South Africa’s plant species key to the discovery of novel antibiotic against WHO-identified ‘critical’ drug-resistant pathogen – MUT study found

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21 March 2023

South Africa’s plant species key to the discovery of novel antibiotic against WHO-identified ‘critical’ drug-resistant pathogen – MUT study found


In its 2017 response to the scourge of drug-resistant pathogenic infections, the World Health Organization (WHO) identified a list of pathogens that it described as critical, high and medium priority in terms of the urgency of the need for novel antibiotics. The Pseudomonas aeruginosa (P. aeruginosa) bacteria were named among the three bacterial strains that WHO classified as a critical research priority.

A recent study by MUT researchers found that the South African plant species could hold the potent key to the discovery of novel antibiotics against the drug-resistant P. aeruginosa bacteria.

P. aeruginosa is an opportunistic pathogen that commonly infects individuals who are immune compromised, particularly those infected with the human immunodeficiency virus (HIV) and/or those suffering from cancer. It is a common etiological agent of hospital-acquired pneumonia, urinary tract infections and bacteremia,” explained the study.

The study was conducted by MUT’s Dr McMaster Vambe, Postdoctoral Researcher; Professor Roger Coopoosamy, Acting Dean of the Faculty of Natural Sciences; Professor Kuben Naidoo, Acting Head of the Department of Nature Conservation; and Professor Georgina Arthur, whom until her recent retirement was a member of staff in the Department of Nature Conservation.

Titled, ‘South African medicinal plants screened against Pseudomonas aeruginosa’, the study was published in the Journal of Medicinal Plants for Economic Development.

In its review of ethnobotanical studies relating to the pathogen, the study found that only 31 were published over two decades and none of these studies was dedicated solely to P. aeruginosa. Another startling finding was that none of the studies on the pathogen was published in the first three years after the WHO classified it as a critical research priority.

The study, which evaluated various studies that screened plants against the pathogen, found that a total of 152 plant species were screened against the bacterium using crude plant extracts.

“It was encouraging to note that almost half of all plant species evaluated demonstrated noteworthy antibacterial activities against the pathogen,” the study explained.

In terms of phytochemical analysis, the study singled out a study which identified and isolated a compound called plumbagin from the leaves of Asteraceae.

“Interestingly, the compound displayed potent bactericidal effects against P. aeruginosa. To the best of our knowledge, this was the only successful attempt at isolating potent anti-P. aeruginosa from South African medicinal plants documented over the past 20 years,” the study confirmed.

The study also reviewed research that was conducted on the feasibility of using plants in combination therapy to combat P. aeruginosa. The study explained that combination therapies were important because they “widen the antibacterial spectrum, improve the efficacy of clinically ineffective drugs and generally delay the development of antibiotic resistance”.

Several reviewed studies that tested combination therapies where South African medicinal plant extracts interacted with conventional antibiotics against P. aeruginosa generated promising results. The study concluded that these combination therapies could be the quickest and cheapest way to fight the P. aeruginosa pathogen.

“The use of drug-resistance modifying agents in combination therapies could potentially improve the efficacy and hence allow the possible reintroduction of some clinically ineffective antibiotics. From a financial point of view, this approach seems more appealing than developing novel therapeutic agents which customarily have to undergo extensive efficacy and safety evaluations before approval,” the study advised.


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