Preparation of cumulative antibiograms that describe local bacterial susceptibility patterns is an essential requirement for sensible empirical antibiotic prescribing and guideline development. Over coming weeks, I will share learnings from Australia where all hospitals are compiling antibiograms that are in accord with the CLSI M39-A2 Guideline and an Australian format for standardised antibiograms that is based on M39.
Some important over-riding issues include:
- Selection of specimen results that are reliable – exclusion of mixed cultures and likely contaminants
- Assessment of the quality of antimicrobial susceptibility testing – see this brief question guide.
- Exclusion of repeat same species isolates samples from the same person within a one year interval
- Correct selection of the antibiotics that are tested (as per CLSI or EUCAST current guidelines) and reported in the antibiogram
- Expression of % susceptible rather than % resistant with the number tested displayed against each antibiotic
- Exclusion of species where < 30 isolates have been tested
- Eventual stratification of specimens by whether they have a community versus healthcare-associated origin