Meat Microbiology Trends: The Future is Now
By An interview with Dr. William Brown, ABC Research Corp.
Pathogenic bacteria, bovine spongiform encephalopathy (BSE), avian flu. You name a microbiological challenge faced by the meat and poultry industry in the past 40 years, and Dr. William Brown has seen it, analyzed it and researched the science-based solutions for it.
As president of ABC Research Corp., the Gainesville, FL-based ISO 17025 accredited, full-service microbiological and chemical food laboratory that he founded in 1967, Dr. Brown lends his expertise to a variety of food processing plants, retail and distribution companies, foodservice operations, trace associations and universities. During his more than four decades of experience in the food industry, Dr. Brown also held positions as vice president research at John Morrell & Co. and as an instructor at North Carolina State University. Among his many professional affiliations, Brown served on the U.S. Department of Agriculture (USDA) National Advisory Committee on Microbiological Criteria for Food, is executive director of the Southeastern Meat Association, and is a past member of the Technical Advisory Committee for the U.S. Poultry & Egg Association.
Dr. Brown spent some time with Food Safety Magazine to share his insights on some of today’s pressing issues faced by meat and poultry microbiologists and shares his recommendations on how to meet these and future challenges.
Food Safety Magazine: In your experience, Dr. Brown, what are the top food safety issues of concern to today’s meat and poultry producers and processors in terms of microbiological hazards?
Brown: There are three areas that I think are the top food safety issues in the immediate future. The first issue of concern to food microbiologists and the food industry is bacterial pathogens because we know that these microorganisms can cause illness and even death. The two most prominent pathogens of concern, and that certainly cause the most problems for the meat and poultry industry, are E. coli O157:H7 and Listeria monocytogenes. The second area of concern to meat and poultry producers, processors and microbiologists is viruses, specifically hepatitis A and the avian flu. The third issue that I believe will be important to address is prions due to their association with Mad Cow disease.
FSM: In terms of these issue areas, what kinds of developments are underway that will help the industry successfully address these challenges?
Brown: In terms of E coli O157:H7, there are a few things that will help. First, we need to take the testing from slaughter plant back to the farm. What I mean by this is that we need to test the animals to determine whether they are positive or negative for the pathogen before sending them to the meat packing plant. In terms of control measures that can be taken to reduce the incidence of E. coli O157:H7 at the farm level, there are a few developments that should help. One is the addition of probiotics to the feed that appears to help reduce the shedding of E. coli O157:H7. Also, there has been some recent Canadian research on vaccines that could be given to the animals on the farm to reduce shedding.
Since Listeria monocytogenes is a foodborne illness causing pathogen that is found literally everywhere, it is proving to be a difficult challenge for many types of food processing and handling operations. In addition, Listeria monocytogenes has a reputation for staying in a processing plant and continuing to be a source of infection. For example, we saw a Listeria strain that caused the death of a woman in Texas and eight or 10 years later, the same strain was found in the processing plant where the contaminated product was manufactured. Recently, some poultry trucks were checked for Listeria monocytogenes and the pathogen was found on 100 percent of them. This is a post-processing contamination problem that the industry really needs to work on.
In terms of regulatory developments, the USDA Food Safety and Inspection Service (FSIS) issued in 2003 an interim final rule, “Verification Procedures for the Listeria monocytogenes Regulation and Microbial Sampling of Ready-to-Eat Products for the FSIS Verification Testing Program,” which outlines some of the ways in which the industry can develop approaches to combat this pathogen. The interim final rule requires manufacturers of medium- and high-risk RTE meat and poultry products to develop written programs to control Listeria monocytogenes and to verify the effectiveness of those programs through testing. The rule establishes three risk-based alternatives for categorizing RTE products and encourages plants to install new technologies to eliminate or reduce the growth of Listeria monocytogenes. The rule also states that establishments must share testing data and plant generated information relevant to their controls with the agency.
With regard to viruses, our ability to detect and characterize these in foods is not as advanced as our ability to test for pathogens in foods. Improvements in virus testing will only come through increased emphasis at the basic research level at research laboratories. There are some basic research problems that need to be looked at, especially in the case of the avian flu. As we’ve seen, the avian flu has been picked up in a couple of poultry farms in Delaware, and very recently, the avian flu was found in a flock of poultry in Texas. Although the avian flu is not a new problem, in previous cases or outbreaks, we’ve been able to control and contain it. However, with the increasing population and travel between the U.S. and rest of the world, coupled with increased incidence of cross-contamination arising from people going back and forth between chicken farms, it is becoming a much more difficult and serious problem with which we must contend.
Hepatitis A is a problem with people not washing their hands after they go to the bathroom and the virus is passed on when these people handle foodstuffs. We know that the problem can be partially solved by requiring and implementing good personal hygiene practices and plant sanitation methods in food processing operations.
Meat microbiologists and the industry need to look at prions from a couple of standpoints. Recently, prions have been given a lot of publicity because of Mad Cow disease but they are also getting a lot of attention from researchers because they may also help us in the treatment of abnormal brain functions. There is some interesting information, for example, that has been published recently suggesting that prions may be involved in Parkinson’s and Alzheimer’s disease. The proteins are the workhorses of living things, and the human body probably makes about 50,000 different proteins for tasks ranging from building bones and muscle to digesting food and thinking. I think there may be an opportunity for researchers not only to solve the Mad Cow disease problem but also some of the brain function problems in our elderly population that are being reported.
FSM: What kinds of methods are being used to advantage by today’s meat and poultry microbiologists in terms of pathogens and viruses?
Brown: As I mentioned, viruses are extremely difficult to deal with and most food testing facilities are not able to do virus research, so this is typically conducted at government or university laboratories. It’s a tissue culture technique in which the tissue sample is taken from a live animal or live source, and the virus is grown on culture media and then compared to the strains we know about. Bio-testing is expensive, time-consuming and difficult to do in terms of the amount of work you must to pinpoint a particular strain. You cannot conduct virus testing rapidly or overnight like you can with pathogens. Typically, it will be five to seven days before test results are available. In the food industry, this amount of lag time to test result is unhelpful.
We do have several rapid microbiological methods that are in use by today’s meat and poultry microbiologists that have proven helpful in the identification and detection of pathogens. Techniques such as enzyme-linked immunosorbent assay (ELISA) and genetic-based techniques such as polymerase chain reaction (PCR), which have sped up and made more precise the pathogen testing in the laboratory and in the plant. At our laboratory, we’re using a technique called REP-PCR, which is a microbial genetics technique that allows you to determine the relationship between cultures or species of organisms. These are the types of rapid methods that will continue to be developed and used by food microbiologists.
Specifically with regard to Listeria monocytogenes, the best defense is a good offense. Since the organisms is ubiquitous, food processors must control the plant environment and the processing surfaces. With Listeria, you’ve got to heat it to eliminate it in the processing itself and after that you must control it in the post-packaging environment—this is where the real challenge lays in controlling Listeria monocytogenes. As a result, the processor needs good sanitation practices in place and environmental hygiene monitoring methods to verify that equipment and other harborage niches have been adequately cleaned and sanitized. Where microbiologists can play an important role in the control of Listeria monocytogenes is at the research and development stage of food production. We need more development in terms of adding antimicrobials to the food product to keep Listeria from reproducing and growing to large numbers. We know that Listeria monocytogenes grows at low temperatures and that it can grow on products that are under refrigeration. The way to control this is through the use of food additives, and there are some that have been fairly effective. Potassium or sodium lactate and sodium diacetate have been used in combination to control the growth of Listeria in various foods, including meat and poultry products.
FSM: What should meat processors look for when developing an appropriate BSE sampling/testing approach?
Brown: In my opinion, BSE is a problem more from a publicity standpoint that from a real-world problem standpoint. I say this because if you go back to 1986 when Britain first began working to solve its BSE problem, they destroyed approximately 600,000 animals by incineration and predicted a few hundred thousand cases of variant Creutzfeldt-Jakob disease (vCJD). In fact, we’ve only documented about 140 total cases worldwide, so BSE has not turned out to be the problem everyone thought it would be.
Having said this, I think the chances of the U.S. finding incidence of BSE were fairly good because the number of cattle imported from England to Canada to the States indicated that sooner or later we would find a BSE-positive cow. I think the U.S.’s sampling plan was minimal and when you are talking about 20,000 cows being tested for BSE out of 35 million killed, you don’t have a very statistically valid number. FSIS ann-ouncements on the government’s plans to institute increased BSE surveillance and testing will certainly help.
A few companies, such as Bio-Rad Laboratories and Prionics AG, offer BSE rapid detection tests that have been widely used in Europe and Japan. These test methods have not been approved for use in the U.S., however. We’ve been using a five-day method and then sending the samples to Europe for confirmation. Recently, both the Canadian Food Inspection Agency (CFIA) and the USDA announced that their agencies are working to approve rapid tests for use in their government BSE testing programs. Ultimately, I believe that industry needs to have at their disposal a method to test the blood of the animals before they come to the slaughterhouse, because once they get to the slaughterhouse it is extremely difficult to do any testing.
FSM: What are the longer-term challenges posed by microbiological hazards to the meat industry?
Brown: One problem is that perception becomes reality, and that gets us in trouble because we spend our time and energy and newspaper space on issues that probably are not the most important ones from a scientific standpoint. We need to commit and spend more money on basic research, including research on live animals and prions, as well as on practical methods to control microbiological hazards. Historically, the meat industry only makes a small profit as percent of sales and generally, it has not had a lot of money at its disposal to spend on research. But it is im-portant that the industry solve some of these problems by stepping up to the plate and contributing the funds needed to get on with basic research to develop good prevention, control and detection technologies. We can’t wait for the government to furnish the funding.
This is not to say that the industry has not successfully come to the plate on food safety issues. In fact, the meat and poultry industry is not given enough credit for its support and implementation in the last 15 years of the Hazard Analysis and Critical Control Points (HACCP) system, which has gone a long way to reduce the pathogen problem in meat and poultry products.
The fact is that we’re in an ever-changing scientific landscape with an immense body of knowledge and information becoming available at a staggering rate. Although keeping up with all this data is challenging, there are some excellent resources for meat microbiologists who want to stay abreast of the topical issues we’ve discussed here. USDA has put together a food safety research agenda (www.ars.usda.gov), which is a good document to read, and the Council for Agricultural Science and Technology’s (CAST) latest issue paper, Intervention Strategies for the Microbiological Safety of Foods of Animal Origin, focuses on intervention strategies for the microbiological safety of foods of animal origin.
It is an exciting time to be a meat microbiologist, and it is an exciting time for food safety research in this area. Through increased research, we will gain a better understanding of plant, animal and microbial genetics—there is so much opportunity for us to discover solutions to today’s microbiological challenges. But Mother Nature doesn’t let you in on her secrets too easily, and we must continue to strive to unlock those secrets.