Scientists use gold to weaken defenses of antibiotic-resistant bacteria
Bacteria resistant to standard antibiotic treatments can be killed by drugs specially formulated with gold packaging, according to an international team of scientists from the University of Leeds, UK, and Chinese universities: the Southern University of Science and Technology in Shenzhen and Fudan University, Shanghai. The scientists have developed gold nanoparticles that retain their antimicrobial properties without harming healthy host mammalian cells.
Exploiting the concept of opposing forces of attraction in nature, the gold nanoclusters are wrapped in a molecule called a ligand that is positively charged. It then finds and delivers the nanoclusters to the wall of negativelycharged bacteria cells; it also disrupts the bacterial cell membrane.
The disruption to the cell membrane increases the permeability of the bacterial cell to standard antibiotic treatments.
In addition to the opposing charges, the scientists included a second ligand – zwitterionic groups – to protect host cells from toxicity. These molecules have both positive and negative charges which makes the gold nanoclusters more compatible with host mammalian cells, and easier for the gold nanoclusters to pass through the kidney and be excreted from the body.
In laboratory tests, it was observed that antibiotics used in combination with the gold nanoclusters showed an improved antimicrobial effect – there was a 128-fold decrease in the amount of antibiotic needed to inhibit growth of methicillin resistant Staphylococcus epidermidis (MRSE), the bacterial strain used in the tests. MRSE is responsible for some notorious hospital acquired infections.
“By systematically tuning the ratio of the two ligands, we have identified a way of using gold nanoclusters not only to act as effective antimicrobial agents, but as a mechanism to enhance the potency of antibiotics which have become ineffective because of bacterial drug resistance,” said Dejian Zhou, Professor at Nanochemistry at the University of Leeds.
Professor Zhou believes combing gold nanoclusters with existing antibiotics will be a faster and cheaper alternative to developing a host of new antibiotics in response to bacterial antibiotic resistance.
Read: New virus-antibiotic combination therapy fights antibiotic-resistant bacteria
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