New study could help fight bacterial infections without antibiotics

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Researchers at the Mohali Institute of Nanoscience and Technology have found a new way to treat drug-resistant bacterial infections – by inducing bacteria to self-destruct

When the bacteria were exposed to an alternating magnetic field, there was a rapid rise in temperature, high enough to destroy them | Representative image: iStock

Although many powerful antibiotics are available on the market, our indiscriminate use has rendered them useless in the treatment of several common bacterial infections. Bacteria have mutated and developed clever techniques to combat the effect of drugs. Scientists are now actively researching alternative methods to combat drug-resistant bacterial strains, one of them being the nanotechnology-based approach.

Researchers from the Institute of Nanoscience and Technology (INST) in Mohali have found a new way to treat drug-resistant bacterial infections: by inducing the bacteria to self-destruct.

A chance discovery

This new method of treatment was born from a discovery they came across. They discovered that certain highly infectious bacteria synthesize magnetic nanoparticles in their cells. “Taking advantage of this property, we agitated the nanoparticles with an alternating magnetic field to generate hyperthermia (excess heat) in the bacteria,” said Professor Deepa Ghosh, lead researcher of the study. India science thread. The results of the study indicate that the induced heat destroyed 70-80% of the bacteria, thus reducing the infection.

Also Read: How Scientists Propose to Fight Drug Resistant Bacteria, Ditch the Antibiotics

Just like humans and other animals, bacteria also need iron and zinc for their growth and development. Infectious bacteria are fed by the host body. The host’s immune system prevents invading bacteria from accessing these metals through “nutritional immunity”, i.e. by binding these metals to specific proteins or storing them in specialized compartments so that bacteria cannot access these metals.

However, infection-causing bacteria have developed strategies to acquire these metals from other sources in the body. For example, they release proteins called siderophores that attach to hemoglobin in our blood, scavenge iron from hemoglobin, and store excess metals for future use.

Professor Ghosh’s team studied several virulent drug-resistant bacterial strains such as S. aureus, E. coli, P. aeruginosa, A. baumannii, K. pneumoniae, to name a few, obtained from infected patients. During their lab experiments, they were surprised to find that these bacteria stored iron and zinc in tiny 10-20 nanometer magnetic particles inside their cell, which was previously unknown.

“Such biosynthesis of magnetic nanoparticles is only seen in aquatic bacteria called magnetotactic bacteria, which they use as a magnetic compass to navigate the waters,” Professor Ghosh said.

Further experiments concluded that the infectious bacteria nanoparticles were zinc ferrites with magnetic properties and were attracted to an external magnet.

Using an external magnetic field

From their previous research on cancer cells, Professor Ghosh’s team observed that cancer cells also form magnetic nanoparticles from zinc and iron. These cancer cells could be destroyed by inducing hyperthermia by exposing the cells to an external alternating magnetic field.

“We wanted to see if we could induce a similar response in bacteria by agitating their internally synthesized nanoparticles,” Prof Ghosh said.

They characterized the bacterial nanoparticles and confirmed their magnetic properties using state-of-the-art instruments. When the bacteria were exposed to an alternating magnetic field, they observed a rapid rise in temperature, which confirmed that the nanoparticles could produce heat. The external magnetic field moved the nanoparticles back and forth following the external alternating magnetic field, creating a loss of energy that dissipated as heat. The heat raised the temperature of the surrounding environment by nearly 4 to 5 degrees centigrade. “When translated into the microenvironment of bacterial cells, the temperature rise is high enough to destroy them,” Professor Ghosh explained.

Also Read: Pathogens Kill People and Antibiotics Don’t Help

Encouraged by the results, the team repeated their experiments with clinical samples of infected tissue containing bacteria known to be resistant to next-generation antibiotics such as ciprofloxacin, cefotaxime, amikacin, imipenem and meropenem. They exposed the infected tissue to 30 minutes of a 347 kHz magnetic field (a harmless range for humans). They found that it induces enough heat to kill 70-80% of bacteria.

Open new paths

The favorable result supported their findings that the bacteria in the samples exhibited significant sensitivity to the magnetic field. “Our study opens new avenues for treating bacterial infections without antibiotics,” Professor Ghosh said. The team is stepping up research to treat bone infections where deeper penetration of the magnetic field is needed. For now, they have patented their method and are exploring prototypes to treat diabetic foot wounds.

The team consisted of Swati Kaushik, Jijo Thomas, Vineeta Panwar, Preethi Murugesan, Vianni Chopra, Navita Salaria, Rupali Singh, Himadri Shekar Roy, Rajesh Kumar, Vikas Gautam and Deepa Ghosh. The results were published in the journal At the nanoscale.

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