Developing a test that can be used to detect antimicrobial resistance in samples from gonorrhoea patients

🧪 What was the study about?

The Gonococcal Resistance to Antimicrobial Surveillance Programme (GRASP) looks at antimicrobial resistance to gonorrhoea treatment. Resistance is where antimicrobial treatment is not as effective or does not work. The programme monitors resistance by growing the gonorrhoea bacteria from patient samples using a laboratory method called culturing. Once the bacteria have been grown, they can be tested for antimicrobial resistance to help decide what treatment is best to use. However, the bacteria do not grow in about half of patient samples so antimicrobial resistance of the bacteria in those samples are unknown. We want to use a different method called PCR to look at antimicrobial resistance, when culturing does not work.

❓ Why is this important?

It is important to know which treatments will be effective when someone is diagnosed with gonorrhoea. This means that they can be given the most effective treatments as soon as possible, reducing the chance of harm from untreated gonorrhoea and treatment failure. Use of the PCR method will help to give a clearer picture of how resistant gonorrhoea is spreading, which can help inform treatment guidelines.

🔍 What did we do?

We used a laboratory method called PCR on samples from people diagnosed with gonorrhoea, to see if it was effective at detecting antimicrobial resistance to an antibiotic called ceftriaxone. This method is a molecular test that does not need us to grow (culture) the bacteria from the sample. We also used the method on samples from people diagnosed with gonorrhoea in 2020 to see if there is any resistance to ceftriaxone in those samples.

📊 Key findings

The PCR method successfully identified all samples that had resistance to ceftriaxone and most samples were confirmed positive for gonorrhoea. It did not mistakenly detect other, similar bacteria. No resistance to ceftriaxone was found in the samples from 2020.

💡 What do these findings mean?

These findings have shown that we can use PCR to successfully detect resistance to ceftriaxone in patient samples. This method can be used to identify gonorrhoea infections that are resistant to ceftriaxone more quickly, and to recommend the most effective treatments for gonorrhoea. We can also use this method to look at how resistant gonorrhoea might be spreading when we cannot grow the bacteria.

The PCR method has since been used to test samples from people diagnosed with gonorrhoea between 2023 and 2024 to look for ceftriaxone resistance. This was prompted by a small group of related resistant cases found in England in 2022, to see if the resistant strain had spread. Only one case was found which was already known, meaning that no unexpected resistant cases were detected. This suggests that UKHSA’s current surveillance is working well to monitor ceftriaxone resistance. Please follow the link for more detail:  https://doi.org/10.1136/sextrans-2024-056459