Antimicrobial susceptibility testing (AST) is critical in modern medicine, helping doctors determine which antibiotics are most likely to be effective against particular bacterial infections. Across the globe, standards for AST primarily revolve around the European EUCAST and the American CLSI. Dr. Gunnar Kahlmeter, one of the main architects of EUCAST, offers unique insights into the past, present, and future of AST.
About Dr. Kahlmeter
Dr. Kahlmeter has been at the forefront of clinical microbiology since 1971. Over his illustrious career, he has led several clinical microbiology laboratories, presided over the European Society of Clinical Microbiology and Infectious Diseases (ESCMID), and chaired the European Committee on Antimicrobial Susceptibility Testing (EUCAST) for 12 years. Even at the age of 73, his enthusiasm remains undiminished.
EUCAST’s Global Impact
The EUCAST system, co-developed by Kahlmeter, is now a global standard, including in countries like China. The system tests bacteria for susceptibility against a range of drugs. Dr. Kahlmeter’s contributions have been recognized worldwide, leading to collaborations and discussions in various countries, including China.
Methods of Antimicrobial Susceptibility Testing
AST is conducted primarily through two methods:
1. MIC (Minimal Inhibitory Concentration) Testing with Broth Microdilution: This method gauges the lowest concentration of an antibiotic that can inhibit bacterial growth.
2. Disk Diffusion: Here, paper disks soaked with antibiotics are used to measure inhibition zones to determine bacterial resistance or susceptibility.
The Role and Misuse of MIC
While MIC can be invaluable in unclear cases, offering definitive answers, it is not always necessary. Kahlmeter emphasized the significance of determining if a bacterium belongs to the “wild-type” distribution against various agents. If a bacterium belongs to the wild-type, then there’s no need for an MIC, as it doesn’t possess resistance mechanisms.
Summary
The world of antimicrobial susceptibility testing has seen substantial advancements, much credit to visionaries like Dr. Kahlmeter. As antibiotic resistance continues to pose challenges, the expertise and systems developed by institutions like EUCAST remain vital in guiding medical decisions. It’s essential to understand and appropriately use methods like MIC testing while recognizing their limitations to ensure effective patient care.
Dr. Gunnar Kahlmeter
Head of the National Reference Laboratory on Phenotypic Susceptibility Testing of Bacteria
