Untreatable gonorrhoea superbugs are resistant to antibiotics – new research on a MenB vaccine could help scientists find a solution
The dire warnings about antimicrobial resistance (AMR) are becoming a reality: some strains of the bacteria that cause gonorrhoea are untreatable. The WHO says 78 million people are infected with gonorrhoea every year and called for more research on new treatments.
The search for new antibiotics and gonorrhoea vaccines have proven hugely challenging. However, new research published in The Lancet Infectious Diseases, suggests a new avenue for vaccine development.
The paper looks at the impact of vaccination with the outer membrane vesicle (OMV) meningococcal B vaccine (MeNZB) on the likelihood of contracting gonorrhoea. The New Zealand study of more than 14,000 people compared gonorrhoea rates in those who had received the MeNZB vaccine to those who had not.
It found that those who had been vaccinated with MeNZB were less likely to develop gonorrhoea.
“This new research could be game-changing and merits further investigation,” said Linda Glennie, Head of Research at Meningitis Research Foundation, a patient group not involved in the study. “It could ultimately add weight to the argument for vaccinating teenagers with the MenB vaccine, especially since gonorrhoea has become increasingly resistant to antibiotics”.
Why would a MenB vaccine prevent gonorrhoea?
Despite the two diseases being very different in terms of symptoms and mode of transmission, there is an 80-90% genetic match between the Neisseria gonorrhoeae and Neisseria meningitidis bacteria, providing a biologically plausible mechanism for cross-protection.
Previous data suggested already a decline in gonorrhoea in the period immediately after use of group B meningococcal outer membrane vesicle (OMV) vaccines in Cuba, New Zealand and, to some extent, Norway.
In New Zealand, approximately 1 million individuals (81% of the population under 20 years) received the MeNZB vaccine, during a mass immunisation programme in 2004-2006, providing a unique opportunity to test the cross-protection hypothesis.
Researchers found that vaccinated individuals were significantly less likely to have gonorrhoea than controls (41% vs 51%). Taking into account all other factors such as ethnicity, deprivation, geographical area, and gender, the researchers conclude that having previously received the MeNZB vaccine reduced the incidence of gonorrhoea by approximately 31%.
“Our findings provide experimental evidence and a proof of principle that an OMV meningococcal group B vaccine could offer moderate cross-protection against gonorrhoea,” says Dr Helen Petousis-Harris, University of Auckland, New Zealand, and lead author of the study. “This is the first time a vaccine has shown any protection against gonorrhoea. At the moment, the mechanism behind this immune response is unknown, but our findings could inform future vaccine development for both the meningococcal and gonorrhoea vaccines.”
The authors note that because of the variability of different strains of N. gonorrhoeae and N. meningitidis bacteria, the effect of the vaccine might vary depending on the strain. And being co-infected with chlamydia slightly reduced the effectiveness of the vaccine.
Co-author of the study, Professor Steven Black, Cincinnati Children’s Hospital, USA, adds: “The potential ability of an OMV group B meningococcal vaccine to provide even moderate protection against gonorrhoea would have substantial public health benefits in view of the prevalence of gonorrhoea, and the increase in antibiotic resistance. If the 4CMenB vaccines, which are currently available, are shown to have a similar effect to the MeNZB vaccine, then administering it in adolescent immunisation programmes could result in declines in gonorrhoea.”
Experts not involved in the study say this new finding offers hope in the fight against a major global public health challenge. Professor Christopher Fairley, Melbourne Sexual Health Centre, Carlton, Australia, said sexually-transmitted infections remain a neglected issue globally. “Ultimately, the development of vaccines against both extensively drug resistant gonorrhoea as well as chlamydia are likely to be the only sustainable solutions to control these infections,” he said.