A three-day food history and investigation observation should be used to guide the selection of appropriate foods for analysis. An investigation should be conducted before submitting samples to the lab for analysis. The following information must be provided with the samples at the time of submission:

• Symptoms
• Incubation period
• Duration of illness
• Physician's diagnosis
• Results of any clinical tests or cultures

Specimen Collection and Shipment

After determining the appropriate food specimen to submit, aseptically collect approximately 200 grams of a solid product or about 100 ml of a liquid. Collection should be in a sterile whirl-pak plastic bag or sterile urine collection cup. The laboratory does not provide sterile collection containers for food collection.

All samples must be kept cold (<10°C) during transit to the laboratory. Samples that are shipped should be placed in a leak-proof shipping container, preferably a Styrofoam container, packed with sealed cold packs (i.e. blue ice packs). Samples that are hand delivered on wet ice should be protected from cross contamination as the ice melts during transit.

A properly completed laboratory submission form must accompany each individual sample. Each sample must be identified by a number that corresponds to the same identification number written in the submitter sample information on the submission form. The Bacterial Food Analysis Submittal/Report Form may be picked up at the Receiving Department at the State Health Laboratory or requested by calling (602) 542-1190.

Laboratory Analysis

Quality control samples are tested for aerobic plate count, total coliforms, fecal coliforms and E. coli.

Pathogen isolation and identification is available for foods implicated in food borne illness outbreaks. Tests available include, but are not limited to, the following:

• Staphlococcus aureus plate count
• Bacillus cerues plate count
• Clostridium perfringens plate count
• Yeast and mold count
• Salmonella isolation
• Campylobacter isolation
• E. coli 0157:H7 isolation
• Filth analysis
• Foreign object identifications
• Container analysis

Food samples are analyzed according to methods specified in the Bacteriological Analytical Manual (FDA BAM) or by methods specified by the National Centers for Disease Control (CDC). When appropriate, rapid analytical test kits are used to screen samples for pathogens to provide quicker test results during food outbreak investigations or emergencies. The rapid test results usually take only 1 to 2 days. However, positive results of these tests are only presumptive and conventional tests need to be done to confirm these results.

Results and Reports

Preliminary results are usually available within 48 to 72 hours after processing has begun. Confirmatory test results are usually available within 48 hours to ten days depending on the test organism. Please contact the Environmental Microbiology Department at (602) 542-6130 at any time for updates on the progress of the testing. Generally, final reports are mailed out three to eleven days after initial processing begins.

Interpretation of lab results is the responsibility of the submitter. The laboratory will consult with the submitter, if requested. No legal food standards are available on most products, so care and common sense are needed in the interpretation of lab data. Use your experience and comparisons to evaluate the results.