Inoculum standardisation device for the EUCAST disk-diffusion method

In the clinical microbiology laboratory, antibiotic susceptibility testing (AST) is most often carried out in order to determine which antibiotics can be used to treat specific bacterial infections. It helps to assure susceptibility to drugs of choice for known bacteria and can detect possible drug resistance development in commonly encountered pathogens.¹

The laboratory AST procedure is extremely important for individual patients, but on a much wider scale it has become essential due to recent rapid developments of antimicrobial resistance. In terms of antibiotic stewardship, AST is an extremely important part of the treatment selection process.² According to the World Health Organization, new resistance mechanisms are constantly emerging and pose increasingly serious threats to global public health. Without effective antimicrobial therapies, it is believed that many routine medical interventions will fail or become extremely dangerous to perform in the future. Currently, 700,000 people die of antimicrobial- resistant infections every year, and by 2050 this is predicted to rise to 10 million. It is also estimated that US$100 trillion could be lost due to the rise in drug-resistant infections.³ With huge potential public health and global financial pressures being threatened, the magnitude of the resistance problem is now beginning to be accepted and tackled.³

The most commonly used method in UK laboratories was the British Society for Antimicrobial Chemotherapy (BSAC) technique; however, the BSAC is ceasing active support of its method, and laboratories are being encouraged to move to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) disk-diffusion technique. All differences between the two methods to aid transition can be found in the BSAC Difference between BSAC-EUCAST methods document,⁴ as outlined in Table 1.