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As proof of principle, Weissleder and Lee demonstrated they could detect a bacterium very similar to tuberculosis in sputum samples. First, the viscous sample must be liquefied. Then it's mixed with a solution of cannonball-shaped iron nanoparticles coated in antibodies that stick to the bacteria. The sample is loaded onto the detector, which uses microfluidics to force the sample through a channel fitted with a screen that traps bacteria and washes free any nanoparticles that didn't meet a target. This channel is surrounded by a metal coil that pulses the trapped bacteria with radio-frequency waves under the influence of a magnet. This causes the iron nanoparticles to emit a magnetic signal, in turn affecting the protons in the surrounding water molecules. The Harvard device picks up on these changes, whose magnitude and duration are directly proportional to the number of labeled bacteria in the sample.
The bacteria detection process takes about 30 minutes and is as sensitive as processes that use culture samples grown in the lab. The results are described in the journal Angewandte Chemie.
"Trying to diagnose very low levels of bacteria in a sample while maintaining high quality is not an easy thing to do," says pathologist Miller. The Harvard test is very sensitive--that is, it can detect low levels of bacteria--but until the device undergoes more tests, it's impossible to say how specific it is. If it proves to have high rates of false positives, says Miller, it won't be viable in places like the United States, where tuberculosis rates are low. However, says Miller, "there could be a lot of value for a cheap and easy test like this in areas with high tuberculosis prevalence."
The researchers are collaborating with the Harvard School of Public Health to test the device on clinical samples from patients carrying tuberculosis.
A startup has developed a device that uses magnetic particles to identify pathogens rapidly.
Inaccurate dosing may be a culprit in the evolution of drug-resistant strains.
A cheap smart-phone microscope could bring fluorescent medical imaging to areas with limited access to health care.
Manufacturing in the United States is in trouble. That's bad news not just for the country's economy but for the future of innovation.
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340 Comments
Ingenious
We had an employee in a large dept at previous company I worked at who was found to have TB so they had to test everyone.
The health dept worker who came in to tell us was clueless. The person was telling me you have the bacteria for life (probably based on positive skin test after exposure even w/o disease).
I seriously doubt this and think they were told to say this, as it is easier to tell the public.
Bacteria can be killed much easier than viruses (not being alive) so the bacteria can be either minimized or totally gone. Plus if you have had it you'll have the immune response molecules present from your immune system's memory which can last well beyond any infection. And the skin test is not for the bacteria but for the antibodies.
Once you HAVE been exposed, e.g. our med class teacher was in ward with TB pt, she has to get periodic x-rays to confirm not have it as already tests positive by skin test. this would be much better.
That combine with the mentioned shortcomings of the test make this much better.
This technique likely has the potential to be modified to detect other bacteria before they trigger immune responses (which vary and may not happen). Maybe viruses too.
We do PCR amplification now for gonorrhea and chlamydia, which can detect similar minute amounts. but this is not something dr office will do inhouse. our lab has specialized gear.
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