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