Meningitis Vaccine May Work Against Gonorrhea

Most news about gonorrhea gets worse each passing day.

The World Health Organization (WHO) says 77 countries are showing antibiotic resistance is making gonorrhea – a common sexually-transmitted infection – much harder, and sometimes impossible, to treat.

The WHO reports some countries – particularly high-income ones, where surveillance is best – are finding gonorrhea cases untreatable by all known antibiotics.

The current recommended regimen for gonorrhea is a combination of two antibiotics azithromycin and ceftriaxone.

"These cases may just be the tip of the iceberg, since systems to diagnose and report untreatable infections are lacking in lower-income countries where gonorrhea is actually more common," adds Dr. Teodora Wi, Medical Officer, Human Reproduction, at WHO.

But, there is some potentially good news, from an unrelated vaccine.

A new study suggests a meningitis vaccine may also ward off the gonorrhea infection.

This is the first time a vaccine has shown any protection against gonorrhea.

This research reported the gonorrhea rate among people who had received a MeNZB vaccine in the early 2000s was significantly lower than those who were not vaccinated.

The estimate vaccine effectiveness of MeNZB against gonorrhea after adjustment for ethnicity, deprivation, geographical area, and sex was 31 percent in this study.

But, it's difficult to form any conclusions because of the nature of the case and control groups.

This conclusion is an ‘association’, not a direct ‘cause-effect.’

This was a retrospective case-control study of patients at sexual health clinics aged 15-30 years who were born between Jan 1, 1984, and Dec 31, 1998, eligible to receive MeNZB, and diagnosed with gonorrhea or chlamydia, or both. There were 14,730 cases and controls for analyses. Vaccinated individuals were significantly less likely to be cases than controls (41% vs 51%).

These results provide a proof of principle that can inform prospective vaccine development not only for gonorrhea but also for meningococcal vaccines, said these researchers.

Gonorrhea and meningitis are quite different from one another, but the bacteria that cause Neisseria gonorrhoeae and Neisseria meningitidis are actually related, said these researchers.

There are vaccines for several Neisseria meningitidis strains, but designing a vaccine to protect against the B strain was difficult. As a consequence, the vaccine component that was made to protect against B targets a different part of the bacterium.

That may explain why the B vaccine appears to offer some protection against gonorrhea.

Study co-author Thomas Naderer, PhD, Biomedicine Discovery Institute and Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia, said in a statement released with the findings that he and his team hope that their new understanding of the mechanism of gonorrhea “may lead to strategies to combat [the disease] and its symptoms.”

Using cutting-edge super-resolution microscopy, the researchers found that these membrane vesicles interacted with the cells in the human immune system called 'macrophages', triggering these to die in an orchestrated suicide process.

Macrophages are the cells within the immune system that ordinarily kill foreign invaders like bacteria and viruses, so without them, the gonorrhea bacteria can flourish.

Dr. Naderer said "That this new understanding of how the gonorrhea bacteria interact and cause the death of immune system cells "may lead to strategies to combat gonorrhea infection and its symptoms".

The research may also provide information as to how other bacteria evade the immune system and be unaffected by antibiotics.

The study was supported by the National Health and Medical Research Council, Canberra, Australia with a project grant (1024839, TN) and program grant (606788, GD and TJL). TN is an Australian Research Council Future Fellow. The funders had no role in study design, data collection, and analysis, decision to publish, or preparation of the manuscript.