Autonomous system for pathogen detection and identification Page: 4 of 11
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authorities is needed to be able to respond to an alarm - relatively inexpensive HEPA-filtered
masks could- be donned in the detect-to-warn mode, and quarantine/limited travel of exposed
persons would be the appropriate in the detect-to-treat mode, followed by the administering of
selected antibiotics, etc.
To be acceptable, the autonomous system will have to satisfy the following criteria:
1. It must be able to run, unattended, for 24-hour periods (and much longer periods than this are
2. It must be capable of the automatic, positive detection, identification, and quantification of the
3. It must be capable of positive detection and identification of the items listed under #2 at aerosol
concentrations of 1 agent-containing particle/liter of air (ACPLA) or greater in the presence of
all normal environmental airborne backgrounds, including diesel exhaust, smoke, pollen, non-
pathogenic bacteria and spores, etc.
4. It should detect and identify in less than 20 minutes for 5 ACPLA concentrations or higher,
and less than 35 minutes for 1 ACPLA concentration. Quantification of the threat- is highly
5. It must have a false-alarm rate that is less than 1 per year.
We are currently working to build such an autonomous system, which we call the "Bio-
Sentry", using flow cytometry for surface-recognition assays, PCR for nucleic-acid-based
assays, and sample collection/preparation instrumentation, along with commercial bio-aerosol
collectors. We have selected the flow-cytometric and PCR assays because they have proven
themselves, worldwide, as the most powerful assays, other than cell culture. We are not
including cell culture, due to its long duration for growth of the samples, its labor-intensive
identification, and its inability to detect non-culturable organisms.
Performance considerations for B. anthracis (B.a.)
Starting with 1 ACPLA of B.a., where one particle for B.a. could be assumed to consist of
15 spores, then a person, at rest (roughly 100 cal/hour being consumed at 33% overall
efficiency), exchanging room air through the alveoli of his lungs at roughly 5 1/min, assuming
high efficiency for deposition and germination of spores in the lungs, would receive a life-
threatening dose, estimated to be 8000 to 10,000 spores, in roughly 100 minutes. If the person
were more active and, therefore, breathing harder, he would obviously receive the life-
threatening dose faster. Using these estimates, for a person functioning at light levels of activity
in an office building for an entire work day, a 0.1 ACPLA of B.a. aerosol would probably be the
lower limit for causing a life-threatening dose. Therefore, we will determine what level of
performance would be required in the Bio-Sentry to detect all aerosol concentrations of 0.1
ACPLA and higher.
Assuming only 0.1 ACPLA, a collector running with 1000 1/min air throughput at 50%
collection efficiency of the spore particles, collecting over a period of five minutes into a volume
of 1 ml of water, would accumulate 2.5 X 102 particles into its collection fluid. If the
subsequent fluidics subsystem that handled and prepared the collected sample (using sonication
or other process) were able to disrupt the clumps of spores from each other with 70% efficiency,
then the starting concentration of spores after the five-minute collection would be roughly
2.5 X 103 spores/ml. Under field-test conditions, the LLNL miniFlo correctly identified and
quantified all spore unknowns, over the full test. range of 103 spores/ml through 106 spores/ml,
using a single-target assay for bacteria'.
Autonomous System for Pathogen Detection and Identification Nov98
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Belgrader, P; Benett, W; Langlois, R; Long, G; Mariella, R; Milanovich, F et al. Autonomous system for pathogen detection and identification, article, September 24, 1998; Livermore, California. (digital.library.unt.edu/ark:/67531/metadc716580/m1/4/: accessed July 18, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.