Explore this issueApril/May 2011
The nature of food and foodborne illness has changed dramatically in the United States over the past century. While various technological advances such as pasteurization and proper canning have all but eliminated some diseases, new causes of foodborne illness are continually being identified.
The Centers for Disease Control and Prevention (CDC) estimates that roughly one out of six Americans, or 48 million people, are sickened by foodborne illness each year. Another 128,000 are hospitalized, and approximately 3,000 die of foodborne diseases every year.
Further, it is estimated that reducing foodborne illness by just 10% would keep about 5 million Americans from getting sick each year, while preventing even a single fatal case of E. coli O157 infection could result in significant cost savings.
As known pathogens continue to build resistance to available therapeutics and new pathogens emerge around the globe, ongoing changes in demographics, globalization, food production and processing, and food consumption patterns require a comprehensive, science-based approach to food safety assurance and testing. Diagnostic labs need approaches that will quickly and reliably detect pathogens with minimal risk for error. Because of this need, there is growing interest in the application of bacteriophage technology in diagnostic testing for food safety.
Identifying Common Pathogens
Outbreaks of disease caused by foodborne pathogens such as Salmonella, E. coli, Listeria, and others clearly have an enormous impact on public health. Unfortunately, effectively eliminating these ever-evolving bacteria from food processing plants can be difficult and costly. Despite rigorous controls put in place by experts at the U.S. Department of Agriculture and the U.S. Food and Drug Administration, we continue to see growth in the number of cases of food-related disease in the United States and around the world. Consider the following:
- Salmonella, a bacterium that causes one of the most common intestinal infections in the United States (salmonellosis) is implicated in more than one million cases of foodborne disease annually in the United States, according to a 2011 report. Of these cases, approximately 20,000 result in hospitalization and 378 result in death.
- Once regarded as a rare serotype, Escherichia coli O157:H7 (E. coli O157:H7) today is one of the major contributors to foodborne disease in industrial countries. It has been estimated that each year E. coli O157:H7 causes approximately 62,000 cases of foodborne disease and approximately 1,800 foodborne illness-related hospitalizations in the United States.
- Disease caused by Listeria monocytogenes (listeriosis) primarily affects pregnant women, newborns, and adults with weakened immune systems and has one of the highest fatality rates among all foodborne bacterial diseases.
Many available approaches for identifying foodborne pathogens are sufficient and accurate when used correctly. However, associated time lags and/or potential for human error when facilitating the tests can compromise the test results, as can a company’s ability to respond in a manner expedient enough to avoid outbreaks. For instance, results obtained from traditional microbiological culture techniques can only be obtained within three to five days. Additionally, test performance and accuracy can be negatively affected by the number of lab technicians and other specialists physically handling the samples.
Other technologies, including DNA-based polymerase chain reaction assay, immuno-assay, and immuno-latex agglutination, have been developed to address some of these issues and, in most cases, can obtain results within 48 hours. Faster detection, however, is necessary to better manage and prevent outbreaks by stopping the distribution and consumption of infected food more quickly.
Phages are highly specific viruses that use their host bacterial cells as factories for their own replication and have the ability to display peptides or proteins on their surfaces—a technology known as phage display.
Detection methods utilizing bacteriophages (phages) can allow food producers to rapidly detect any bacterial pathogens present in their products. These methods also provide an effective means to significantly reduce or prevent contamination of foods with specific pathogenic bacteria, thereby eliminating the risk, or significantly reducing the magnitude and severity, of foodborne illness caused by the consumption of foods contaminated with those bacteria.