Role of rapid diagnostics in reducing antimicrobial resistance

November 10 2015

 Last year a  review of antimicrobial resistance  was commissioned by The UK prime minister to address the global human and economic burden of drug resistance over the next 35 years.  The first 3 papers entitled " Tackling a Crisis for the Health and Wealth of Nations" "Tackling a Global Health Crisis: Initial Steps"  & "Securing New Drugs for Future Generations" were published between Dec 14 and May 15.
The 4th paper on the role of rapid diagnostics in tackling resistance has just been published.(Rapid diagnostics -stopping unnecessary use of antibiotics :Review on Antimicrobial Resistance chaired by Jim O'neill)

 Since any use of antibiotics encourages resistance it is vital to limit their unnecessary use to extend their functionality and to ensure the right patients get treated effectively. Antimicrobial resistance is a global problem that needs a global solution - drug resistant infections travel and do not stop at borders.

Because of a lack of rapid diagnostics the world vastly overuses antibiotics in both rich and poor countries. One study in the US suggests that around 27 million antibiotic courses were wasted on patients who did not need them in one country alone and for only one type of  illness - respiratory disease. Antimicrobial stewardship can improve the prescribing habits and the expectations of patients - and will partially address overuse. There is a high correlation between antibiotic use and resistance. This document largely tackles  antibiotic use - but a parallel situation exists for antifungal medicines with a growing  emergence of  antifungal drug  resistance occurring in both the clinic and the environment (link).  Notably clinical  azole-resistant A. fumigatus isolates are also cross-resistant to five triazole fungicides used as pesticides agriculturally (link). 

Testing for antifungal sensitivity of an isolate by measuring the MIC  (minimum inhibitory concentration) 

The widespread availability of rapid diagnostics would reduce unnecessary prescribing of antimicrobials and antifungals. Without rapid diagnostics at the point of care it is hard for a clinician to give the right drugs.
We may  have the ability to diagnose an infection rapidly in a clinic - for example  there are rapid tests for gonorrhoea infection - but the lack of a  rapid test for its drug susceptibility - means that valuable antibiotic (or antifungal)  resources are wasted by using the drug to which fewest strains are resistant.

The paper indicates that the  "perfect" new rapid diagnostic test should  inform  a diagnosis and a treatment with the correct drug  before any medicines are given to the patient - in a matter of minutes not the current 36 - 48 h. A rapid test should identify 1. the source of infection - bacterial, viral or fungal; 2. What type of bacteria/fungi is involved; 3. Is it resistant to a particular drug, and 4. To which drugs is the infectious agent susceptible.

Rapid diagnostic improvements for fungal infections have more than one  important part to play, both in the reduction of drug resistance and in improving human health as a whole.

Fungal lung infections, for example, can often be misdiagnosed as TB, leading to unnecessary treatment with often toxic antibiotics. The ineffective antibiotic treatment may continue for as long as two years, when a simple anti-fungal might have worked. Fungal blood infections such as Candida spp. and invasive candidiasis are often misdiagnosed as bacterial infections, leading to the unnecessary prescription of antibiotics. This puts selection pressure on bacteria in the gut and increases resistance. With rapid diagnostics, clinicians can give the right drugs to the right patients more quickly, reducing the number of unnecessary antibiotic prescriptions and improving outcomes for infections such as Candida.

The paper describes three specific policy interventions with the aim of accelerating practical innovation in the area of rapid diagnostics  over a 2- 5 year period  (view  Article).