Study reveals new potential antibiotic for resistant gonorrhoea

Recently, there has been much in the news about gonorrhoea and its resistance to available drugs, giving rise to calls for urgent action to be taken to combat this rapidly spreading sexually transmitted disease. As such, researchers from London have evaluated a new class of antibiotic, closthioamide (CTA), as a potential treatment, finding that it has high anti-gonococcal activity in vitro.

In this study, published in the journal Antimicrobial Agents and Chemotherapy, the team examined 149 clinical and eight World Health Organisation (WHO) Neisseria gonorrhoeae isolates. Additionally, they looked at four commensal strains that had been provided by Barts Health NHS Trust, St George’s University Hospitals NHS Foundation Trust, Royal Free NHS Foundation Trust and Tunbridge Wells NHS Trust hospital laboratories.

CTA was discovered in 2010 and was isolated from Clostridium cellulolyticum, which is an anaerobic bacterium. It is a new class of antibiotics formed from natural polythioamide and has been shown to have antimicrobial activity although its molecular mechanism is suggested to be different to that of quinolones and aminocoumarins.

The results from this study demonstrated that CTA inhibited the growth of the majority (98%) of clinical gonococcal strains examined at a low therapeutic dose. Further, isolates resistant to the current first-line therapeutic options were found to be susceptible to CTA, indicating its potential as a treatment for multidrug resistant strains of gonorrhoea. However, the researchers noted that further studies are required.

In a recent news report from The Guardian lead author from the London School of Hygiene and Tropical Medicine, Victoria Miari, said: “The results of our initial laboratory studies show that closthioamide has the potential to combat N. gonorrhoeae. Further research is needed, but its potential to successfully tackle this infection, as well as other bacteria, cannot be underestimated.”

“There is a long way to go from where we are right now before we have a medicine ready to give to anyone in the clinic,” added Dr John Heap, lead author from Imperial College London’s department of life sciences, in the same report. “Often you might come across an antibiotic and it looks just like all the other antibiotics — it is a very close relative of an existing one or it turns out it does just the same thing. [Closthioamide] is exciting, partly because it has such a weird structure we might expect it to have different properties to other antibiotics.

“Fortunately, in the case of this [antibiotic], there is a method to make it synthetically so we don’t have to grow massive, massive vats of the bacteria and squeeze tiny amounts out.”