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May 31, 2010

BehindTheMedspeak: CSI Bacteria

Long March 16, 2010 Associated Press story short: "Each one of us leaves a unique trail of bugs behind as we travel through our daily lives."

FunFact: "The average human hand contains about 150 species of bacteria with only about 13% shared by any two people."

Here's the article.


Forensic Role For Bacteria?

Warning to criminals: Rubbing out your fingerprints may no longer be enough. Your germs could still give you away.

It turns out the colonies of bacteria that live on people's hands are highly personal to each individual.

That means forensic experts could one day use those bacteria to prove who has touched an object, researchers report in Tuesday's edition of Proceedings of the National Academy of Sciences.

"Each one of us leaves a unique trail of bugs behind as we travel through our daily lives. While this project is still in its preliminary stages, we think the technique could eventually become a valuable new item in the toolbox of forensic scientists,'' lead author Noah Fierer, of the University of Colorado, said in a statement.

In one test, the researchers swabbed computer mice that hadn't been used in 12 hours and compared the bacteria with those collected from the hands of the computer owner and 270 other randomly chosen people. The closest match was to the computer owner.

In addition to smudged fingerprints, the technique may also be useful in determining who has touched things like fabrics and highly textured materials, the researchers said.

Overall, the researchers said, their technique was between 70% and 90% accurate. Researchers said accuracy is expected to improve as the technique becomes more sophisticated.

This analysis is something that scientists couldn't have done even two years ago, noted Prof. Fierer, an assistant professor in the ecology and evolutionary biology department at Colorado.

The average human hand contains about 150 species of bacteria with only about 13% shared by any two people, the research team found in earlier studies.

The new research was funded by the National Science Foundation, the National Institutes of Health, the Crohn's and Colitis Foundation of America and the Howard Hughes Medical Institute.

Here's the article.


Lead author Fierer told USA Today, "We're just coated in bacteria." 

But, said Fierer, "I don't think at this point any criminals need to be worried about leaving bacteria on objects."

Which leads me to wonder if smart transgressors of the 2020s will recolonize themselves with the bacteria of their prospective targets prior to beginning their nefarious activities.

Sounds a lot less expensive (and painful) than having one's fingerprints erased.


Here's the abstract of the paper cited above.


Forensic identification using bacterial skin communities

Recent work has demonstrated that the diversity of skin-associated bacterial communities is far higher than previously recognized, with a high degree of interindividual variability in the composition of bacterial communities. Given that skin bacterial communities are personalized, we hypothesized that we could use the residual skin bacteria left on objects for forensic identification, matching the bacteria on the object to the skin-associated bacteria of the individual who touched the object. Here we describe a series of studies de-monstrating the validity of this approach. We show that skin-associated bacteria can be readily recovered from surfaces (including single computer keys and computer mice) and that the structure of these communities can be used to differentiate objects handled by different individuals, even if those objects have been left untouched for up to 2 weeks at room temperature. Furthermore, we demonstrate that we can use a high-throughput pyrosequencing-based ap-proach to quantitatively compare the bacterial communities on objects and skin to match the object to the individual with a high degree of certainty. Although additional work is needed to further establish the utility of this approach, this series of studies introduces a forensics approach that could eventually be used to independently evaluate results obtained using more traditional forensic practices.


More on the work here.

May 31, 2010 at 02:01 PM | Permalink


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