Prevalence of Salmonella on young chicken carcasses in the U.S.:

1999-2000

Denise R. Eblen and L. Victor Cook.USDA/FSIS/OPHS, Biosciences Division, Microbiology Branch, Washington DC.

Abstract

The U.S. Dept of Agriculture Food Safety and Inspection Service (USDA-FSIS) recently completed a one-year prevalence study of Salmonella spp. on young chicken carcasses from November 1999 to October 2000.

The prevalence of Salmonella was 8.7%; variables considered included plant size and geographical location.

Background

Data were extracted from a one-year prevalence study of Salmonella spp. on young chicken carcasses from November 1999 to October 2000, and from the Pathogen Reduction (PR) HACCP data collection program from the same period.

These programs were initiated by USDA-FSIS to estimate the prevalence of Salmonella on young chicken carcasses as currently produced, and to verify that establishments are meeting PR-HACCP standards, respectively.

Objectives

To compile nationwide data that provide a profile of Salmonella prevalence in young chickens.

To use the information and knowledge gained from these programs as a reference for further investigations and evaluation of new pathogen reduction programs.

Program Design

Data from two differently designed studies are included here. •The Nationwide Young Chicken Microbiological Baseline Data Collection Program establishes an updated profile of Salmonella in young chickens as currently produced under Federal inspection. The results on the presence of Salmonella are expressed as a national average relative to slaughter volume. This approach is similar to the earlier FSIS Nationwide Microbiological Baseline Data Collection Programs for steers and heifers, cows and bulls, market hogs, broiler chickens, and young turkeys.

•PR/HACCP Program: To verify that industry PR/HACCP systems are effective in controlling the contamination of raw meat and poultry products with pathogens, the PR/HACCP rule sets Salmonella performance standards that slaughter establishments and establishments that produce raw ground products should meet. The performance of establishments under federal inspection was assessed by having federal inspection personnel collect randomly selected product samples, and sending them to FSIS laboratories for Salmonella analysis. The PR-HACCP data presented here represents data from “A” sample sets. The results from follow-up testing resulting from failed “A” sample sets (that is, the results from subsequent “B” and “C” sets) are not included because they do not represent a random sampling of establishments. Data for large and small plants only are included for 1999; HACCP was not introduced in very small plants until 2000.

FSIS Definition of Establishment Size

Large: 500 or more employees

Small: 10-499 employees, unless annual sales total less than $2.5 million

Very small: Fewer than 10 employees, or annual sales of less than $2.5 million.

Methodology

All samples were aseptically collected by FSIS Inspectors-in-Charge following the procedures in FSIS Directive 10,230.5 (2/4/98).

Briefly, for each sample, one randomly selected post-chiller whole young chicken carcass was aseptically placed into a sterile bag and shaken with 400 ml pre-chilled Buffered Peptone Water (BPW).

Once the contents of the bag were properly mixed, two sterile screw-cap containers with lids were each filled with 100 ml of rinse fluid, i.e. a total of 200 ml rinse was submitted for analysis.

Duplicate portions of the carcass rinse were used for each of the ensuing microbiological analyses and were shipped to the designated laboratory via an overnight delivery service.

Thirty ml sterile single-strength BPW BPW was added to 30 ml of carcass rinse fluid from the sample container to bring the total volume to 60 ml. Procedures for the qualitative analysis of Salmonella were followed according to the instructions in Chapter 4 of the FSIS Microbiological Laboratory Guidebook, beginning at

Section 4.45c.

Breakdown of US by geographical region

- includes Alaska, Guam, Hawaii, Puerto Rico and the US Virgin Islands

Results

Prevalence of Salmonella (non-Typhi) in tested portions of young chicken carcass rinse fluids. Samples collected Nov 1999- Oct 2000.

no. of n no. Prevalenceestablishments positive (%)

Nationwide 205 1225 107 8.7 prevalence study

PR-HACCP 187 9302 813 8.7

As a result of the low production levels, no samples were collected in 4. No positive samples collected in region 1.

4.67

3.74

3.74

2.80

11.21

3.744.67

69.16

2 3 5 6 7 8 9 Not recorded

n= 1225; samples positive for Salmonella = 107

Contribution of each region (%) to the overall no. of samples positive for Salmonella. Nationwide prevalence study data,

Nov. 1999 - Oct. 2000.

Region

Region

Contribution of each region (%) to the overall no. of samples positive for Salmonella. PR-HACCP data,

Nov. 1999 - Oct 2000.

59.29

0.49 8.121.85

4.18

3.08

23.99

2.46

1 2 3 5 6 7 8 9

n = 9302; samples positive for Salmonella = 813

As a result of the low production levels, no samples were collected in region 4

Contribution of each region (%) to the overall no. of samples tested. Nov. 1999 - Oct 2000.

Nationwide prevalence study samples

PR-HACCP samples

Region

68.90

5.31

0.908.00

3.1010.12

0.653.02

12

3456

789

Not recorded

68.44

2.23

1.61

6.814.4513.96

1.910.59

As a result of the low production levels, no samples were collected in region 4

Salmonella prevalence within regions

0

5

10

1520

25

30

35

40

1 2 3 4 5 6 7 8 9

Region

% p

ositi

ve fo

r

Salm

onel

la

PR-HACCP data Nationwide prevalence study

Data presented are percentages of positive Salmonella samples expressed as a percentage of the total no. of samples collected in that region, with actual no. of positives indicated on the chartDue to low production volume, no samples were collected in region 4 in either study, and no samples were collected in region 9 during the Nationwide baseline prevalence study (Ø).

20

665

15 4

20

4

8 3482

74195

1225

Ø Ø Ø

976

199

14979

23 0 50

200

400

600

800

1000

1200

Large Small Very Small Not recorded

no. o

f sam

ples

total no. of samples tested Salmonella detected

6465

2632

52 153461 315

16 210

1000

2000

3000

4000

5000

6000

7000

Large Small Very Small Not recorded

no. o

f sam

ples

total no. of samples tested Salmonella detected

Total no. of samples collected*, and no. of positive Salmonella samples detected**,

in plants of different sizesNationwide prevalence

study

PR-HACCP data

**

*

Contribution of plant size (%) to the total no. of samples tested

Nationwide prevalence

study

PR-HACCP data

69.50

28.29

1.640.56

81.67

16.65

1.68

Large

Small

Very small

Notrecorded

*Only 1 very small plant (0.08% of total establishments

visited) was included in the Nationwide prevalence study.

*

Percentage of samples, within plants of different sizes, which tested positive for Salmonella

0

5

10

15

20

25

30

35

Large Small Very small Not recorded

Plant Size

% o

f sam

ples

test

ed th

at w

ere

posi

tive

for

Salm

onel

la

Nationwide prevalence study PR HACCP

976*6465

199 2632

1

52

49153

*total number of samples collected in each sized establishment

A news release (4-18-02) from USDA stated that the prevalence of Salmonella in young chickens has decreased in comparison to studies conducted prior to implementation of PR/HACCP implementation. This statement is supported by the data presented here.

Differences in pre- versus post-HACCP Salmonella prevalence, which was approx. 20% when measured in 1994-1995, may reflect changes due to HACCP implementation. This observed decrease in Salmonella prevalence correlates with reports from the Centers for Disease Control and Prevention indicating a decline in human illness linked to Salmonella during the same time period.

Summary

Many thanks are due to the FSIS Inspectors-in-Charge, who were responsible for collecting the samples, and to the staff at the FSIS Field Service Laboratories in Athens, GA., St. Louis, MO and

Alameda, CA, in particular the microbiologists who were responsible for sample analysis.Sincere thanks to Bob Umholtz of LSDMS, OPHS, for assistance in compiling

the data for this presentation.

“..Salmonella prevalence levels (are) well below the product baselines set prior to

HACCP. This indicates that HACCP has contributed to a reduction in the

prevalence of Salmonella in the nation’s meat and poultry products”.

Ann Veneman, Secretary for Agriculture, April 18, 2002

“While the prevalence of Salmonella in meat and poultry products has declined,

USDA is continuously working to further reduce the prevalence of pathogens in

meat and poultry, and to improve food safety at each step of food production,

from farm to table”.Elsa Murano, Undersecretary for Food Safety, April 18, 2002.

Quotes