Why is it important to test Pet Food for microbiology?

Pet Food microbiologyThe pet food industry is nearly a $22.2 Billion dollar a year industry and projected to almost double by the year 2017.  Nearly 101 million homes have at least one pet in the household, and there are nearly 170 million cats and dogs owned in the United States alone.  New trends in pet food are emerging as consumers want to give their pets the freshest food possible and make sure that it is healthier for them as well.  In the past few years there have been multiple outbreaks related to pet food affecting the health of both pets and humans.  Most people associate Salmonella as a bacterium linked to food borne illness in people food, but in recent years there have been quite a few outbreaks of Salmonella in pet food that has also affected humans.  The most concerning aspect is that it primarily caused illness in small children.

Several recalls of pet food due to Salmonella happened in the recent past as shown in the examples that follows. On February 5, 2014 – Pro-Pet LLC, has initiated a voluntary recall of a limited number of Dry Dog and Cat Foods for possible Salmonella contamination. A single field test indicated products manufactured during a two-day period, on a single production line might have the potential for Salmonella contamination1.  On January 25, 2014 – PMI Nutrition, LLC (PMI), has initiated a voluntary recall of its 20 lb. bags of Red Flannel® Cat Formula cat food for possible Salmonella contamination2. On November 4, 2013 – Bailey’s Choice LLC, had recalled its 5 oz. packages of chicken treats because they have the potential to be contaminated with Salmonella, an organism which can cause serious and sometimes fatal infections in young children, frail or elderly people, and others with weakened immune systems3.

The CDC also added an information page on keeping people and pet healthy and safe from Salmonella4.  There was also a pet food recall based on an aflatoxin contamination.  The Center for Disease Control (CDC) categorizes aflatoxin as a naturally occurring fungal toxin that contaminates maize and other types of crops during production, harvest storage or processing5.  The aflatoxin outbreak was linked to the death of over a hundred pets.  In the past year Kroger stores recalled a wide variety of pet foods due to a possible contamination caused by aflatoxin4.

Microbiology Testing of Pet Foods

Why test for indicator organisms? It is more effective to test for indicator organisms rather than to test for pathogens such as Salmonella.  Indicator organisms are used to measure potential fecal contamination of environmental samples. The presence of coliform bacteria, such as E. coli, is a common indicator of fecal contamination. Indicator organisms are typically used to demonstrate the potential presence or absence of groups of pathogens. The use of indicators is attractive because it reduces the complexity and cost of analyzing. Indicator bacteria are selected for the following reasons:

1) They are initially abundant in the matrix to be assayed.

2) A relatively rapid, accurate, and cost effective analytical method for enumerating the indicator exists or can be readily developed.

3) A reasonably strong correlation exists between the presence/absence of the indicator and a particular pathogen or group of pathogens. The strength of the correlation will determine the effectiveness and accuracy of the indicator as a measure of pathogen occurrence.

4) Indicator organisms can be used to pet food manufacturing to cleanliness and sanitary issues within the facility.

Assays Performed on pet foods: in pet food, testing is conducted for Enterobacteriaceae or fecal coliform as indicator of fecal contamination and yeast and mold as indicators for general quality and aflaxoins.

What are the advantages of the BioLumix system?

The system serves, as a platform to perform all required assays- using the BioLumix system will allow the pet food manufacturers to test their products not only for Salmonella and yeast/molds, but also for indicator organisms such as coliforms, fecal coliforms, Enterobacteriaceae and more.

Saving time- The BioLumix system can save time when testing pet food products for Yeast and Mold, instead of taking five days using traditional plates, the BioLumix system will give the same results in under 48 hours.  This can help the manufacturers to avoid a potential aflatoxin contamination by knowing if their product contains any amount of mold.

Economical cost of assays: Instead of running an MPN assay, which will require up to 5 days of testing as well as 9 tubes of LTB and up to 9 tubes of EC Media to wait for confirmation of a positive fecal coliform, the BioLumix system requires less than 24 hours and a single vial.  Finally, the last confirmation step is to streak the positive EC Media to L-EMB agar plates; the BioLumix system instead requires one test vial and 1ml of the sample in order to detect a level as low at <10 cfu/gram, and can give results in under 24 hours.  Similarly, the Enterobacteriaceae test in BioLumix requires one vial instead of multiple MPN tubes required by the European method.

Screening Products: BioLumix Rapid Microbiology Testing can also be helpful in screening products to determine what the next steps are.  Some manufacturers sample the product from the line and test for total aerobic count. If the level is below a certain number, then the product can be sent out to the market, if it is above the specification level then it has to go through a special sterilization procedure which costs more money as well as a delay in the product reaching the customer.

BioLumix Pet Food Study

BioLumix originally conducted a study of different store bought pet foods, ranging from dry dog food samples to wet (oil based) samples.  All samples matched the results for Yeast/Mold, Enterobacteriaceae, Total Aerobic Count, E. coli and fecal coliforms when comparing between the BioLumix System and traditional plating methods.  The products were processed and tested using FDA-BAM methods7.

Total Aerobic Count: There was 100% agreement between the two methods for all samples tested. Fourteen samples were below the specified level by both methods.  One sample was above the specified level by both methods.  One sample was inoculated to show the ability of the system to detect positive samples.

Yeast and Mold Count: There was 100% agreement between the two methods. Fifteen samples were below the specified level by both methods and two samples were above the specified level by both methods. One samples was inoculated with yeast or mold to show the ability of the system to detect positive samples.

Enterobacteriaceae: There was 100% agreement between the two methods. Thirteen samples were below the specified level by both methods and two samples were above the specified level by both methods.

E. coli: Fifteen products were tested for E. coli at a level of Absence in 10 grams.  There was 100% agreement between the two methods. Fifteen samples were below the specified level by both methods. One sample was inoculated with E. coli and were detected as containing E. coli by both methods

Salmonella: Ten products were tested for Salmonella at a level of Absence in 25 grams.  There was 100% agreement between the two methods. Ten samples were below the specified level by both methods after a confirmation step. One sample was inoculated with Salmonella and was detected as containing Salmonella.

BioLumix has also conducted a study using fresh pet food, which is an emerging product in the marketplace.  The study yielded similar results as the initial BioLumix study, except Lactic Acid Bacteria was also tested.

The BioLumix System showed a high correlation between the instrument results and the BAM methodology.  It simplified the microbiological testing, offers a significant reduction in time to obtain results and reduces hands-on labor due to its automation and simplicity of use.  The time to results for bacteria was hours rather than days while yeast and mold required only 48 hours instead of 5 days.

  1. http://www.fda.gov/Safety/Recalls/ucm384876.htm
  2. http://www.fda.gov/Safety/Recalls/ucm374043.htm
  3. http://www.cdc.gov/features/salmonelladrypetfood/
  4. http://www.cdc.gov/features/salmonelladrypetfood/
  5. http://www.cdc.gov/nceh/hsb/aflatoxin/
  6. http://www.prnewswire.com/news-releases/kroger-recalls-pet-foods-due-to-possible-health-risk-112125284.htm
  7. http://www.fda.gov/food/foodscienceresearch/laboratorymethods/ucm2006949.htm

Confirmation Testing of Presumptive Positive Assays Using the BioLumix System

In Microbiology, the initial test result using selective or differential media is called Presumptive Test. Most presumptive tests require confirmation. Confirmation can be accomplished using specific reagents and materials. However, due to the critical importance of testing for pathogens and/or objectionable organisms as contaminants; it may be necessary to perform identification of any organisms isolated from samples. Identification measures microorganisms to the species level.

Initial Testing

For testing of any sample for the presence of microorganisms it is critical to perform a measure of total organism counts (viable organisms). BioLumix provides testing for both Total Aerobic Counts (Bacteria) and for Total Yeast and Mold Counts (Fungi). The BioLumix system in this regard mimics testing for both bacteria and fungi using USP or BAM plate methodology. In these initial tests for total counts there isn’t any discrimination of objectionable organisms from common organisms and common flora. Objectionable organisms for Nutraceutical Samples as an example may include E coli, Staphylococcus aureus, Salmonella or Pseudomonas aeruginosa.

Use of Selective Media

For most samples, it will be necessary to test for at least some objectionable organisms. In order to perform tests for each specific objectionable organism it is necessary to use selective media specifically designed to select for the target organisms. For example, for E coli testing, it is necessary to use selective media that contains both inhibitors that prevent the growth of non-E coli organisms and substrates that can utilized by E coli and not by most other microorganisms. BioLumix make use of such a media, referred to as the EC vial.

Confirmation Test

Unique confirmation tests that can be performed directly from the vials are described for the various objectionable organisms.

E. Coli- Indole Test

For samples that grow and detect in the BioLumix system, a series of Confirmation Tests can be utilized to begin the process of understanding whether the organism(s) are genuine E coli or not. For E coli testing a common initial confirmation test is the Indole Test using the Kovacs reagent. The Indole Test measures the presence of any indole in the growth media as a by-product of tryptophan metabolism by E. coli. Figure 1 depicts a negative (yellow ring) and positive Kovacs Reaction (Red ring) at the top of the media in the test vial.

Staphylococcus aureus – Coagulase Test

The BioLumix vial for testing for the presence of Staphylococcus aureus contains inhibitors of non-Staphylococcus organisms and substrates, such as mannitol as the sole carbon source used by S aureus. If growth is found in the BioLumix STA vial, the analyst can begin to confirm the presence or absence of S. aureus, directly from the vial, using the classic coagulase tests. The coagulase test that has been used for decades uses a known antisera specific for S. aureus epitopes. When S aureus is present, the antiserum reacts with the specific epitopes and forms a lattice of antibody-antigen, and the material coagulates within hours. Figure 2 illustrates the coagulase positive (upper tube) and negative (lower tube) reaction.

Pseudomonas aeruginosa- Oxidase Test

The BioLumix vial for testing for the presence or absence of Pseudomonas aeruginosa contains inhibitors such as Centrimide to prevent the growth of non-pseudomonads and substrates for use by P. aeruginosa. If growth is found in the BioLumix PSE vial, the analyst can begin to confirm the presence or absence of P. aeruginosa using the classic oxidase test. When P. aeruginosa is present, the oxidase test strip reacts with the centrifuged precipitate material (bacterium) and yields a rapid dark blue reaction. This reaction is based on the presence of certain cytochrome oxidase that are found intracellularly in the P. aeruginosa.Figure 3 illustrates the positive oxidase color test ( + ) from the negative reaction ( – ).

Salmonella- Immunoassay Strip

The BioLumix vial for testing for the presence of Salmonella contains inhibitors of non-salmonella bacteria and substrates utilized by Salmonella. If growth is found in the BioLumix SAL vial; the analyst can begin to confirm the presence of absence of Salmonella using commercially available test kits that typically make use of Immunological reactive endpoints. One such kit is shown in the cartoon (Figure 4) and depicts immuno-reactive bands on a test strip.

Identification

Any negative confirmation assay indicates that the target organism is absent and the result is negative. However, in the rare occasions that the vial shows growth and the confirmation assay is positive, it does not necessarily mean that an objectionable organism is present. In these situations further identification of the growing organism might be required. The growing organism could be isolated on selective or non-selective medium and identified by any appropriate identification system.

Rapid Microbiological Testing of Capsules, Softgels and Pills Encapsulation of Pharmaceuticals

Pharmaceutical products may be encapsulated in a relatively stable shell for oral consumption.  These shells are called capsules and can either be hard-shelled or soft-shelled.  Hard-shell capsules are commonly filled with dry powdered ingredients, pellets, or granules.  Soft-shell capsules (softgels) are made from gelatin and primarily contain oils or active ingredients that are dissolved or suspended in oil.  Both hard and soft-shell capsules may contain colorants, dyes, opaquing, dispersing, or hardening agents, and preservatives.  Tablets are solid doses of medicinal substances and may be soluble effervescent, chewable, molded, or compressed.

Traditional methods for testing

Plate count methodology as described in USP <61> is regularly used to test capsules and tablets.  Using this methodology, it takes two days for Aerobic Count results, and five days for Yeast and Mold results.  When testing for objectionable organisms, it may take several days using selective broths or agars to determine the absence or presence of these bacteria.   The colors of the shells and the products and the viscosity of the 1:10 dilution sometimes interfere with the reading of the plates.

Rapid Detection with the BioLumix System

The BioLumix System simplifies testing, expedites time to results, reduces the testing cost and accelerates product release while providing better control of microbial contamination.  The system can be used to automate microbial testing with a more cost effective and streamline manner, and reduces the error rates produced by paper-based activity recording and batch data entry.  The BioLumix system also helps automate microbiological quality control processes.

To validate the equivalency of the BioLumix system to USP <61> or USP <2021>, over 100 types of capsules, softgels, and tablets were tested with the BioLumix system and plate count methodology at various specified levels.  The products were tested for total aerobic microbial count (TAMC), Total yeast and mold count (TYMC), and the absence of E. coli, P. aeruginosa, S. aureus, and Salmonella (objectionable organisms) in 10 grams of product.  For each assay, a 1:10 dilution was created by adding 10 grams of product to 90 mL of TSB and further dilutions were performed depending on the desired specified level.  Some of the samples were inoculated with various bacteria.


Figure 1 shows the BioLumix curves obtained for the Total Aerobic assay.  The purple curve represents an inoculated colored capsule.  All the curves along the baseline represent different kind of capsules that were not contaminated.


Figure 2 shows the BioLumix curves for the Yeast and Mold assay.  The dark blue curve represents an inoculated product. All the curves along the baseline represent different kind of capsules that were not contaminated.

 

As seen in Figure 3, the BioLumix vial design is separated into two zones: the incubation zone where the sample is present and the detection zone where the reading takes place.  Therefore, the system prevents any product interference.

Figure 3 shows two vials that contained dissolved blue capsules.  The sample on the right contained bacteria while the sample on the left was clean.

Final results are seen in the BioLumix system roughly 25-40 hours faster than the plate count method in the Total Aerobic Count assay and 40-72 hours faster in the Yeast and Mold assay.

When testing for objectionable organisms, results may be obtained several days sooner than the plate count method.  Following the BioLumix protocol, 0.1 mL of the incubated sample in TSB is added to a selective vial and data is collected in the BioLumix instrument for 18-24 hours, depending on the assay.  If detection occurs, the sample may be verified with a confirmation assay.  This procedure eliminates hours or days waiting for plate results.

The BioLumix system is faster, less labor-intensive, and more sensitive than the plate count method.  With an automated certificate of analysis generated within 48 hours, the time-to-results is reduced and allows for quick release of products.

Caron Ockerman

References:

USP <61> MICROBIOLOGICAL EXAMINATION OF NONSTERILE PRODUCTS: MICROBIAL ENUMERATION TESTS

USP <2021> MICROBIAL ENUMERATION TESTS—NUTRITIONAL AND DIETARY SUPPLEMENTS

USP <2022> MICROBIOLOGICAL PROCEDURES FOR ABSENCE OF SPECIFIED MICROORGANISMS—NUTRITIONAL AND DIETARY SUPPLEMENTS 

Pet Food and Microbiology

Why is it important to test Pet Food for microbiology?

In the past few years there have been multiple outbreaks related to pet food affecting the health of both pets and humans.  Most people associate Salmonella as a bacterium linked to food borne illness in people food, but in recent years there have been quite a few outbreaks of Salmonella in pet food that has also affected humans.  The most concerning aspect is that it primarily caused illness in small children.  It was not believed to be caused by the children eating the dog food, but having interactions with the dog.  After it was discovered that the outbreak was caused by tainted dog food, over 23,000 tons of pet food was recalled, and when the outbreak continued, the plant that produced the tainted dog food was closed down.  There was also a pet food recall based on an aflatoxin contamination.  The Center for Disease Control (CDC) categorizes aflatoxin as a naturally occurring fungal toxin that contaminates maize and other types of crops during production, harvest storage or processing1.  The aflatoxin outbreak was linked to the death of over a hundred pets.  In the past year Kroger stores recalled a wide variety of pet foods due to a possible contamination caused by aflatoxin2.

However, it is more effective to test for indicator organisms rather than to test for pathogens such as Salmonella.  Indicator organisms are used to measure potential fecal contamination of environmental samples. The presence of coliform bacteria, such as E. coli, is a common indicator of fecal contamination. Indicator organisms are typically used to demonstrate the potential presence or absence of groups of pathogens. The use of indicators is attractive because it reduces the complexity and cost of analyzing

Indicator microbes are generally selected for the following reasons:

1) They are initially abundant in the matrix to be assayed.

2) A relatively rapid, accurate, and cost effective analytical method for enumerating the indicator exists or can be readily developed.

3) A reasonably strong correlation exists between the presence/absence of the indicator and a particular pathogen or group of pathogens. The strength of the correlation will determine the effectiveness and accuracy of the indicator as a measure of pathogen occurrence.

In pet food testing is conducted for Enterobacteriaceae or fecal coliform as indicator of fecal contamination and yeast and mold as indicators for general quality and aflaxoins.

What are the advantages of the BioLumix system?

Using the BioLumix system will allow the customers to test their products not only for Salmonella and yeast/molds, but also for indicator organisms such as coliforms, fecal coliforms, Enterobacteriaceae and more.  Indicator organisms can be used to pet food manufacturing to cleanliness and sanitary issues within the facility.  Also the presence of the organisms can affect appearance, taste and texture of the pet food.  The BioLumix system can save time when testing pet food products for Yeast and Mold, instead of taking five days using traditional plates, the BioLumix system will give the same results in under 48 hours.  This can help the manufacturers to avoid a potential aflatoxin contamination by knowing if their product contains any amount of mold.  Detecting fecal coliforms is even faster and saves even more money using the BioLumix system.  Instead of running an MPN assay which will require up to 5 days of testing as well as 9 tubes of LTB and up to 9 tubes of EC Media to wait for confirmation of a positive fecal coliform.  Finally, the last confirmation step is to streak the positive EC Media to L-EMB agar plates; the BioLumix system instead requires one test vial and 1ml of the sample in order to detect a level as low at <10 cfu/gram, and can give results in under 24 hours.  Similarly, the Enterobacteriaceae test in BioLumix requires one vial instead of multiple MPN tubes required by the European method.

BioLumix Pet Food Study

BioLumix recently conducted a study of different store bought pet foods, ranging from dry dog food samples to wet (oil based) samples.  All samples matched the results for Yeast/Mold, Enterobacteriaceae, Total Aerobic Count, E. coli and fecal coliforms when comparing between the BioLumix System and traditional plating methods.  Since there are no specifications by AAFO or FDA for indicator organisms in pet foods the levels tested for Enterobacteriaceae were based on European standards for pet food.   The products were processed and tested using FDA-BAM methods3.  Only one sample came up positive for fecal coliforms, results of the BioLumix vial matched the MPN results.  Two of the samples had counts >10 cfu/g for Enterobacteriaceae and were the only ones that were above the specification level of cfu’s of the manufacturer. 

The BioLumix system detects optical changes in the test vial, presenting results of the assays as soon as detections occur with no need for involvement of an operator or a microbiologist, providing significant savings on laboratory labor. Any out-of-spec samples are flagged in red, demanding attention. The greater the contamination level, the faster the result, ensuring a rapid warning of poor-quality raw materials, finished products or any equipment line issues.

The BioLumix System showed a high correlation between the instrument results and the BAM methodology.  It simplified the microbiological testing, offers a significant reduction in time to obtain results and reduces hands-on labor due to its automation and simplicity of use.  The time to results for bacteria was hours rather than days while yeast and mold required only 48 hours instead of 5 days. 

  1.  http://www.cdc.gov/nceh/hsb/aflatoxin/
  2. http://www.prnewswire.com/news-releases/kroger-recalls-pet-foods-due-to-possible-health-risk-112125284.html
  3. http://www.fda.gov/Food/ScienceResearch/LaboratoryMethods/BacteriologicalAnalyticalManualBAM/default.htm

Microbiological Testing of Gelatin Capsules

Introduction

Two-piece capsules have been used for almost a century in the pharmaceutical field, and gelatin has been adopted as the main material of these capsules due to its excellent characteristic as a gelling agent. The gelatin dissolves under high concentration into water of a high temperature and quickly gels in room temperature. The thickness of the film made by the gelatin becomes uniform.

The gelatin capsules consist of gelatin, plasticizers and water. Modern day shells may, in addition, consist of preservatives, colors, opacifying agents, flavors, sugars, acids, enteric materials etc. A mixture derived from pork skin and bones is used in capsules.  Pork skin gelatin contributes plasticity while bone gelatin gives firmness.

One important reason for the exclusive use of gelatin for making hard and soft capsules is its solubility characteristics in stomach fluids. It absorbs cold water readily, though the rate of absorption depends upon moisture content of gelatin. Bloom Strength is an empirical gel strength measure which gives an indication of the firmness of gel. The plasticizers used are glycerin, sorbitol etc.  Preservatives, if included, are generally a mixture of methylparaben (4 parts) and propylparaben (1 part) to the extent of 0.2%. Flavors, if added, should not exceed 2% and are generally ethyl vanillin or essential oils. Sugar, if included, may be up to 5% to give the gelatin shell desirable chewable characteristics.

Microbiology Testing

Each incoming lot of capsules needs to be tested using USP <61> and USP<62>. The total aerobic bacterial count should not exceed 3,000 cfu per gram, the combined yeast and mold counts along with Bile-Tolerant Gram-Negative Bacteria should not exceed 300 cfu per gram.  Material must also meet the requirements of the tests for absence in 10 grams of Salmonella species, Escherichia coli, and Staphylococcus aureus.

Challenges of Current Methodology

Testing gelatin capsules for microbiology might result in several challenges.  The 1:10 dilution of the product has high viscosity and is sometimes difficult to pipette. Many capsules have vivid colors that interfere the reading of the plates. 

The current methods used in microbiology originated over 100 years ago.  There have been limited improvements in methods used for microbiological testing in the last decade. The current USP methodology is slow, requiring up to 5-7 days for product release, is manual, and in many cases is inaccurate.  Paper-based QC laboratory processes can be expensive, error-prone, time and labor-intensive.  

Rapid microbiological methods (RMM) offer a cost effective alternative to USP methodology.  With an RMM’s high degree of automation, significant reduction in time to results, faster product release, and improved process control, while providing enhanced accuracy, better repeatability, and total automation

BioLumix Alternative

The BioLumix System simplifies testing, expedites time to results, reduces the testing cost and accelerates product release while providing better control of microbial contamination.  The system can be used to automate microbial testing with a more cost effective and streamline manner. The system reduces the error rates produced by paper-based activity recording and batch data entry.  The BioLumix system also helps automate microbiological quality control processes.

The BioLumix technology is based on continuous monitoring of changes in color or fluorescence as a result of microbial metabolism in ready to use test vials. The results are presented as soon as detection occurs without any involvement of the operator. The fully automated system offers a paperless operation with increase efficiencies.

The key to the technology is the two-zone ready to use vials which eliminates any product interference.  Many types of gelatin capsules were tested in the BioLumix system for total aerobic bacterial count, combined yeast and mold counts, Bile-Tolerant Gram-Negative Bacteria, and for absence in 10 grams of Salmonella species, Escherichia coli, and Staphylococcus aureus.  As can be seen in the figure, there is no product interference even with capsules containing the most vibrant colors.  All assays yielded clear results that correlated well with the USP methodology.

Key: Dark Blue-clear capsule;Green- Brilliant Red Capsule; Light Blue-Brown capsule;Red- Teal capsule; Purple-Inoculated Brilliant Red Capsule.

The BioLumix system is validated against the USP methodology.  All assay results are complete in 48 hours with an automated Certificate of Analysis; resulting in faster product release.