Forensic Microbiology

The use of pathogenic agents and toxins as bioweapons to commit terrorism and biocrimes has been occurring for more than two millennia. Targets are humans, animals, and plants in which serious harm, economic damage, fear, and social disruption can result from an attack. Law enforcement has a responsibility to protect against this threat by providing deterrence, prevention, interdiction, criminal investigation, and providing forensic evidence for convictions. In response, the field of microbial forensics has been created. Microbial forensics is a scientific discipline that examines microorganisms, toxins, pests, prions, or their associated ancillary products for source attribution. The field is built upon the principles applied to epidemiological investigations. A number of nucleic acid and non-nucleic acid methodologies can be employed to characterize microbial evidence. However, obtaining a level of identification comparable to human DNA analyses may not be routinely possible with microorganisms or their toxins. Thus, concepts such as a genetic 'fingerprint' or unique identification may never be possible because many microorganisms reproduce asexually; at least portions of their genomes are inherited in a clonal fashion. There are other genomic and ecologic dynamics of microbes to consider, such as horizontal gene transfer, the availability of less than optimal population, and phylogenetic data, and, in some instances, limited historical and epidemiological information that may impact the ability to identify a unique source for attribution. By understanding the limits of analyses and data, reliable information can be obtained to assist investigations.