bank hosted by CDC and the Food and Drug Administration. Available at: Service Laboratories and HQ staff; Office of Policy and Program Development; as 

https://wwwn.cdc.gov/AVIsolateBank/GeneGlossary well as the Office of Planning, Analysis, and Risk Management and others.