Tree compound can kill drug-resistant bacteria

Hydroquinine is an organic compound, closely related to quinine, that has proven anti-malarial and anti-arrhythmia properties. It occurs naturally in the bark of some tree species and has been the focus of attention by researchers recently because they thought it may have the potential to fight against antibiotic resistant bacteria. The phenomenon of multi-drug resistant microbes has become a global health burden in the past few decades, and there is a pressing need for the development of new antimicrobial drugs to combat infections.

When bacteria are exposed to an antibiotic multiple times, new strains of the bacteria evolve that are resistant to the drug. This means that the resistant bacteria are no longer controlled or killed by the antibiotics. In fact, they survive and are even able to multiply in the presence of an antibiotic to which they have developed resistance. As a consequence of this, the treatment of bacterial infections has become more complex and less effective. Researchers are constantly searching for new types of antimicrobial drugs to take the place of those that no longer work against the resistant strains.

Scientists from the University of Portsmouth and the Naresuan and Pibulsongkram Rajabhat Universities in Thailand have now investigated whether hydroquinine is effective at inhibiting the growth or reproduction of eight different strains of bacteria, including Streptococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae and Enterobacter cloacae. These pathogens are commonly resistant to multiple drugs and cause infections in patients with burn wounds, cystic fibrosis, skin lesions and pneumonia, both in hospital settings and in communities. Although hydroquinine is a tried and tested remedy against malaria, its antibacterial properties have not yet been determined.

In the findings of this research, published in the journal Tropical Medicine and Infectious Disease, the scientists show that hydroquinine inhibited all the strains of bacteria tested, and even killed them if the concentration of the compound was high enough.  

“Using bacterial killing experiments, we found that hydroquinine was able to kill several microorganisms, including the common multidrug-resistant pathogen Pseudomonas aeruginosa,” said Dr. Robert Baldock from the School of Pharmacy and Biomedical Sciences at the University of Portsmouth.

“Characteristically, we also discovered that one of the main mechanisms used by these bacteria to escape killing activity of the drug was upregulated with treatment – indicating a robust response from the bacteria.”

“By studying this compound further, our hope is that it may in future offer another line of treatment in combatting bacterial infections,” he added. 

Drug-resistant bacteria occur in more than 2.8 million infections and are responsible for 35,000 deaths per year. Common antibiotic-resistant “superbugs” cause diseases including sepsis, urinary tract infections, and pneumonia. Statistics show bloodstream infections by the bacterium P. aeruginosa can be associated with high mortality rates of between 30 and 50 percent. 

The experts conclude that hydroquinine has antibacterial properties and can inhibit and kill several strains of clinically important bacteria. However, the researchers emphasize that further research is necessary in order to understand the mechanism by which the compound acts in order to have the observed effect on the pathogens. They also recommend that future studies address the potential side effects of using hydroquinine. 

Dr Jirapas Jongjitwimol from the Department of Medical Technology at Naresuan University added: “Our future research aims to uncover the molecular target of hydroquinine. This would help our understanding of how the compound works against pathogenic bacteria and how it could potentially be used in a clinical setting.”

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By Alison Bosman, Earth.com Staff Writer