IISc study finds way to identify bacterial power

BENGALURU: Researchers from the Indian Institute of Science (IISc) have found a way to develop a bed-side, table-top device for quick diagnosis of bacterial infection and treat it using optimal antibiotic treatment while avoiding antibiotic resistance in the bacteria.

The method is a unique one in which Raman microspectroscopy -- otherwise used to identify chemical bonds in materials -- is used to rapidly identify and check whether a disease-causing bacterium is alive or dead, and if alive, how strong or weak it is, based on which the precise dose of antibiotics can be prescribed.  

Identifying bacterial viability helps deciding the precise dose of antibiotics to be prescribed, and reduce the possibility of over-prescription leading to antibiotic resistance, an IISc release said. Quick detection of the disease-causing bacteria, as well as checking whether it is alive or not in patient samples are key for treatment.  

“The uniqueness of this study is the rapidity and sensitivity of the method, and its potential for being modified into a bed-side, table top device for diagnosis,” Srividya Kumar, a former PhD student in the Department of Inorganic and Physical Chemistry, and first author of the study published in the journal Analytical and Bioanalytical Chemistry, said.

Infectious bacteria are usually identified by techniques like culturing, taking up to three days to track their growth and confirm whether they are dead or alive. Besides, bacteria difficult to grow in lab cultures often go undetected by conventional methods. And the more sophisticated Polymerase Chain Reaction (PCR), while capable of creating genetic profiles of microbes, cannot tell whether they are alive or dead. But the new method provides a quick solution.

The researchers used this technique to detect whether tuberculosis bacterium (Mycobacterium tuberculosis) was present in a sample.Using a microspectroscope, the researchers bounced a laser beam off the sample and captured the light scattered by the sample in the form of a spectrum, which varies with the biochemical composition of the bacterium. Each bacterial species generates a unique spectrum with specific values for intensity and wavelength position of the scattered light, depending on the type of chemical bonds present inside the bacterial cell.

Using this method, the researchers were not only able to identify the bacterium but were also able to differentiate between living and dead bacterial cells -- as chemical composition of the two differs -- within just 2-3 hours after sample collection, IISc said.

“Though we have validated the method for TB, the methodology can be extended to any type of bacterial infection,” said Deepak Saini, Associate Professor in the Department of Molecular Reproduction, Development and Genetics, IISc, and one of the senior authors of the study.