Guidance for Industry: Reducing Microbial Food Safety Hazards for Sprouted Seeds and Guidance for Industry: Sampling and Microbial Testing of Spent Irrigation Water During Sprout Production

Federal RegisterOct 27, 1999

Ask Donna

What actually matters in this document.

Text

DEPARTMENT OF HEALTH AND HUMAN SERVICES

Food and Drug Administration

[Docket Nos. 99D-4488 and 99D-4489]

Guidance for Industry: Reducing Microbial Food Safety Hazards for

Sprouted Seeds and Guidance for Industry: Sampling and Microbial

Testing of Spent Irrigation Water During Sprout Production

AGENCY: Food and Drug Administration, HHS.

ACTION: Notice.

-----------------------------------------------------------------------

SUMMARY: The Food and Drug Administration (FDA) is publishing two

related guidance documents entitled ``Guidance for Industry: Reducing

Microbial Food Safety Hazards for Sprouted Seeds'' and ``Guidance for

Industry: Sampling and Microbial Testing of Spent Irrigation Water

During Sprout Production.'' These guidances are intended to provide

recommendations to suppliers of seed for sprouting and sprout producers

about how to reduce microbial food safety hazards common to the

production of raw sprouts to ensure that sprouts are not a cause of

foodborne illness and to ensure that they comply with the food safety

provisions of the Federal Food, Drug, and Cosmetic Act (the act). The

first guidance is based largely on recommendations from the National

Advisory Committee for Microbiological Criteria for Food's report

entitled ``Microbial Safety Evaluations and Recommendations on Sprouted

Seeds'' (the 1999 NACMCF report) (Ref.1). The second guidance is

intended to assist sprouters in implementing one of the principle

recommendations (i.e., microbial testing) in the broader sprout

guidance.

DATES: Written comments may be submitted at any time, however, comments

should be submitted by December 13, 1999, to ensure adequate

consideration in preparation of revised documents, if warranted.

ADDRESSES: Submit written requests for single copies of the guidance

entitled ``Guidance for Industry: Reducing Microbial Food Safety

Hazards for Sprouted Seeds'' and/or the guidance entitled `Guidance for

Industry: Sampling and Microbial Testing of

[[Page 57894]]

Spent Irrigation Water During Sprout Production'' to the Office of

Plant and Dairy Foods and Beverages (HFS-306), Center for Food Safety

and Applied Nutrition, Food and Drug Administration, 200 C St. SW.,

Washington, DC 20204, 202-205-4200. Send one self-adhesive label to

assist that office in processing your request. The guidances are

attached to this notice as appendixes 1 and 2 and are also accessible

via the FDA home page on the Internet: http://www.fda.gov. Submit

written comments on the final guidance(s) to the Dockets Management

Branch (HFA-305), 5630 Fishers Lane, rm. 1061, Rockville, MD 20852.

FOR FURTHER INFORMATION CONTACT: Michelle A. Smith, Center for Food

Safety and Applied Nutrition (HFS-306), Food and Drug Administration,

200 C St. SW., Washington, DC 20204, 202-205-2975, FAX: 202-205-4422,

e-mail: [email protected].

SUPPLEMENTARY INFORMATION:

I. Background

Since 1995, raw sprouts have been increasingly implicated in

foodborne outbreaks. Between January 1995 and May 1999, there were 11

reported outbreaks in the United States associated with sprouts from

commercial growers, 9 of which were due to various Salmonella serotypes

and 2 to Escherichia coli O157. The number of culture-confirmed cases

in each of these outbreaks ranged from 8 to more than 500, and more

than 1,300 cases have been reported overall (Ref. 1). Alfalfa and

clover sprouts have been implicated most often, but, because all kinds

of sprouts are produced under similar conditions, all raw (uncooked)

sprouts may pose a risk. In all of the reported outbreaks, the likely

source of the pathogen was contaminated seed. However, in a large 1996

Salmonella Montevideo/Meleagridis outbreak, poor sanitation and

unhygienic practices at the sprouting facility may also have

contributed to the contamination of sprouts (Ref. 1).

Sprouted seeds represent a food safety problem because the

conditions under which sprouts are produced (time, temperature, water

activity, pH, and nutrients) are ideal for the exponential growth of

bacteria. If bacterial pathogens are present on or in the seed,

sprouting conditions are likely to encourage their proliferation (Ref.

2).

FDA and other public health officials are working with industry to

identify and implement production practices to ensure that seed and

sprouted seed are produced under conditions that are safe. While these

efforts have improved food safety awareness within the industry and

have led to a significantly better understanding of the microbial

ecology of sprout-associated foodborne illness, not all industry

segments have been reached. Traceback investigations reveal that most

of the firms associated with recent outbreaks were not using approved

seed disinfection treatments, or were not using them consistently, and

were not testing for microbial contamination during sprout production.

Although currently approved treatments can significantly reduce

pathogen levels in or on seeds, they have not been shown to completely

eliminate pathogens (Ref. 1). Consequently, outbreaks continue to

occur.

On July 9, 1999, FDA issued a consumer advisory advising all

consumers to be aware of the risks associated with eating any variety

of raw sprouts, and advising persons at high risk of developing serious

illness due to foodborne disease (children, the elderly, and persons

with weakened immune systems) not to eat raw sprouts (Ref. 3). This

advisory is updated from a previous advisory issued August 31, 1998

(Ref. 4), and was prompted by information from clover and alfalfa

sprout-associated salmonellosis outbreaks that occurred from January

1999 through May 1999.

II. Guidance

In 1997, FDA asked the National Advisory Committee for

Microbiological Criteria for Food (NACMCF) to : (1) Review the current

literature on sprout-associated outbreaks, (2) identify the organisms

and production practices of greatest public health concern, (3)

prioritize research needs, and (4) provide recommendations on

intervention and prevention strategies. On May 28, 1999, NACMCF adopted

a report entitled ``Microbial Safety Evaluations and Recommendations on

Sprouted Seeds'' (Ref. 1).

FDA is now issuing ``Guidance to Industry: Reducing Microbial Food

Safety Hazards for Sprouted Seeds'' (the sprout guidance). This

guidance incorporates some of the recommendations made by the 1999

NACMCF report. The guidance identifies the most important steps, e.g.,

use of good agricultural practices (Ref. 5), seed disinfection

treatment, and microbial testing, which the agency believes should be

implemented immediately to reduce the risk of raw sprouts as a vehicle

for foodborne illness and to ensure that sprouts comply with the Food

Safety Provision of the act (21 U.S.C. 301-397).

As noted in the sprout guidance, routine use of approved seed

disinfection treatments (such as 20,000 parts per million of calcium

hypochlorite in water) is likely to reduce the level of contamination

if present in or on seeds and, in turn, reduce the risk of foodborne

illness from the consumption of sprouted seed. However, current

approved treatments do not guarantee total elimination of pathogens. If

even a few pathogens survive a seed disinfection treatment, they can

grow to high levels during sprouting and contaminate the entire batch.

Therefore, although seed disinfection treatment is recommended,

microbial testing of spent irrigation water from each batch or

production lot of sprouts should also be conducted to prevent

contaminated product from entering the food supply.

In addition, FDA is issuing ``Guidance to Industry: Sampling and

Microbial Testing of Spent Irrigation Water During Sprout Production''

(the microbial testing guidance). This guidance is designed to assist

sprouters in designing a microbial testing program to ensure

adulterated product does not enter commerce. Specifically, this

guidance recommends testing spent irrigation water from each individual

batch or production lot of sprouts for two pathogens, E. coli O157:H7

and Salmonella. The microbial testing guidance also provides

instructions for the sampling and testing of sprouts for those

instances when it is not possible to test spent irrigation water.

However, sprouts should not be tested in lieu of irrigation water when

spent irrigation water is available.

Sprouters should be aware that the microbial testing program

described in this guidance involves a number of hazards. Microbial test

procedures should only be run by qualified personnel, in a qualified

independent laboratory that is separate from food production areas.

Additional criteria for laboratories performing these tests are

provided in the microbial testing guidance.

As more effective treatments or other food safety controls are

identified and implemented, the current recommendation to test spent

irrigation water from each batch of sprouts produced may be changed,

e.g., to periodic microbial testing as a tool for validating the

effectiveness of food safety systems.

These guidance documents do not provide detailed information on all

individual steps that should be followed in the production of seeds and

sprouts. References and resources for assistance are listed at the end

of this notice and in the broader sprout guidance. Other materials, in

the form of further

[[Page 57895]]

guidance, educational videos, etc. will be made available, as

appropriate. For example, FDA and the California Department of Health

Services, Food and Drug Branch, in cooperation with industry, are

producing a comprehensive educational video outlining sprout specific

practices, in a number of areas, including those practices recommended

in this guidance. The agency expects the video to be available in early

2000.

The guidance documents (see appendixes 1 and 2) represent FDA's

current thinking on prevention of microbial hazards in sprouted seeds.

They do not create or confer any rights for or on any person and do not

operate to bind FDA or the public. An alternative approach may be used

if such approach satisfies the requirement of applicable statutes and

regulations. Following the recommendations in this guidance will not

shield any person or any food from appropriate enforcement under the

act if adulterated food is distributed in interstate commerce. The

guidances are being distributed in accordance with FDA's policy for

Level 1 guidance documents as set out in the agency's Good Guidance

Practices, published in the Federal Register of February 27, 1997 (62

FR 8961).

FDA believes this guidance and current education and outreach

efforts will have a significant positive impact on those industry

segments that still need tools to make a safer product. The agency will

closely monitor the safety of sprouts and the adoption of enhanced

prevention practices as set out in this guidance.

Failure to adopt effective preventive controls can be considered

insanitary conditions which may render food injurious to health. Food

produced under such conditions is adulterated under the act (section

402(a)(4) (21 U.S.C. 342(a)(4))). FDA will consider enforcement actions

against seed and sprout producers who do not have effective preventive

controls in place, in particular, effective microbial testing.

On December 27, 1999, FDA plans to initiate a national field

assignment, sending investigators to sprouting facilities to test water

used to grow sprouts (i.e., spent irrigation water) and to assess the

level of adoption of preventive controls.

III. References

The following references are on display in the Dockets Management

Branch (address above) and may be seen by interested persons between 9

a.m. and 4 p.m., Monday through Friday.

1. National Advisory Committee on Microbiological Criteria for

Foods, 1999a. Microbiological Safety Evaluations and Recommendations

on Sprouted Seeds, http://vm.cfsan.fda.gov/mow/

sprouts2.html.

2. National Advisory Committee on Microbiological Criteria for

Foods, 1999b. Microbiological Safety Evaluations and Recommendations

on Fresh Produce. Food Control, 10:117-143.

3. FDA, 1999, Press Release--Consumers Advised of Risks

Associated With Raw Sprouts, P99-13, http://www.fda.gov/bbs/topics/

NEWS/NEW00684.html.

4. FDA, 1998, Talk Paper--Interim Advisory on Alfalfa Sprouts,

T98-47.

5. FDA, 1998, Guidance for Industry--Guidance to Minimize

Microbial Food Safety Hazards for Fresh Fruits and Vegetables,

http://www.foodsafety.gov/dms/prodguid.html.

IV. Comments

FDA is soliciting public comments, but is implementing this

guidance document immediately because of continuing foodborne illness

outbreaks associated with consumption of raw sprouts. Interested

persons may, at any time, submit written comments on the guidance

documents to the Dockets Management Branch (address above). Two copies

of any comments are to be submitted except that individuals may submit

one copy. Comments should be identified with the appropriate docket

numbers found in brackets on each guidance document. A copy of the

guidance documents and comments received may be seen in the office

above between 9 a.m. and 4 p.m., Monday through Friday.

Dated: October 21, 1999.

Margaret M. Dotzel,

Acting Associate Commissioner for Policy.

The text of the guidances follows:

GUIDANCE FOR INDUSTRY -

REDUCING MICROBIAL FOOD SAFETY HAZARDS

FOR SPROUTED SEEDS\1\

---------------------------------------------------------------------------

\1\ This guidance has been prepared by the Office of Plant and

Dairy Foods and Beverages in the Center for Food Safety and Applied

Nutrition at the Food and Drug Administration. This guidance

represents the agency's current thinking on reducing microbial food

safety hazards for sprouted seeds. It does not create or confer any

rights for or on any person and does not operate to bind FDA or the

public. An alternative approach may be used if such approach

satisfies the requirements of the applicable statute and

regulations. Following the recommendations in this guidance will not

shield any person or any food from appropriate enforcement under the

Federal Food, Drug, and Cosmetic Act if adulterated food is

distributed in interstate commerce.

---------------------------------------------------------------------------

[Docket No. 99D-4488]

All parties involved in the production of sprouts--seed producers,

seed conditioners, and distributors, and sprout producers--should be

aware that seeds and sprouted seeds have been recognized as an

important cause of foodborne illness. The following recommendations

identify the preventive controls that the Food and Drug Administration

(FDA) believes should be taken immediately to reduce the risk of raw

sprouts serving as a vehicle for foodborne illness and ensure sprouts

are not adulterated under the food safety provisions of the Food, Drug,

and Cosmetic Act (the act). Failure to adopt effective preventive

controls can be considered insanitary conditions which may render food

injurious to health. Food produced under such conditions is adulterated

under the act (21 U.S.C. 342(a)(4)). FDA will consider enforcement

actions against any party who does not have effective preventive

controls in place, in particular, microbial testing.

These recommendations are based on the recommendations of the

National Advisory Committee on Microbiological Criteria for Foods

(NACMCF, 1999) and elaborate on Compliance Policy Guide 7120.28 (CPG

7120.28).

Seed Production: Seeds for sprout production should be grown under

good agricultural practices (GAPs) in order to minimize the likelihood

that they will contain pathogenic bacteria. For more information on

GAPs, see FDA's 1998 ``Guidance for Industry: Guide to Minimize

Microbial Food Safety Hazards for Fresh Fruits and Vegetables''. Copies

of this guidance are available on the internet (http://

www.foodsafety.gov/dms/prodguid.html) or by calling the number listed

in the references and resources at the end of this guidance.

Seed Conditioning, Storage, and Transportation: Seeds that may be

used for sprouting should be conditioned, stored, and transported in a

manner that minimizes the likelihood that the seeds will be

contaminated with pathogens. For example, seed should be stored in

closed or covered containers in a clean dry area dedicated to seed

storage. Containers should be positioned off the floor and away from

walls to reduce the possibility of contamination by rodents or other

pests and to facilitate regular monitoring for pest problems.

Sprout Production: Sprouters should implement appropriate practices

to ensure that sprouts are not produced in violation of the act which

prohibits the production of food under insanitary conditions which may

render food injurious to health (21 U.S.C. 342(a)(4)). In addition to

seed treatment and testing for pathogens (see below), sprouters should

maintain facilities and equipment in a condition that will protect

against contamination. Facilities with poor sanitation can

significantly increase the risk of contaminating product. Sprouters

should employ good

[[Page 57896]]

sanitation practices as a standard operating procedure to maintain

control throughout all stages of sprout production. Inadequate water

quality and poor health and hygienic practices can all increase the

risk of food becoming contaminated with pathogens. Sprouters may wish

to review 21 CFR Part 110 which sets forth good manufacturing practices

(GMPs) in manufacturing, packaging, or holding human food that cover

these aspects of food production.

Seed Treatment: Seeds for sprouting should be treated with one or

more treatments (such as 20,000 ppm calcium hypochlorite\2\) that have

been approved for reduction of pathogens in seeds or sprouts. Some

treatments can be applied at the sprouting facility while others will

have to be applied earlier in the seed production process. However, at

least one approved antimicrobial treatment should be applied

immediately before sprouting\3\. Sprouters should carefully follow all

label directions when mixing and using antimicrobial chemicals.

---------------------------------------------------------------------------

\2\ In 1998, the Environmental Protection Agency issued a

``section 18'' for the temporary use of 20,000 ppm calcium

hypochlorite to disinfect seed for sprouting. In the fall of 1999,

the exemption was renewed for another year. However, in order to

ensure continued availability of this treatment, registrants should

be actively pursuing a full registration under section 3 in 2000.

\3\ Antimicrobials are either pesticides chemicals or food

additives, depending on where they are used. As such their use on

seeds for sprouting must be approved by EPA or FDA. To find out what

antimicrobials have been approved by EPA or FDA for use on seeds for

sprouting, you can call 202-418-3098.

---------------------------------------------------------------------------

Testing for Pathogens: Because currently approved antimicrobials

have not been shown to be capable of eliminating all pathogens from

seed, sprout producers should conduct microbiological testing of spent

irrigation water from each production lot to ensure that contaminated

product is not distributed. Because testing for pathogens can be done

with irrigation water as early as 48 hours into what is generally a 3

to 10 day growing period, producers who plan accordingly can obtain

test results before shipping product without losing product shelf-life.

Testing, whether done by the producer or contracted out, should be done

by trained personnel, in a qualified laboratory, using validated

methods. Additional information on sample collection and microbial

testing, including how to sample and test sprouts when testing spent

irrigation water is not practicable (as may be the case with soil-grown

sprouts), can be found in a companion guidance document referenced

below.

Traceback: Traceback cannot prevent a foodborne illness outbreak

from occurring. However, being able to trace a food back to it's source

quickly can limit the public health and economic impacts of an

outbreak, if it occurs. Information gained in traceback investigations

may also help prevent future outbreaks. Sprout producers, seed

producers, conditioners and distributors should develop and implement

systems to facilitate traceback and recalls in the event of a problem.

All parties should test their systems in advance of a real problem.

References and resources:

1. Food and Drug Administration. 1982. Compliance Policy Guide

Sec. 555.750 Seeds for Sprouting Prior to Food Use, i.e., Dried Mung

Beans, Alfalfa Seeds, etc. (CPG 7120.28 ) can be viewed and printed

from the WWW at the following address http://www.fda.gov/ora/

compliance_ref/cpg/cpgfod/cpg555-750.html

2. Food and Drug Administration. 1998. Guidance for Industry--

Guide to Minimize Microbial Food Safety Hazards for Fresh Fruits and

Vegetables can be viewed and printed from the WWW at the following

address http://www.foodsafety.gov/dms/prodguid.html or may be

obtained by calling 202-401-9725.

3. Food and Drug Administration, 1999. Press Release--Consumers

Advised of Risks Associated with Raw Sprouts. P99-13. http://

www.fda.gov/bbs/topics/NEWS/NEW00684.html

4. FDA, 1999. ``Guidance for Industry: Sampling and Microbial

Testing of Spent Irrigation Water During Sprout Production'' can be

viewed and printed from the WWW at http://vm.cfsan.fda.gov

5. National Advisory Committee on Microbiological Criteria for

Foods. 1999a. Microbiological Safety Evaluations and Recommendations

on Sprouted Seeds. http://vm.cfsan.fda..gov/mow/sprouts2.html

6. National Advisory Committee on Microbiological Criteria for

Foods. 1999b. Microbiological Safety Evaluations and Recommendations

on Fresh Produce. Food Control. 10:117-143.

7. Copies of Federal regulations in the Code of Federal

Regulations (CFR) may be purchased from the U.S. Government Printing

Office or by telephone at (202) 512-1800. The CFR is also available

at local branches of U.S. Government Printing Office Bookstores.

Information on location of regional branches is available on the WWW

at the following address: http://vm.cfsan.fda.gov/lrd/ob-reg.html

8. Sections of the CFR, such as 21 CFR Part 110 Current Good

Manufacturing Practices in Manufacturing, Packing, or Holding Human

Food, can be viewed and printed from the WWW at the following

address: http://www.access.gpo.gov/nara/cfr/index.html.

Appendix 2--Guidance for Industry: Sampling and Microbial Testing of

Spent Irrigation Water During Sprout Production

GUIDANCE FOR INDUSTRY -

SAMPLING AND MICROBIAL TESTING OF SPENT IRRIGATION WATER

DURING SPROUT PRODUCTION\4\

---------------------------------------------------------------------------

\4\ This guidance has been prepared by the Office of Plant and

Dairy Foods and Beverages in the Center for Food Safety and Applied

Nutrition at the Food and Drug Administration. This guidance

represents the agency's current thinking on reducing microbial food

safety hazards for sprouted seeds. It does not create or confer any

rights for or on any person and does not operate to bind FDA or the

public. An alternative approach may be used if such approach

satisfies the requirements of the applicable statute and

regulations. Following the recommendations in this guidance will not

shield any person or any food from appropriate enforcement under the

Federal Food, Drug, and Cosmetic Act if adulterated food is

distributed in interstate commerce.

---------------------------------------------------------------------------

[Docket No. 99D-4489]

Introduction

Raw sprouts have been associated with at least eleven foodborne

illness outbreaks since 1995. FDA and other public health officials are

working with industry to identify and implement production practices

that will assure that seed and sprouted seed are produced under safe

conditions. While these efforts have improved food safety awareness

within the industry and have led to a significantly better

understanding of the microbial ecology of sprout-associated foodborne

illness, not all industry segments have been reached and outbreaks

continue to occur. Consequently, FDA released a guidance document,

entitled ``Guidance for Industry: Reducing Microbial Food Safety

Hazards for Sprouted Seed'' (the ``sprout guidance''). The sprout

guidance identifies a number of areas, from the farm to the sprout

facility, where FDA believes immediate steps should be taken to reduce

the risk of sprouts serving as a vehicle for foodborne illness and to

ensure that sprouts are not adulterated under the Food, Drug, and

Cosmetic Act (the act). Specific recommendations in the sprout guidance

include: development and implementation of good agricultural practices

and good manufacturing practices in the production and handling of

seeds and sprouts, seed disinfection treatments, and microbial testing

before product enters the food supply.

The agency will closely monitor the safety of sprouts and the

adoption of enhanced prevention practices as set out in the sprout

guidance. FDA plans to send investigators to sprouting facilities to

test water used to grow sprouts (i.e., spent irrigation water) and

assess the adoption of preventive controls. Failure to adopt effective

preventive controls can be considered insanitary conditions which may

render food injurious to

[[Page 57897]]

health. Food produced under such conditions is adulterated under the

act (21 U.S.C. 342(a)(4)). FDA will consider enforcement actions

against any party who does not have effective preventive controls in

place, in particular, effective microbial testing.

This guidance document, ``Sampling and Microbial Testing of Spent

Irrigation Water During Sprout Production,'' is intended to assist

sprouters in implementing one of the principal recommendations in the

broader sprout guidance, i.e., that producers test spent irrigation

water for two pathogens (Salmonella and Escherichia coli O157:H7)

before product enters commerce. Instructions are also provided for the

sampling and testing of sprouts for those instances when it is not

possible to test spent irrigation water. However, for the reasons

discussed below, sprouts should not be tested in lieu of irrigation

water.

Why Test

Salmonella and Escherichia coli O157:H7 have been the major causes

of sprout-associated illness outbreaks. Seeds are the likely source of

contamination in most of these outbreaks. Routine use of approved seed

disinfection treatments (such as 20,000 parts per million of calcium

hypochlorite in water) is likely to reduce the level of contamination

if pathogens are present in or on seeds and, in turn, reduce the risk

of foodborne illness from the consumption of sprouted seed. However,

current approved treatments cannot guarantee total elimination of

pathogens. The same conditions that encourage germination and growth of

seeds (e.g., temperature, available moisture, and nutrients), also

encourage the growth of bacterial pathogens. Even if only a few

pathogens survive a seed disinfection treatment, they can grow to high

levels during sprouting and contaminate the entire batch. Therefore,

seed disinfection treatments should be combined with microbial testing

to ensure that pathogens are not present before sprouts enter the food

supply.

As additional food safety controls are identified and implemented,

the current recommendation to test irrigation water from every batch of

sprouts produced may be changed, e.g., to periodic microbial testing as

a tool for validating the effectiveness of food safety systems.

Who Should Perform The Tests

Sample collection

Sample collection should be done by personnel that have been

trained to collect representative samples aseptically. Obviously,

sample collection should be done on site, either by employees or by

contract personnel. Aseptic sampling procedures are described below.

Testing

FDA recommends that all testing for pathogens be conducted in an

external, qualified, independent laboratory that should meet several

key criteria. First, the lab should be physically separated from the

food production facility to prevent cross-contamination from test

materials. This is especially important where the materials used in the

enrichment step required before testing and the positive controls

(described below) can contain pathogens and if not properly handled may

contaminate sprouts.

Second, the laboratory should be staffed by personnel with training

and experience in analytical microbiology techniques to ensure that

tests are performed correctly and that all appropriate safety

precautions, including appropriate waste disposal, are followed. Third,

the laboratory should have appropriate resources and a demonstrable

quality management system.

If testing is done by the sprouter, then the laboratory facilities,

personnel, and management system should also meet all these criteria to

ensure that testing is reliable and does not create food safety

hazards.

Why Sample Irrigation Water

Procedures are provided for testing spent irrigation water and

sprouts. Although each has advantages and disadvantages, FDA is

recommending testing spent irrigation water.

Spent irrigation water that has flowed over and through sprouts is

a good indicator of the types of microorganisms in the sprouts

themselves and the microflora in spent irrigation water is fairly

uniform. Thus sampling procedures for spent irrigation wate are

relatively simple. Furthermore, water can be used directly in the test

procedures described here. The only potential disadvantage of testing

spent irrigation water is that the level of microorganisms recovered in

irrigation water is about 1 log less than the level in sprouts. If

pathogens are present in sprouts at very low levels, it is possible

that they might be missed in water but recovered in sprouts.

Testing the sprouts themselves has several significant

disadvantages. First, multiple sprout samples must be taken from

different locations in the drum or trays to ensure that the sample

collected is representative of the batch. Furthermore, additional

preparation (e.g., selecting representative subsamples for analyses,

blending or stomaching, and allowing sprout particles to settle out) is

required when testing sprouts. Each additional step in any procedure

(sampling or testing) introduces a possibility for error.

Consequently, sprouts should not be tested in place of irrigation

water unless production methods make it impossible to test spent

irrigation water. For example, spent irrigation water may not be

available when sprouts are grown in soil. [Note: The recommendation to

test irrigation water does not preclude adding the testing of sprouts

(either sprouts collected during production or finished product), to a

food safety plan that includes testing irrigation water.] Sampling and

testing steps specific to sprouts are given in italics and may be

disregarded when testing spent irrigation water.

Sampling Plan

Sprouters should have a sampling plan in place to ensure the

consistent collection of samples in an appropriate manner. The

following factors should be considered in determining when and how to

sample.

When to Sample

Pathogens are most likely to be present at detectable levels at or

after 48 hours from the start of the sprouting process. Levels will not

necessarily increase after 48 hours and may decline slightly. Thus,

collecting samples for testing can be done as early as 48 hours after

the start of sprouting. If seeds are presoaked (e.g., soaked in water

for a short time and then transferred to growing units for sprouting),

presoak time should be included in the 48 hour minimum.

If you are using rapid test kits, samples may be collected as late

as 48 hours prior to shipping and still provide an opportunity for the

sprouter to obtain test results before product enters the food supply.

However, early results will allow a sprouter to take corrective actions

sooner, minimizing the potential for a contaminated batch of sprouts to

contaminate other production batches. Earlier testing (i.e., 48 hours

after the start of sprouting) will also minimize the time and resources

spent on a batch of sprouts if a presumptive positive is found. If a

firm's action plan includes running confirmatory tests on a presumptive

positive before discarding product, testing earlier rather than later

allows more time to run additional tests.

[[Page 57898]]

How to Sample

Aseptic procedures are critical to avoid contaminating the sample

during sample collection, storing the sample(s), and transporting the

sample(s) to the lab. Aseptic sampling procedures, as described below,

should be part of a firm's plan for sample collection.

Equipment used to collect samples should be clean and sterile.

Sampling tools and sample containers may be purchased pre-sterilized.

Alternatively, tools and containers may be sterilized at 121 deg.C

(250 deg.F) for 30 minutes in an autoclave prior to use. Heat-

resistant, dry materials may be sterilized in a dry-heat oven at 140

deg.C (284 deg.F) for 3 hours.

The type of sample containers used will depend on the type of

samples collected but may include pre-sterilized plastic bags, tubes,

cups, and flasks. Containers should be dry, leak-proof, wide mouthed,

and of a size suitable for the samples. Sample containers should be

properly labeled prior to starting sample collection.

Sample collectors should wear a clean lab coat, sterile gloves, and

a hair net to insure they do not contaminate the samples. Hands should

be washed immediately before sampling, and prior to putting on sterile

gloves. Sterile gloves should be put on in a manner that does not

contaminate the outside of the glove. Gloves should be properly

disposed of after use.

Hands should be kept away from mouth, nose, eyes, and face while

collecting samples.

Sampling instruments should be protected from contamination at all

times before and during use. Sampling instruments and samples moved

between the sampling site and the sample container, should not be

passed over the remaining pre-sterilized instruments.

The sterile sample container should be opened only sufficiently to

admit the sample, place the sample directly in the container, then

immediately closed and sealed. If collecting samples in a container

with a lid, the lid and container should be held in one hand while

collecting the sample. The lid should NOT be completely removed. (The

lid should not be held separately or placed on a counter).

The sample container should be filled no more than 3/4 full to

prevent overflow. The air from the container should not be expelled

when sealing, particularly for plastic bags. Samples or sampling

equipment should not be exposed to unfiltered air currents.

Samples should be delivered to the laboratory promptly. Perishable

material should be kept at an appropriate temperature, preferably at 0

to 4.4 deg.C (32 to 40 deg.F). Sealed coolant packs should be used to

avoid contamination from melting ice.

What to Sample and How Much to Collect

FDA recommends that a sprouter test for pathogens by collecting a

sample of spent irrigation water from each production lot or batch. For

purposes of this guidance, a production lot or batch is defined as

sprouts from a single lot of seed that were started at the same time in

a single growing unit (i.e., a single drum or rack of trays). Pooling

samples should be avoided as pooling from different production batches

may decrease the sensitivity of the tests by diluting the level of

pathogens in a contaminated sample with samples that are not

contaminated. Pooling samples from different batches also complicates

the interpretation of results. If a presumptive positive is found, the

sprouter should discard all lots represented by the pooled sample or

perform additional tests to determine which batch(s) are contaminated.

1. Sample Collection for Spent Irrigation Water

The volumes given below for spent irrigation water (or sprouts)

represent a sufficient sample size to test for both Salmonella and

Escherichia coli O157:H7.

If testing spent irrigation water, 1 liter of water (about 2 pints

or one quart) should be aseptically collected as the water leaves a

drum or trays during the irrigation cycle.

If sprouts are grown in drums, a single 1 liter sample may be

collected.

If sprouts are grown in trays, and all trays in a production lot

have a common trough for collecting spent irrigation water, a 1 liter

sample may be collected at that point. If there is no common collection

point for water from trays, it may be necessary to collect water

samples from individual trays and pool these samples. In this case, a

sampling plan should be devised to ensure collection of a sample that

is representative of the production lot. When 10 or fewer trays make up

a production lot, approximately equal volumes of water should be

collected from each of the 10 trays to make a total sample volume of 1

liter. For example, collect about 100 ml of water from each of 10 trays

to make a 1 liter sample; about 125 ml from each of 8 trays; 167 ml

from each of 6 trays, and so on. When more than 10 trays make up a

production lot, ten samples should be aseptically collected,

approximately 100 ml each from different trays. Again, samples should

be collected throughout the entire production lot (e.g., if there are

20 trays in a production lot, collect samples from every other tray in

the rack moving from top to bottom, side to side, and front to back).

Samples should be placed directly into a clean, sterile, prelabeled

container.

2. Sample Collection for Sprouts

If testing sprouts, thirty-two (32) sample units should be

aseptically collected, approximately 50 grams each, from different

locations in the drum or growing trays. The total sprout sample will be

approximately 1,600 g (about 56.48 ounces or 3.53 pounds per production

lot or batch). Sample units should be collected throughout the entire

production lot (e.g., from top to bottom, side to side, and front to

back of the drum or trays). Each 50 gram sample unit should be placed

directly into individual clean, sterile, prelabeled containers.

(Keeping the thirty-two sample units separate will make it easier for

the lab to select representative analytical units for microbial

analysis compared to pulling analytical units from a single 1,600 gram

mass of sprouts.)

Microbial Testing

Testing Procedures

The testing procedures described in this guidance are screening

tests. They were chosen to obtain results as simply and quickly as

possible (i.e., to provide answers in 48 hours or less) on the presence

or absence of two major pathogenic bacteria, i.e., Salmonella and

Escherichia coli O157:H7. Formal confirmation methods, which take

longer than 48 hours, are described in the FDA Bacteriological

Analytical Manual (published by AOAC International, Gaithersburg, MD).

The kits identified in this guidance are AOAC approved screening

tests and/or FDA has experience with their use. These are also the

tests that FDA plans to use as screening tests to monitor spent

irrigation water at sprouting facilities. If screening methods, other

than those described here are used, they should first be validated

either by formal collaborative studies or by comparative studies with

standard methods using the specific commodity in question spent

irrigation water or sprouts.

Procedures for determining the presence or absence of Escherichia

coli O157:H7 and Salmonella species using the test kits listed below

are provided at the end of this guidance. These procedures should be

performed separate from the food production

[[Page 57899]]

facility by a qualified laboratory, preferably an independent,

certified lab.

The rapid test procedures described in this guidance all involve an

enrichment step to encourage the selective growth of pathogens, if they

are present, in order to make their detection possible. These test kits

will NOT detect pathogens in irrigation water or sprouts if the

enrichment step is not performed.

In addition, seasonal or regional differences in water quality,

type of seed being sprouted, individual sprout production factors, and

variations in sampling and analytical conditions may all impact on the

effectiveness of the screening tests. Therefore, the lab should

periodically run positive controls (i.e., sprout or water samples to

which a known quantity of pathogens have been added) to ensure the

tests used are capable of detecting pathogens when they are present in

the samples being tested.

Test Kits

Escherichia coli O157:H7

1. VIP EHEC, Biocontrol, Inc., Bellview, WA., (AOAC Official method

996.09)

2. Reveal E. coli O157:H7, Neogen Corp., Lansing, MI.

Salmonella

1. Assurance Gold Salmonella EIA, (AOAC Official method

999.08)

2. Visual Immunoprecipitate (VIP) Assay for Salmonella, (AOAC

Official method # 999.09)

(Both kits are manufactured by BioControl Systems, Inc., 12822 SE

32nd Street, Bellevue, WA 98005).

General Laboratory Instructions

Prepared Media Storage

Unless noted otherwise most media can be made in advance and stored at

20-30 deg.C (68-86 deg.F) in the dark with a shelf life of at least

one month. Media should be well wrapped or contained in order to reduce

evaporation.

Equipment Sterilization

Safe and proper operation of sterilizing autoclaves requires specially

trained personnel. The sterilization time is typically 121 deg.C (250

deg.F) for 15 minutes.

Media and Equipment Decontamination

Used culture media and test kits should be decontaminated by

autoclaving before disposal. Decontamination should be performed in an

area that is totally separated from media preparation and

sterilization. Trained personnel should be used to properly

decontaminate used media.

Dividing Samples into Subsamples for Analyses

Spent Irrigation Water - A total of 1 L of spent irrigation should be

collected for analysis. Two (2) 100 ml subsamples should be analyzed

for the presence of E. coli O157:H7. Two (2) 375 ml subsamples should

be analyzed for the presence of Salmonella. Any unused portion of the

spent irrigation water should be stored under refrigeration pending

completion of the analysis.

Sprouts - Thirty-two (32) 50 g analytical units of sprouts should be

collected for analysis. Two (2) of the 50 g analytical units (25 g

subsamples from each) should be analyzed for the presence of E. coli

O157:H7 and thirty (30) of the 50 g sample units (25 g subsamples from

each) should be analyzed for the presence of Salmonella. Unused

portions of the sprout analytical units should be stored under

refrigeration pending completion of the analysis.

Sample preparation (stomaching sprouts)

The procedures in this guidance use a blender to prepare sprouts for

testing. As an alternative to blending, sprouts may be homogenized in a

Stomacher (Model 400). To use a Stomacher, place 25 grams of sprouts in

a sterile Stomacher bag, add 225 ml enrichment broth and process on

medium speed for 2 minutes.

Interpretation of Results and Subsequent Actions

Interpreting Results

Analyses should be performed in duplicate (two tests for each of

the two pathogens). When results are negative for all tests, results

are assumed to be correct. When results are positive for one or both

tests for either pathogen, the results are considered presumptive and

the grower should either:

1. Consider the presumptive positive result(s) to be true and take

immediate corrective actions, as described below, OR

2. Ask the testing laboratory to run confirmatory tests and destroy the

batch only if the confirmatory tests are also positive for the presence

of a pathogen.

In considering the second option, remember that confirmatory

testing takes extra time and will lessen the marketable shelf life of

the sprouts. (All product should be held until test results are

available.) Rapid test kits are for screening ONLY. Confirmatory

testing should be done using standard methods in the FDA

Bacteriological Analytical Manual (Edition 8, Revision A-1998).

Corrective Actions

Each facility should have a corrective action plan in place before

a positive is found so that, if one does occur, corrective actions can

be taken quickly. The following should be included in a corrective

action plan.

Seed is the likely source of contamination in sprout-associated

foodborne illness outbreaks. Further, recent outbreak investigations

have shown that a single contaminated seed lot can result in

contamination of multiple production lots of sprouts. Therefore, when a

batch of sprouts is considered to be contaminated with a pathogen, the

batch of sprouts, the seed lot used to produce the sprouts, and any

other sprout production lots that were made from the same seed lot and

that are still under control of the sprouter, should be discarded.

In addition, anything in the sprouting facility that has come into

contact with the contaminated production lot or its water (e.g., drums,

trays, bins, buckets, tool and other sprouting equipment, testing

equipment, and other possible surfaces, such as floors, drains, walls,

and tables), should be thoroughly cleaned and then sanitized to avoid

contamination of subsequent batches of sprouts. Care must be taken in

handling contaminated sprouts or water, equipment, and test materials

to avoid accidental exposure to the pathogen(s).

A) Procedure for the Escherichia coli O157:H7 Rapid Analysis of

Spent Irrigation Water or Sprouts.

I. Test Kits choose one. VIP EHEC\5\, Biocontrol, Inc.,

Bellview, WA., or Reveal E. coli O157:H7\5\, Neogen Corp.,

Lansing, MI.

---------------------------------------------------------------------------

\5\ The enrichment procedure described in this guidance for the

tests for Escherichia coli O157:H7 have been modified by FDA to

enhance the ability of the kits to detect Escherichia coli O157:H7

in spent irrigation water and sprouts.

---------------------------------------------------------------------------

II. Equipment and Materials

1. 1 Mechanical blender (capable of 10,000 to 12,000 rpm) or Stomacher

Model 400 (with required stomacher bags)

2. Sterile blender jars, with cover, resistant to autoclaving for 60

min at 121 deg.C

3. 1 Balance, with weights (2000 g capacity, sensitivity of 0.1 g)

4. 1 L Erlenmeyer flask

5. 2 Sterile graduated pipettes, 1.0 and 10.0 ml and pipette aids

6. Sterile instruments for use in taking and handling of samples (such

as knives, tongs, scissors, spoons, etc.)

7. Sterile culture tubes, 16 x 150mm or 20 x 150mm

8. Incubator/shaker platform, 35 + 1 deg.C

9. pH meter or test strips

10. Fisher or Bunsen burner

11. Magnetic stirrer and stir bars

[[Page 57900]]

12. Sterile syringes

13. Sterile 0.2 m filters

14. Distilled water

III. Ingredients

1. Peptone

2. NaCl

3. Na2HPO4

4. KH2PO4

5. Casamino acid

6. Yeast extract

7. Lactose

8. Acriflavin (antibiotic)

9. Cefsulodin (antibiotic)

10. Vancomycin (antibiotic)

Preparation of antibiotic stock solutions

Prepare a stock solution of each antibiotic (acriflavin, cefsulodin,

and vancomycin) by dissolving 1000 mg of each antibiotic in a separate

tube containing 10.0 ml of distilled water. Filter-sterilize the

solution using a 0.2 m filter and syringe. The stock solution may be

stored for several months in foil wrapped tubes at 4 C (39.2 C).

Prepare the modified Buffered Peptone Water as described below,

autoclave, cool, add antibiotic supplements. Instructions for sprouts

are given in italics.

Modified Buffered Peptone Water (mBPW)

Step 1. To make 1000 ml of mBPW, mix the following constituents into

distilled water, stirring to dissolve. For spent irrigation water,

prepare double strength (2X) mBPW, as follows: (If testing sprouts, use

single strength enrichment broth base.)

------------------------------------------------------------------------

Modified Buffered Peptone Water (mBPW)

-------------------------------------------------------------------------

Double

strength (2X) Single

(For use with strength (1X)

Ingredient spent (For use with

irrigation sprouts)

water)

------------------------------------------------------------------------

Peptone 20.0 g 10.0 g

NaCl 10.0 g 5.0 g

Na2HPO4 7.2 g 3.6 g

KH2PO4 3.0 g 1.5 g

Casamino acid 10.0 g 5.0 g

Yeast extract 12.0 g 6.0 g

Lactose 20.0 g 10.0 g

Distilled water* 1000 ml 1000 ml

------------------------------------------------------------------------

*pH 7.2 0.2 (Test pH of distilled water BEFORE adding the

ingredients above. If necessary, pH may be adjusted with 1N HCl or 1N

NaOH.

Step 2. Sterilize mBPW by autoclaving at 121 deg.C (250 deg.F) for 15

minutes. Remove from autoclave and allow to cool until cool to the

touch.

Step 3. Once the medium is cooled and immediately prior to the addition

of a subsample, add the following filter-sterilized antibiotics to 1000

ml of medium. For spent irrigation water, add the quantity of

antibiotics listed in the column labeled double strength to the double

strength (2X) mBPW. (If testing sprouts, add the quantity of

antibiotics listed in the column labeled single strength to the single

strength mBPW.)

----------------------------------------------------------------------------------------------------------------

Antibiotic supplements for mBPW

-----------------------------------------------------------------------------------------------------------------

Double

strength (2X)

Antibiotic Stock (For use with

Solution spent Single strength (1X) (For use with sprouts)

irrigation

water)

----------------------------------------------------------------------------------------------------------------

Acriflavin (A) 0.2 ml 0.1 ml

Cefsulodin (C) 0.2 ml 0.1 ml

Vancomycin (V) 0.16 ml 0.08 ml

----------------------------------------------------------------------------------------------------------------

IV. Testing - Perform analysis in duplicate: For microbial testing,

duplicate sub-samples (analytical units) need to be removed from

the sample and placed in enrichment broth. Enrichment broth

containing sub-samples are allowed to incubate for a period of

time, and a small quantity of the enrichment broth/sample is

applied to the test kit device. Specific directions follow:

Step 4.

Water: Two (2) 100 ml subsamples of spent irrigation will be analyzed.

From the 1000 ml sample of spent sprout irrigation water, aseptically

transfer 100 ml of sample into a sterile 1L flask containing 100 ml of

2X mBPW+ACV. Repeat with second subsample.

Sprouts: Two (2) 50 g analytical units of sprouts will be analyzed.

From two of the thirty-two 50 g analytical units collected, aseptically

remove and weigh out a 25g subsample of sprouts. Transfer each of the

25 gram subsamples of sprouts into separate sterile blender jars or

sterile stomacher bags. Add 225 ml of single strength enrichment broth

with added antibiotic supplements (1X mBPW+ACV) and blend at 10,000 to

12,000 rpm until homogenized (at least 60 seconds) or stomach for 2

minutes on medium setting in a Stomacher Model 400. Transfer sprout

homogenate to a 1L Erlenmeyer flask.

[[Page 57901]]

Step 5. Incubate the enrichment broth/sample mixtures overnight at

37 deg.C (98.6 deg.F) with shaking at 140 RPM.

Step 6. Test each enrichment broth sample for the presence of E.

coli O157:H7, using either the VIP EHEC device or the Reveal E.

coli O157:H7 device. Use 0.1 ml from the inoculated and incubated

mBPW +ACV to inoculate VIP or 0.12 ml for the Reveal. Follow the

manufacturers instructions for the inoculation of test kits.

Step 7. Observe test results within 10 minutes to avoid possible

fading of bands which could lead to false negative results. A band

in both the test and control chambers is a positive test for

contamination. A band in only the control chamber is a negative

test. If a band does not appear in the control chamber, the test

was not done correctly and must be repeated.

B) Procedure for the Salmonella Rapid Analysis of Spent Irrigation

Water (or Sprouts)

I. Test kits choose one

Assurance Gold Salmonella EIA, or

Visual Immunoprecipitate (VIP) Assay for Salmonella

Both are manufactured by BioControl Systems, Inc., (12822 SE 32nd

Street, Bellevue, WA 98005). For purposes of pre-enrichment and

selective enrichment, these test kits provide different instructions

for each of three types of foods: (a) processed foods, (b) dried powder

processed foods, and (c) raw foods. For the analysis of sprouts and

spent irrigation water, use the pre-enrichment/selective enrichment

procedures described for (c) raw foods.

II. Equipment and materials1. Blender and sterile blender jars OR

Stomacher Model 400 with appropriate stomacher bags.

2. Sterile, 16 oz (500 ml) wide-mouth, screw-cap jars, sterile 500 ml

Erlenmeyer flasks, sterile 250 ml beakers, sterile glass or paper

funnels of appropriate size, and, optionally, containers of appropriate

capacity to accommodate composited samples

3. Balance, with weights; (2000 g capacity, sensitivity of 0.1 g)

4. Balance, with weights; (120 g capacity, sensitivity of 5 mg)

5. Incubator, 35 deg.C (95 deg.F)

6. Refrigerated incubator or laboratory refrigerator, 4 + 1 deg.C (39

+ 1 deg.F)

7. Water bath, 42 + 0.2 deg.C (107.6 + 0.2 deg.F)

8. Sterile spoons or other appropriate instruments for transferring

food samples

9. Sterile culture dishes, size 15 x 100 mm, glass or plastic

10. Sterile pipettes, 1 ml, with 0.01 ml graduations; 5 ml with 0.1 ml

graduations and 10 ml with 0.1 ml graduations and pipette aids

11. Inoculating needle and inoculating loop (about 3 mm id or 10 l),

nichrome, platinum-iridium, chromel wire, or sterile plastic

12. Sterile test or culture tubes, sizes 16 x 150 mm and 20 x 150 mm

13. Test or culture tube racks

14. Vortex mixer

15. Sterile shears, large scissors, scalpel, and forceps

16. Fisher or Bunsen burner

17. pH test paper (pH range 6-8) with maximum graduations of 0.4 pH

units per color change

18. Sterile syringe

19. Sterile 0.2 m filters

III. Media and reagents

For preparation of media and reagents, refer to sections 967.25 to

967.28 in Official Methods of Analysis (published by AOAC

International, Gaithersburg, MD USA). Designations within parentheses

refer to Appendix 3, Media and Reagents, of the Bacteriological

Analytical Manual (BAM), Edition 8, Revision A ( also published by AOAC

International).

1. Buffered peptone water (commercially available-Oxoid, BBL, or Difco)

2. Buffered peptone water + novobiocin

3. Tetrathionate (TT) broth (M145)

4. Rappaport-Vassiliadis (RV) medium (M132)

5. Trypticase soy broth (commercially available)

6. Trypticase soy broth + novobiocin

7. Trypticase soy broth + 2, 4 dinitrophenol + novobiocin

8. 1 N Sodium hydroxide solution (NaOH) (R73)

9. 1 N Hydrochloric acid (HCl) (R36)

10. Novobiocin solution, 0.1%

11. Sterile distilled water

Buffered peptone water (Number 1.), Buffered peptone water with

novobiocin (Number 2), Trypticase soy broth with novobiocin (Number 6)

and Trypticase soy broth with 2,4 dinitrophenol and novobiocin (Number

7), are not included in the BAM. Their preparation is described below.

1. Buffered Peptone Water (BPW)

Dissolve 20 grams of commercially available buffered peptone water

medium in 1 liter distilled water. Mix thoroughly. Dispense 225 ml

portions into 500 ml Erlenmeyer flasks. After autoclaving for 15 min at

121 deg.C, and just before use, aseptically adjust volume to 225 ml

with sterile distilled water. Adjust pH, if necessary, to 7.2 + 0.2

with sterile 1 N NaOH or 1 N HCl.

2. Buffered Peptone Water + novobiocin (BPW + n)

Immediately prior to the addition of a 25 g subsample, add 4 ml of 0.1%

novobiocin solution to each 225 ml volume of buffered peptone water.

6. Trypticase soy broth + novobiocin (TSB+n)

Suspend 30 g of commercial available trypticase soy broth medium in 1 L

of distilled water. Mix thoroughly. Warm gently on a temperature

controlled hot plate until the medium is dissolved. Dispense in 10 ml

aliquots in 20 x 150 mm tubes and autoclave 15 min. at 121 deg.C.

Just prior to sample addition, add 0.1 ml of 0.1% novobiocin solution

to each tube containing 10 ml of Trypticase soy broth.

7. Trypticase soy broth + 2, 4 dinitrophenol + novobiocin (TSB+DNP+n)

Suspend 30 g of commercial available trypticase soy broth medium and

0.1 g of 2, 4 dinitrophenol in 1 L of distilled water. Mix thoroughly.

Warm gently on a temperature controlled hot plate until the medium is

dissolved. Dispense in 10 ml aliquots in 20 x 150 mm tubes and

autoclave 15 min. at 121 deg.C (250 deg.F).

Just prior to sample addition, add 0.1 ml of 0.1% novobiocin solution

to each tube containing 10 ml of Trypticase soy broth + 2, 4

dinitriphenol.

9. Novobiocin solution, 0.1%

Novobiocin, sodium salt 0.1 g

Distilled water 100 ml

Dissolve novobiocin in distilled water. Do not autoclave. Sterilize by

filtering through a 0.2 m filter. Store solution at 4 deg.C (39.2

deg.F), protected from light (e.g. wrap container in aluminum foil).

Solution can be stored for one week.

IV.Testing

A. Irrigation water-From the 1 L spent irrigation water sample, two (2)

375 ml subsamples will be analyzed for the presence of Salmonella.

1. Aseptically transfer a 375 ml subsample directly to a 6 L Erlenmeyer

flask containing 3,375 ml BPW + n. Swirl to mix thoroughly. Repeat

procedure with second 375 ml subsample of spent irrigation water.

2. Allow flasks to stand for 60 min at room temperature. Mix well and

determine pH with test paper. Adjust pH, if necessary, to 6.8 + 0.2

with sterile 1 N NaOH or 1 N HCL.

3. Incubate flasks without shaking for 18-26 hours at 35-37 deg.C (95-

98.6 deg.F). Each flask is considered to contain pre-enrichment broth.

[[Page 57902]]

4a. If using the Assurance Gold Salmonella Enzyme Immunoassay, transfer

0.1 ml pre-enrichment broth to 10 ml RV medium and transfer another 1.0

ml of pre-enrichment broth to 10 ml TT broth. Incubate in a water bath

5-8 hours at 42 deg.C (107.6 deg.F). Incubation of the RV medium and

TT broth in the water bath is termed the selective enrichment process.

Following selective enrichment, transfer and combine 1.0 ml TT broth

and 0.5 ml RV medium into a single tube containing 10 ml of prewarmed

[42 deg.C (107.6 deg.F)] TSB + n broth. Incubate in a water bath 16-

20 hours at 42 deg.C (107.6 deg.F). Continue as described in this

kit's instructions for (c) raw foods.

4b. If using the VIP Assay for Salmonella, transfer 0.1 ml pre-

enrichment broth to 10 ml RV medium and transfer another 1.0 ml of pre-

enrichment broth to 10 ml TT broth. Incubate in a water bath 18-24

hours at 42 deg.C. Incubation of the RV medium and TT broth in the

water bath is termed the selective enrichment process. Following

selective enrichment, transfer and combine 0.5 ml of TT broth and 0.5

ml RV medium into a single tube containing 10 ml prewarmed [42 deg.C

(107.6 deg.F)] TSB+DNP+n broth. Incubate in a water bath 5-8 hours at

42 deg.C (107.6 deg.F). Continue as described in this kit's

instructions for (c) raw foods.

B. Sprouts - Thirty 50 g analytical units of sprouts were collected for

Salmonella analysis. Aseptically weigh out a 25 g subsample from each

analytical unit and transfer each subsample to a sterile blending jar

(or stomacher bag). Add 225 ml buffered peptone water plus novobiocin

(BPW + n). Blend the 25 g sprout subsample with 225 ml BPW + n for 2

min. Repeat procedure for remaining twenty-nine analytical units.

1. The thirty 25 g sprout subsamples may be analyzed by either of the

following two options:

Option A:

Each 25 g/225 ml blended sprout homogenate is poured into a 500 ml

Erlenmeyer flask, or equivalent container, and analyzed individually.

Option B:

Fifteen of the thirty 25 g/225 ml blended sprout homogenates are

poured into a 6 L Erlenmeyer flask, and analyzed collectively. Repeat

with the remaining 15 blended sprout homogenates . Thus, each sample

consists of two 375-g composites .