12 Testing for resistance mechanisms in your workplace

You have now learned about some of the more clinically important mechanisms of antimicrobial resistance and how to test for them.

Activity 14

Timing: Allow 10 minutes

Based on your existing knowledge and what you have learned in this module, what are the issues and challenges to bear in mind when performing tests to identify the resistance mechanism of isolates? When might you need to send an isolate to the reference laboratory for additional testing?

Make notes in the text box and then compare with the example answer.

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Discussion

Some issues and challenges when identifying resistance mechanisms are listed below, but you may have thought of others:

  • being aware of the most important/widespread pathogen-AMR combinations in your setting
  • knowing which resistance mechanism is most likely for a given pathogen-resistance combination
  • using the most appropriate screening method
  • using the most appropriate confirmatory method
  • understanding the principle behind common phenotypic and genotypic tests so that you are better able to recognise potential errors and anomalies
  • recognising the complexity of the screening and confirmatory testing processes
  • recognising that some resistance mechanisms can mask or enhance other mechanisms, e.g. AmpC and ESBL in Enterobacterales; permeability and efflux pumps in Pseudomonas
  • ensuring you have training in and access to SOPs for all tests you perform
  • knowing when isolates should be referred to reference laboratories for confirmatory testing. This might be if for example you cannot identify it accurately to species level, your tests of mechanism do not give you a clear answer, it is the first time you have come across this pathogen-resistance combination in your laboratory or the resistance profile is unusual for this species.

As long as your laboratory is identifying the species and mechanisms accurately, you can be confident that you are providing reliable data for surveillance. You will then be making an important contribution to fighting antimicrobial resistance both locally and around the world.

11 Importance of quality control

13 End-of-module quiz