Stopping outbreaks--whether caused by biological warfare or a salmonella-contaminated salad bar--would be much easier if we could quickly detect the pathogens in real time. But real-time analysis isn't possible just yet, said molecular microbiologist Deborah Newby, of the U.S. Department of Energy's Idaho National Engineering and Environmental Laboratory. Even the very best of today's detection technologies require at least a 15-minute wait for each batch of samples.
Newby, whose research at the INEEL supports DOE's national security mission, will present a review of pathogen detection techniques at Wednesday's American Society for Microbiologists annual meeting in Washington, D.C. . The colloquium is 293, titled (Re)emerging Biothreats and Protection of Public Health: State of the Art Sampling, Detection and Remediation of Pathogens in the Environment.
"Most of the science for pathogen detection has been driven by the military because they've had the dollars and the need," Newby said. But world events over the past couple of years have heightened the risk awareness of outbreaks in both the public and the government. Whether an outbreak is natural or intentional, the impact on the public and environment can be devastating.
During 2001, 22 people in the United States were diagnosed with anthrax transmitted through the mail. Five people died. This kind of attack took the country by surprise and challenged the nation's ability to respond. The Laboratory Response Network (a network of labs that can perform analyses during an emergency) was inundated with 2,500 suspected anthrax samples to analyze from 46 states, and the Centers for Disease control responded to 8,860 calls between Oct. 8 and Oct. 31, 2001. Ultimately, more than 32,000 people were advised to take Cipro (trademark for the drug ciprofloxacin) as a precaution against the disease. The need for better and faster pathogen detection techniques is clear.
The challenge in detecting a pathogen--a disease-producing microorganism--is that researchers have to know the DNA signature of the microorganism. "You have to know what you're looking for in order to find it," said Newby. That's hard enough, but genetically engineered pathogens--microorganisms with DNA that has been modified to make it more virulent in some way--may not immediately appear different from normal microorganisms. "It's possible to spoof detection systems," said Newby.
Researchers have to know where to sample, the best way to sample, and how much to collect in order to get accurate results from analyses. And they've got to be able to discern when enough of a particular pathogen is present to trigger an outbreak. That can be complicated because many biological weapons have their genesis in very common organisms.
Ideally, analysis needs to be detailed enough to determine what strain of the pathogenic organism is present. That helps researchers differentiate a naturally occurring organism from one that has been genetically modified. Strain analysis also helps researchers to track the transmission of the organism as it is passed from one animal to another.
It's also challenging to detect the viability of the pathogen. For many pathogens, "If the organism is present, but not alive--it can't infect anyone anymore," said Newby. "If the organism is alive, however, the risk or threat of the pathogen is still active."
No analytical technique can beat culturing, the "gold standard" for identifying a microorganism. "But the lag time on cultured analytical results can range from hours to days," said Newby. Culturing is great for confirming the diagnosis of another technique, however.
Some detection systems--from hand-held analyzers to larger detectors--are showing promise, but still can't provide real-time analytical results. "The best systems out there still take at least 15 minutes per sample batch, assuming there's no sample preparation time," said Newby.
Newby and INEEL molecular biologist Frank Roberto are developing a quick, safe, accurate method to detect the brucellosis strain, B. abortus, in the field. Roberto and Newby are designing a DNA-based field assay using a field-portable, real-time polymerase chain reaction (PCR) system. Brucellosis is an infectious bacterial disease caused by the brucella species and can be transmitted from animals--such as cattle--to humans through contact with reproductive tissues or consumption of infected, unpasteurized milk. In animals such as cattle, bison, elk, sheep and goats--and in some rare instances, seals--the disease can cause spontaneous abortion and an inability to conceive in females, and epididymitis in males. According to the Centers for Disease Control and Prevention, symptoms of brucellosis infection in people include fever, night sweats, undue fatigue, anorexia, headache, and joint pain. It is seldom fatal, but there is no effective human vaccine.
Research by Newby and Roberto was recently accepted for publication in Applied and Environmental Microbiology, and will appear in print sometime this year.
Can we ever get to real-time analysis? "Maybe," said Newby. "There are real science advances that need to be made to get us to that point, and we don't completely understand what they are yet."
The INEEL is a science-based national laboratory dedicated to supporting the U.S. Department of Energy's missions in environment, energy, science and national defense. The INEEL is operated for the DOE by Bechtel BWXT Idaho, LLC.
Materials provided by Idaho National E & E Laboratory. Note: Content may be edited for style and length.
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