Aquarius Population Health

Aquarius Population Health recently worked with the Applied Diagnostic Research & Evaluation Unit (ADREU) at St. Georges, University of London, to assess the cost-effectiveness of six hypothetical strategies for using antimicrobial resistance point-of-care testing to guide the treatment of gonorrhoea.  Our findings were presented at the STI & HIV World Congress in Rio de Janeiro, Brazil. [Wednesday 12th July, Session 15: STI/HIV testing and management].

The development of antimicrobial resistance to gonorrhoea is a global concern. In England, gonorrhoea is the third most commonly diagnosed sexually transmitted infection. Based on guidelines, the first line recommended drug therapy changes if more than 5% of strains tested demonstrate resistance. Previously, single drug therapy was effective. The most recent change in first line treatment was in 2011, when a combination of two drugs, ceftriaxone and azithromycin were recommended. By using a combination of two drugs, the chance of antimicrobial resistance developing is reduced. Although this combination remains an effective treatment for most gonorrhoeal infections, there have been a small number of multi-drug resistant cases which cannot be treated with ceftriaxone. If resistance to ceftriaxone spreads, there are no obvious alternatives.

One possible way to preserve the usefulness of ceftriaxone is to minimise its use. This can be done by only using it for infections which could not be treated using the older abandoned antibiotics. This would require each infection to be quickly assessed for antimicrobial resistance using a point-of-care test. Antimicrobial point-of-care testing is already being used in other fields such as TB, but is not yet routinely used in sexual health clinics. We assessed the cost-effectiveness of six possible strategies for using antimicrobial resistance point-of-care testing to guide the treatment of diagnosed gonorrhoea.

As we anticipated, all the antimicrobial point-of-care testing strategies cost more than the standard care – which does not involve any resistance testing before treatment is given. The most cost-effective strategy relative to standard care was a dual antimicrobial point-of-care test for azithromycin and ciprofloxacin resistance where the therapy was either ceftriaxone and azithromycin (i.e. standard treatment), if there was no resistance to azithromycin; ciprofloxacin and ceftriaxone, if there was resistance to azithromycin; or ceftriaxone, if there was resistance to both. This strategy also provided the most optimal treatments overall.

A resistance point-of-care test for azithromycin followed by azithromycin monotherapy if no resistance was present was the strategy that resulted in the most ceftriaxone treatments avoided.

This work provides some key insight into the benefits and costs of antimicrobial resistance testing within sexual health clinics and is one of many antimicrobial resistance projects we have been involved in. If you would like to find out how Aquarius Population Health could work with you, please contact us.

Dr Susie Huntington