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| Microbiological Testing Program for Escherichia coli O157:H7 |
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Summary Data
Summary tables containing data from 1994 forward are also available.
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Objectives of the Testing Program
On October 17, 1994, FSIS began a microbiological testing program to detect Escherichia coli O157:H7 in
raw ground beef. The objectives of the testing program have evolved over time. An original objective was
to stimulate industry testing and other actions to reduce the presence of the pathogen in raw ground beef.
Today, FSIS considers product sampling to be one of several activities conducted to verify the effectiveness of
HACCP systems. Since the initiation of the FSIS testing program, many grinders and suppliers of raw ground beef
components have instituted programs to routinely test their ground beef products or raw materials used in
ground beef products for E. coli O157:H7.
Changes Over Time
Over time, FSIS has taken steps to improve the public health effectiveness of this testing program by
detection of lower numbers of this pathogen through increased sample size and adoption of new more sensitive
methods (see footnotes that accompany Tables 1 through 5).
All regulatory analyses of raw ground beef and raw ground beef products are performed in FSIS laboratories
located in Alameda, CA, St. Louis, MO, and Athens, GA and have been reported as of sample analysis completion date.
Therefore, all text, tables and graphs through 2007 were based upon sample analysis completion date. Beginning
in 2008, quarterly and annual reports and figures are based upon sample collection date. Weekly reports are
still posted by analyses completion date due to overlapping from one week to the next.
Today, there are approximately 1,400 federally inspected establishments producing raw ground beef subject to
9 CFR 319.15 (a), (b), or (c),
the raw ground beef products that are currently routinely sampled for E. coli O157:H7 as part of the
Agency's HACCP verification program. In recent years most raw ground beef samples have been collected at the
federally inspected establishments. The Agency still collects some samples from retail stores, but normally
only when (1) the retail store produces raw ground beef using whole muscle or trimmings from a cutting/boning
operation conducted at the store, or (2) the retail store does not maintain records of raw beef suppliers
or records documenting clear and accurate grinding logs.
In earlier years, FSIS analyzed some samples from State inspected establishments when not all State programs
had the capability to test for E. coli O157:H7. All States now have their own testing program for
raw ground beef. The number of samples analyzed from imported raw ground beef will vary depending on the
volume of imported product.
Categories of Samples Used in Reporting
In recent years, there has been increasing interest in using the E. coli O157:H7 results as an indicator
of industry trends or as a measure of program performance. For this reason, the standard table that has been
used since 1994 has been revised to illustrate two categories of samples that are collected at both Federal
establishments and at retail stores. The revised table uses the following definitions for categories of samples:
- Verification Sample from a Federal Plant: Samples that are scheduled each month by randomly selecting establishments from the current population of all raw ground beef producers.
- Routine Sample from a Retail Store: Samples that are collected by program investigators in the course of making a routine visit to a retail store.
- Follow-Up Sample: Samples that are scheduled in response to a positive finding from an initial HACCP verification sample or a routine retail sample. Sample collection may or may not be the same as the location where the initial positive sample was collected. Follow-up samples include both sampling to verify corrective action and sampling to help identify the source of the contamination.
FSIS views results from the "Verification" samples from Federal establishments as the best indicator of
the overall trend of the presence of E. coli O157:H7 in raw ground beef. For this reason the Agency
uses the percentage of positives in these samples as one of its key performance measures. Figure 1
(PDF Only) shows the graph of this performance measure on an annual basis from 2000 through 2008.
2007 Results: Actions Taken to Reduce E. coli O157:H7
When the Agency posted the results from 2006, it was noted that the results for the last quarter of 2006
represented the first time a three-month quarter result had been above 0.20 percent since April-June of 2004.
Because FSIS had the performance measure aimed at keeping the percentage of ground beef positives below 0.20 percent,
the Agency was concerned about the result showing 0.21 percent even though it seemed consistent with other
recent quarter patterns and the overall results for 2006 were the same as for 2005. At the time FSIS indicated
the Agency would closely monitor the 2007 results to assess whether there is any evidence of an increasing
trend. Because the performance measure was clearly exceeded during 2007, FSIS initiated several actions
that are summarized at http://www.fsis.usda.gov/News_&_Events/
NR_102307_01_att/index.asp.
Scheduling of Samples
The initial HACCP verification samples for federally inspected establishments are randomly scheduled each month
from the most current list of establishments producing raw ground beef. The selection process has remained
the same since the program was initiated, but the number of samples scheduled for a specific month can change.
For example, during 2007, FSIS increased the number of samples for July 2007 after an unusual number of positive
results in June. Scheduling remained at an elevated level for August through December where essentially all
establishments were scheduled every month. There was also a period from 1998 through 2002 when some scheduled
establishments were exempt from sample collection if they met certain criteria that were specified in
FSIS Directive 10,010.1,
Microbiological Testing Program for Escherichia coli O157:H7 in Raw Ground Beef
which was issued February 1, 1998.
Retail samples are not scheduled from an existing list of facilities that are producing raw ground beef.
Program investigators first select retail facilities that will be reviewed. Whether or not a raw ground
beef sample will be collected depends on what is observed during a review. FSIS procedures for retail
sampling are covered in FSIS Directive 10,010.1, Revision 1, March 31, 2004, and updated through
FSIS Notice 43-06, July 20, 2006 and through various Questions and Answers now posted with Directive 10.010.1,
Revision 1.
Seasonal Variations
The 2008 results have been added to Figure 2 (PDF Only)
which shows quarterly results for samples collected from all sources for years CY 2003 through CY 2008.
Although the second and third quarters (April–September) have traditionally been considered to be the high
season, the fourth quarter had been the highest quarter for the last three years (2005–2007) in FSIS regulatory
testing for raw ground beef. The fourth quarter of 2007 had the highest percentage of positive samples since
April–June of 2003.
Trim Sampling
On March 19, 2007, FSIS began routine verification sampling of beef manufacturing trimmings intended for use
in raw ground beef or beef patty products at the slaughter establishments that produced those trimmings.
FSIS considers it extremely critical to keep the percent positive rate for beef trim low in order to affect
the percentage of positive raw ground beef samples downward. Trim sampling was initiated with FSIS Notice 18-07,
March 1, 2007. During CY 2007, FSIS analyzed 712 trim samples for E. coli O157:H7 and found 2
positive samples (0.28 percent). FSIS Notice 68-07, October 26, 2007, initiated routine verification of
other raw ground beef components. Sampling of those other components began in late December.
FSIS recently identified the results of a year-long baseline study (PDF Only)
on boneless beef manufacturing trimmings
designated for use in raw beef and the percent positive rate was 0.68 percent. FSIS will be tracking the percent
positive rate for boneless manufacturing trimmings in FSIS verification testing and comparing results with the
baseline level. FSIS believes that the percent positive rate for boneless manufacturing trimmings should
at a minimum remain below this baseline value in order to reduce the likelihood that E. coli O157:H7
will be identified in ground beef.
2008 Results
The FSIS Microbiological quarterly and yearly postings for 2008 have been reported by sample collection date.
Prior to 2008, results were reported for analyses of samples completed by the end of the calendar year.
Beginning January 2008, results will be posted to include all samples collected within the calendar year,
to better align FSIS' activities with those of other federal partners. The Agency does not anticipate
this change to have any effect on the results presented. Therefore the 2008 results can not be compared
to results from previous years, since those results were reported by analysis end date. FSIS continues
to evaluate its E. coli O157:H7 policy and testing programs using sample results and other data sources.
In January 2008, FSIS implemented a targeted sampling program that incorporates production volume and history
of sample results in scheduling raw ground beef sampling for E. coli O157:H7 at federally inspected
establishments. Under this new verification testing program, larger volume operations will be tested more
frequently than in the past, and data from the checklists (FSIS Notice 65-07) will also be used to determine
testing frequency for establishments. The Agency also implemented a change in the laboratory testing method.
The 2008 results for ground beef have been added to Table 5,
and possible effects of the implemented changes are discussed below.
The overall percent positive of raw ground beef (RGB) samples tested for E. coli O157:H7 in CY 2008 was 0.46,
Table 5. Some of the factors identified by FSIS
as possibly contributing to the percent positive for 2008 include the following:
- Test method sensitivity: Analysis of the 2008 data by the FSIS, did not demonstrate any basis for
verifying or quantifying an increased sensitivity effect for the January 2008 changes made to the E. coli
O157:H7 testing method (i.e., the "new method" FSIS MLG 5.04). The FSIS experimental validation
study determined the new method to be as sensitive as the older method, but determining the impact on
samples would require much more extensive study.
- The industry may have implemented some changes in controlling the slaughtering process for some
segments of the slaughter, fabrication and/or grinding process.
- Most ground beef establishments are lower volume producers, and a proportionally greater number of E. coli
O157:H7 samples and positive test results are associated with these establishments relative to larger
establishments. In past years, the percentage of positive samples from the smallest plants (Category 4)
was considerably less than largest establishments (Category 1). In CY 2008, FSIS observed an increase in
the relative percentage of positive results associated with smaller plants. However, analysis of CY 2008 data
for Category 1 and 4 ground beef establishments did not confirm statistically verifiable differences for
these establishment categories.
- There could have been an increase in prevalence at pre-harvest due to unknown factors. Pre-harvest
data for hides and feces carriage rate are not available for consideration, and therefore, a definitive
conclusion about the prevalence of the pathogen pre-harvest cannot be made.
There were 53 positive samples from federal establishments, which includes follow-up sampling (0.47%). The
initial verification sample percent positive rate was 0.45% and the follow-up percent positive rate was 1.12%.
It is difficult to completely explain higher percent positive rate in follow-up samples. Positive follow-up
samples may indicate a plant with sanitation problems or a supplier with sanitation problems. There was
one import sample that tested positive (2.63%). All retail samples were confirmed negative.
2009: Bench Trim Sampling
On July 31, 2009 the Agency issued a Notice (51-09, Routine Sampling and Testing of
Beef Manufacturing Trimmings Derived from Cattle Not Slaughtered in That Establishment (Bench Trim) for Escherichia coli (E. coli) O157:H7)
designed to collect beef manufacturing trimmings and other raw ground beef or patty components in establishments
that produce trim derived from cattle not slaughtered on site.
Establishments that produce beef trimmings from cattle slaughtered on site will continue to be subjected to sampling under the Trim
Verification program, and establishments that produce other raw ground beef or patty components from cattle slaughtered on site
will continue to be subjected to sampling under the Raw Ground Beef Components program.
The purpose of Notice 51-09 (PDF Only)
is to inform inspection program personnel to begin routine sampling of bench trim for E. coli O157:H7
when they receive a sample request notice with the appropriate project code. Bench Trim results are included
in weekly and quarterly Raw Ground Beef and Component Testing Data tables and any positive findings are
included in the Individual Positive Results for Raw Ground Beef Components table.
Some additional modifications under development for the FSIS testing method that may be implemented in 2009
and may consequently have some impact on FSIS data in the future include the following:
- The use of a single 325-gram test portion (although the Agency does not anticipate increased
sensitivity for this testing).
- Modifications to N60 sampling to address stakeholder concerns. The industry contends that the FSIS
N60 testing is not as representative or robust as the industry's N60 testing. As the FSIS sampling
and laboratory sample preparation are refined to more truly represent the N60 sample, there may
be potential for some change in the observed positive sample rate.
Summary Tables
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Last Modified:
January 7, 2010 |
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