Science Needs for Microbial Forensics Developing Initial International Research Priorities (2014) / Chapter Skim
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5 Sampling and Preservation Methods
5 Sampling and Preservation Methods
Pages 97-116
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From page 97... ...
The authors of this report stated that the collection and preservation of vital microbial forensic evidence is a critical element of successful investigation and ultimate attribution subsequent to a biological event. A primary goal of collection is to obtain sufficient biological agent to support both species/strain or toxin identification for critical public health decisions and complete signature characterization for valuable lead information.
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From page 98... ...
The key messages of his presentation were that microbial forensics is a multidisciplinary field developed to serve law enforcement needs and provide criminal attribution. However, although it was initially motivated by biocrimes and bioterrorism, there are many new applications for microbial forensics that create both opportunities and challenges.
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From page 99... ...
conducts stud ies and laboratory experiments to fill in information gaps to better understand current and future biological threats; to assess vulnerabilities and conduct risk assessments; and to determine potential impacts to guide the development of countermeasures such as detectors, drugs, vaccines, and decontamination technologies. Neither NBFAC nor NBTCC has as its primary responsibility to conduct research on microbial forensics.
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From page 100... ...
Matts Forsman of the Swedish Defense Research Agency also related that in Sweden, first responders may include police, fire, and rescue squad personnel, but a specially trained bomb squad is then called in to sample, pack, and transport samples to the Swedish National Laboratory for Forensic Science. Some generic sample matrices for evidence collection appear in Box 5-2.
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From page 101... ...
Standardization is needed for handling bulk as well as minute samples. As pointed out by Dana Kadavy, because microbial forensic investigators deal with such a broad range of sample matrices, they should maximize cleanup procedures to enhance typing success.3 A laboratory may need more than one sample processing method, particularly if it receives a variety of samples that reside in different matrices.
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From page 102... ...
But in operational terms, collecting samples is complicated. First, the investigator must determine how to optimize the collection of the clinical or environmental samples from the various sources and how to preserve them in an appropriate manner.
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From page 103... ...
Hamilton noted that there are a number of potential starting points for collaboration. These include the public health, veterinary, agricultural, food safety, environmental, defense, law enforcement, industry, and academic communities; international organizations with accrediting agencies and governing bodies; and sovereign states.
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From page 104... ...
Bruce Budowle discussed sampling and preservation in the food and agriculture context. His purpose was to provide a sense of the range of evidence sampling and collection possibilities that a microbial forensic investigation might confront and the outlines of a comprehensive plan for approaching such varied circumstances and challenges.
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From page 105... ...
Under certain conditions, the agent may actually be destroyed. A general approach to sampling appears in Box 5-5A, and a more focused approach -- in this case, for wheat streak mosaic virus -- appears in Box 5-5B.
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From page 106... ...
, but owing to myriad possibilities that investigators may encounter, there is not a single sample collection and preservation strategy that is suitable in all situations. A key step in the comprehensive plan is to identify experts in advance so that when an event occurs, investigators can quickly develop consultation plans before they begin collection.
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From page 107... ...
BOX 5-6 Comprehensive Plan for Sampling and Collection • evelop a mechanism for quickly formulating a "consensus" analytical plan D when a new sample (or set of samples) arises.
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From page 108... ...
If it is a covert event, and the first indication is sick people appearing in an emergency room, collecting environmental samples 1 to 3 weeks after the fact may not accomplish much. On the other hand, if the release point is determined, trace evidence and dispersal items may still be accessible.
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From page 109... ...
Similarly, porous surfaces, such as fabric and carpeting, have their own characteristics. Although the number of potential surfaces is unlimited, it is only possible now to validate sampling methods for a small number and then extrapolate the experience as necessary.
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From page 110... ...
Morse was asked to comment, in terms of validating collection methods, how much confidence he has that there are no spores when he gets a zero response from sampling a room, and how he establishes probability or statistical confidence limits. Morse responded that a negative result only means that there were no viable spores detected, but one does not know if there are spores below the limit of detection; current sampling methods will detect less than 1 spore per cm2 on a surface.
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From page 111... ...
Ministry of Defense's Defense Science and Technology Laboratory based at Porton Down. This facility provides chemical and biological analysis capability on behalf of defense and security customers, including the military and law enforcement.
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From page 112... ...
Rees noted that the Laboratory has frequently worked with defense and security customers to address the requirements for chemical and biological analysis and attribution capability that support the different communities' needs, which appear to be very similar. All require highconfidence information that enables defense customers to make strategic decisions and security customers to support the criminal justice system.
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From page 113... ...
During the first month in Iraq, the equipment was inoperable because they had not been supplied with a transformer adaptable to Iraqi electricity. Their immunological methods originally included hand-held lateral flow immunoassay devices, but their unacceptable false-positive rates for environmental samples prohibited their use.
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From page 114... ...
For example, there are roughly 36 genes that encode tetracycline resistance; however, even if inspectors look only for that phenotype, the PCR analysis would need to be a highly multiplexed assay. Moreover, frequently only nonviable samples can be
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From page 115... ...
The Iraqis had legitimate castor oil plants, for example, and inspectors needed to determine if the ricin being produced was still active, if it was heat-inactivated, or if efforts were being made to extract it. A PCR assay cannot provide that information.
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