Drug resistance, also referred to as antimicrobial resistance, occurs when infection-causing bacteria, viruses, parasites, or fungi evolve to resist a drug that once destroyed them.
Sadly, such a scenario is becoming increasingly common. In the United States alone, there are at least 2 million drug-resistant infections every year, and more than 23,000 people die from these infections.
Drug-resistant tuberculosis (TB) is deemed a "serious" threat by the Centers for Disease Control and Prevention (CDC). Worldwide, multidrug-resistant TB — which is TB that is resistant to the two strongest anti-TB drugs — affects more than 480,000 people annually.
Needless to say, winning the fight against drug-resistant TB would represent a huge leap forward in the fight against drug resistance as a whole.
Dr. Sanjib Bhakta — of the Institute of Structural and Molecular Biology at Birkbeck, University of London, United Kingdom — and colleagues believe their new study could make a big contribution; the team has identified a number of onion-derived compounds that can kill TB bacteria.
'Nature is an amazingly creative chemist'
The compounds come from Allium stipitatum, also referred to as the Persian shallot, which is a type of onion commonly used in Iranian cooking. It is also known for its antibacterial properties, a feature that caught the attention of Dr. Bhakta and team.
For their study, the researchers enhanced these antibacterial properties by synthesizing various compounds present in the bulb of the Persian shallot.
They then tested the effects of these synthesized compounds on various drug-resistant bacteria, including Mycobacterium tuberculosis, which is the bacterial species that causes TB.
The team found that the compounds showed inhibitory effects against Escherichia coli, multidrug-resistant Staphylococcus aureus, Klebsiella pneumoniae, and Proteus mirabilis.
The most promising synthesized compound, however, was found to inhibit the growth of M. tuberculosis by 99.9 percent.
Based on these results, Dr. Bhakta — who co-led the study — and colleagues suggest that onion-derived compounds may help to combat drug-resistant infections.
"In searching for new antibacterials, we tend to focus on molecules that are potent enough to be developed commercially as new drug entities by themselves. However, in this study we show that by inhibiting the key intrinsic resistance properties of the TB, one could increase the effects of existing antibiotic treatment and reverse the tide of already existing drug resistance."
Dr. Sanjib Bhakta
"Natural products from plants and microbes have enormous potential as a source of new antibiotics," adds study co-leader Prof. Simon Gibbons, of University College London in the United Kingdom. "Nature is an amazingly creative chemist and it is likely that plants such as the Persian shallot produce these chemicals as a defense against microbes in their environment."
In future research, the team hopes to identify more natural compounds that could help tackle drug-resistant bacteria.