Determining antimicrobial susceptibility and antimicrobial resistance mechanisms in the clinical laboratory: where are we and where are we heading?

Since the discovery of penicillin, almost a century ago, the battle against resistant microbes has been fierce but uneven. Microbes have been proven quite adaptable and have developed many different antimicrobial resistance (AMR) mechanisms to evade antibiotics. These AMR mechanisms mainly regulate cephalosporin and carbapenem resistance for Gram-negative bacteria, methicillin resistance for Staphylococcus aureus and vancomycin resistance for Enterococci. Greece is endemic for most known multi-drug resistant organisms (MDRO) that often cause community and hospital-acquired infections, perplexing treatment, increasing length of stay in the hospital and relevant costs, and increasing morbidity and mortality. Detection and treatment of such infections in a timely and effective way is imperative. For the past few decades, scientists from different scientific fields have been developing technologies and methods to assist the early and reliable detection of AMR to optimize not only treatment but also infection control practices in an effort to restrain it. This review focuses on current practices to detect AMR and the corresponding resistance mechanisms. From the well-established classic diffusion antibiogram to the rapid automated tools that provide susceptibility profiles of bacteria within a few hours, and from the time-consuming phenotypic AMR detection methods to rapid molecular AMR mechanism detection directly from the sample, Microbiology has come a long way. Most microbiological laboratories are currently using a combination of phenotypic and molecular methods for AMR detection, in an effort to make the best out of both. Integrating novel technologies into the laboratory routine workflow has its challenges, with the financial burden being one of the most significant. However, if the progress in the field of Microbiology since the emergence of the first resistant microbe until now is any indication, the future holds many more adventures and scientific breakthroughs in the fight against AMR.