BENGALURU: Indian scientists working in a Harvard lab have developed a screening test to detect molecules that may be effective against drug-resistant bacteria.
Dr Rajmohan Rajamuthiah and Dr Elamparithi Jayamani, post-doctoral research fellows at Harvard Medical School in Boston, have already tested their screening system on deadly drug-resistant bacteria like MRSA and acinetobacter baumannii. They hope to apply it on klebsiella pneumoniae, another drug-resistant bacterium, soon. Dr Rajamuthaiah says, “Drug discovery and development are expensive, costing up to $1 billion to bring the drugs from the lab to the patient. As traditional methods of antibiotic drug discovery have become expensive and unattractive, new strategies are urgently needed.”
He said their test method can be used to efficiently screen thousands of chemicals. It can also be adapted to the simple laboratory working conditions in Indian schools and college labs.
How the System Works
Their test works on the principle that bacteria harmful to humans are also harmful to C. elegans, a 1-mm long non-pathogenic, non-parasitic organism that lives in the soil. Antimicrobial compounds that can cure bacterial infections in humans have a similar protective effect on C. elegans.
In the past, many research groups have used C. elegans to test for environmental toxicity, which makes C. elegans too sick, much the way it affects human beings.
The two scientists incubated C. elegans in petri dishes with the potential antimicrobial compounds and bacteria. This would cause the worms to die either because of infection or because the compounds are toxic. The dead worms are then tested further.
Dr Rajamuthaiah says, “Our system allows us to test compounds and simultaneously assess both antibacterial activity and toxicity. So, it will streamline and prioritise the most promising compounds for further testing. This will save us time and money.”
According to him, the biggest advantage of the system is that it can identify compounds that have immunomodulatory properties, that is, they don’t directly affect the bacteria but boost one’s immune system to fight the infection.
Dr Rajamuthaiah says their system could be the ideal platform to test traditional Indian medicines as well. “India has a vast repository of traditional medicines which have not been fully explored. Traditional medicines might hold the key to treating bacterial infections because many of them boost immunity,” he says.
Staphylococcus aureus and A. baumannii are normally harmless bacteria, but are capable of harming humans when they enter the body tissues through breaches or cuts on the skin. They can cause infection in the skin, lungs and bones.
Major Drug-Resistant Bacteria
Staphylococcal strains can circumvent the human body’s defence mechanisms and several strains have also become resistant to antibiotics such as methicillin (MRSA), making S. aureus the leading cause of hospital-acquired infections, which lead to thousands of fatalities every year.
A. baumannii, popularly called the ‘Iraqi Bacteria’, is surprisingly efficient in developing drug-resistance. It was responsible for causing deadly infections in American soldiers wounded in Iraq and Afghanistan. Studies show that A. baumannii infections typically have a 50 per cent fatality rate.
Klebsiella pneumonia strain is another emerging drug-resistant bacteria in South Asia.