Monday, July 1, 2013

Hype Watch July 1

The Facts: A nanoscale cantilever device can detect differential responses of bound bacteria to antibiotics through changes in oscillation frequency.

The Hype: "Thanks to this method, it is quick and easy to determine if a bacteria has been effectively treated by an antibiotic.... Easily used in clinics..." Science Daily

The Reality: Development of rapid diagnostics for ID/AST (identification/antibiotic susceptibility testing) is not being held back by a lack of awesome biosensor technologies. Those are as common as warts on a witch. It's the pre-analytic steps that are the problem. The indications for which rapid ID/AST are really needed either have vanishingly low levels of bacteria (bloodstream infections) or samples in which pathogens are mixed with commensals (pneumonia).

The nano-cantilever offers no obvious innovation in bacterial ID. Although it detected a signal from just a few hundred bacteria, the sample applied held 10e5 cells, presumably at a high concentration, 10e7/ml or more. Since most positive bacteremia samples have less than 1 bacterial cell per mL, there is a 7 log gap in current vs needed sensitivity.

The verdict: if the pre-analytic problem can be solved and a method of rapid ID can be coupled to it, then nano-cantilevers could potentially give AST results in minutes, rather than hours or days. That's a pretty big "if".

 

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