How Nanoparticles Kill Drug-Resistant Bacteria
Multidrug-resistant pathogens are causing researchers to focus on developing new agents with strong therapeutic potency. The lengthy list of drug-resistant pathogens includes the penicillin-resistant Streptococcus pneumonia, the extensively drug-resistant Mycobacterium tuberculosis, which a quarter of the world has, and MRSA, a bacteria that is the paramount cause of nosocomial (hospital originating) infections associated with pneumonia, bloodstream infections, and surgical site infections. Metal nanoparticles have shown to be effective agents against drug-resistant pathogens. Scientists have synthesized them from algae, actinomycetes, bacteria, plants, sugar, biodegradable polymers, and many more substrates.
The stem bark extract of Murraya koenigii, a small aromatic tree, called the curry tree contains alkaloids and derivatives that have potent antibacterial activity on many pathogens. It’s green leaves have been used in the Indian medicinal system and have shown anti-hyperglycemic effects on rats under diabetic conditions. In addition, a lab study has shown that the plant’s antioxidant and anti-inflammatory abilities are comparable to today’s standard drugs.
Two scientists from India and two from Saudi Arabia collaborated and reported in Hindawi the use of the curry tree’s leaves to synthesize silver nanoparticles in the laboratory. They picked the leaves from a nearby area and prepared them by washing, drying, grinding, hydrating, heating, centrifuging, and filtering them. Next, they combined the leaves’ extract with silver nitrate solution, producing a nanoparticle with 60.86% silver, and tested it on gram-positive and gram-negative bacterial strains.
They learned that Murraya koenigii Silver Nanoparticles (MK-AgNPs) attacked the bacteria’s respiratory chain, it’s cell division, and released silver ions inside of it; ultimately leading to the cells death. The MK-AgNps were found to be an effective antibacterial agent against both gram-positive and gram-negative test bacteria with varying sized zones of inhibition. MRSA required 32 micrograms per milliliter, E.Coli needed up to 64 micrograms per milliliter, while the control strain, which was not drug-resistant, only needed 16 micrograms per milliliter.
Silver nitrate by itself didn’t work because it didn’t have sufficient surface area to make sufficient surface contact with the pathogens, while the nanoparticles did. The synergistic properties between metal and natural compounds are also required to kill these kinds of bacteria. This could be the solution to the evolution of superbugs. And pharmaceutical companies looking to make a drug to combat these types of bacteria may be exploring this possibility after more careful investigation with the use of live subjects.
