Biosensing Platform Detects Bacterial Pneumonia

A technique has been developed that will diagnose and differentiate the organisms that cause pneumonia using nanotechnology.

The method combined the existing technology of surface-enhanced Raman spectroscopy (SERS) with silver nanorods to identify different strains of Mycoplasma pneumoniae. Raman spectroscopy works by detecting spectral signatures of a near-infrared laser as it scatters off a biological specimen.

Scientists at the University of Georgia (UGA; Athens, GA, USA), were able to detect and differentiate M. pneumoniae strains from throat swabs. They equated the nanorod array system to a brush with densely packed bristles, where each of the tiny silver rods extends out at a specific angle. The sample, such as bacteria from a throat swab, penetrates among the bristles, where the spectral signature produced by the laser is amplified and then analyzed by a computer program.

Clinical throat swab samples, collected from the University of Alabama (Birmingham, AL, USA), were processed by extraction and subsequently tested by polymerase chain reaction (PCR). Three M. pneumoniae strains were reproducibly differentiated by nanorod-SERS (NA-SERS), with 95%–100% specificity and 94%–100% sensitivity, and with a lower detection limit exceeding standard PCR. In addition, NA-SERS correctly classified with greater than 97% accuracy, 10 true clinical throat swab samples previously established by real-time PCR and culture to be positive or negative for M. pneumoniae.

Duncan C. Krause, PhD, a professor of microbiology at UGA, said, "If you can make a positive identification from a 10-minute test, then appropriate antibiotics can be prescribed, limiting both the consequences in that patient and the likelihood that it will spread to others. The device can be reduced to a size that could fit in a briefcase, although testing is currently done only in a laboratory setting. Our hope is that when we begin to explore the capabilities of this technology, it can be applied in point-of-care testing. Then the impact becomes truly significant."

Infections due to M. pneumoniae are very common yet difficult to diagnose. The bacterium is a major cause of respiratory disease in humans accounting for 20% of all community-acquired pneumonia and the leading cause of pneumonia in older children and young adults. It can cause permanent damage to the lungs if not diagnosed promptly. A delay in diagnosis extends the likelihood for complications as well as continued transmission to the community. The study was published online December 2010 in PLoS One.

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University of Georgia
University of Alabama