By ECBC CommunicationsJune 10, 2014
ABERDEEN PROVING GROUND, Md. -- According to the Centers for Disease Control and Prevention one in six Americans -- about 48 million people -- get sick, 128,000 are hospitalized, and 3,000 die of food borne diseases every year.
For men and women in the U.S. Army who are exposed to countless threats and unpredictable conditions, these numbers could dramatically increase.
That's why one of the U.S. Army Public Health Command's main missions is to ensure the safety of food and water for the U.S. Army. PHC recently completed a successful project with the Edgewood Chemical Biological Center to demonstrate the use of a Mass Spectrometry Proteomics Method to identify and classify bacterial pathogens in food.
Scientists at the US Army PHC Region South, Food and Diagnostic Laboratory in San Antonio, Texas, sent 150 blind samples of mashed potatoes to ECBC for testing. Within these samples, 75 were spiked with Salmonella.
ECBC used the MSPM to identify and differentiate which samples contained the bacterium and which did not. ECBC scientists Rabih Jabbour, Samir Deshpande, and Pat McCubbin, all of ECBC's Point Detection Branch, were able to correctly identify all 150 samples and distinguish contaminated samples from non-contaminated ones.
This successful outcome has led to two significant next steps in the development of this technology for food detection.
First, PHC has funded the team to expand their work to detect toxins in mashed potato samples, a project currently underway. Second, the team will be transitioning the MSPM equipment to a PHC laboratory in Camp Zama, Japan, to support the ECBC and JPEO Joint United States Forces Korea Portal and Integrated Threat Recognition program (JUPITR ATD).
"The team had not undertaken a study with a sample set quite this large before," said Mary Wade, ECBC Point Detection Branch Chief. "We have received and analyzed blind samples from outside organizations, but not 150 samples at once. This program was a great validation for robustness and capabilities of the MSPM."
MSPM is a technique that provides structured sequence information of a given protein. All proteins consist of amino acids arranged in a specific sequence; changing the arrangement generates a new protein.
Mass-spectrometry interrogates digested protein fragments (peptides) and provides structural information about the exact arrangement of the peptides in the sample. Then using the detection and identification algorithm known as ABOid, the sample peptides are compared to its theoretical proteins present in the protein sequence database, which is curated from various public sequence repositories like the National Center for Biological Information, European Molecular Biology Laboratory, and DNA Data Bank of Japan, to distinguish whether bacteria, toxins, fungi or viruses are present.
The MSPM and ABOid were able to both detect and identify that Salmonella was present, as well as other organisms that were present in the background matrix.
"We screened first specifically for Salmonella, and Dr. Samir Deshpande, especially spent a lot of time delving into what else we could find within those samples," Wade said.
As opposed to other detection methods, MSPM takes minutes to detect and identify rather than days, which is an important function in food detection. Other than its current validation in food, the MSPM has been successful with detecting viruses, toxins and bacteria in buffers, microbial media as well as more complex environmental and medical matrices such as water, air, soil and blood.
With identifying Salmonella in mashed potatoes as a starting point, PHC is now funding the Point Detection Branch to use MSPM to identify toxins, specifically Botulinum Toxin, in mashed potato samples.
Wade said once the team can successfully validate toxin detection in mashed potatoes, she would like them to begin testing samples of more complex foods such as milk or peanut butter, which has higher fat and protein contents, and meats or sandwiches which are not uniform.
At the moment, mashed potatoes are being used as a proof concept.
"Mashed potatoes are the commonly used food type for evaluating a diagnostic technique for identifying pathogens in food," said Wade. "It is a starch-based consistent food type that is best for proof-of-concept experiments as the target and the mashed potatoes can be easily homogenized for equal distribution throughout the sample."
In addition to expanding the type of testing, Wade said the team is excited to demonstrate how Mass Spectrometry can support the JUPITR ATD Program.
The JUPITR ATD program is a multi-year program geared toward providing biological surveillance capabilities to the Asia-Pacific region. The team will show PHC personnel in Camp Zama how the system works and help their laboratories get their system up and running for use in that region.
The team will demonstrate how Mass Spectrometry can identify biological pathogens through doing the same blind test with mashed potatoes. Additionally, the team will also demonstrate how Mass Spectrometry can be used to prove false positive results from hand held assays.
Although current MSPM food application testing is with the US Army, the method could be easily transitioned for civilian applications by organizations such as the Centers for Disease Control, the Food and Drug Administration or the U.S. Department of Agriculture.
The Point Detection Branch plans to publish their findings from the Salmonella blind test in an upcoming Technical Report and peer-review journal publication, both currently being drafted. They expect to be completed with the blind toxin testing in September 2014 and plan to publish those results as well.
ECBC is the Army's principal research and development center for chemical and biological defense technology, engineering and field operations. ECBC has achieved major technological advances for the warfighter and for our national defense, with a long and distinguished history of providing the Armed Forces with quality systems and outstanding customer service. ECBC is a U.S. Army Research, Development and Engineering Command laboratory located at the Edgewood Area of Aberdeen Proving Ground, Maryland. For more information about the Edgewood Chemical Biological Center, please visit our website at http://www.ecbc.army.mil or call (410) 436-1159