Antibiotics are commonly used to treat infections and ensure the safety of surgical procedures. However, their overuse has led to the emergence and spread of resistant bacteria, resulting in an “arms race” whereby ever more potent drugs are becoming a necessity. As antimicrobial resistance represents an ever-growing healthcare challenge worldwide, researchers from the Systems Ecology research group at the Luxembourg Center for Systems Biomedicine (LCSB) and the Department of Life Sciences (DLSM) and from the Molecular Disease Mechanisms group at DLSM explored the impact of antibiotic treatment on the microbial community inhabiting the gut of mice. Their results, recently published in Nature Communications, highlight that some bacteria are more likely to acquire antimicrobial resistance genes than others. The researchers also describe the key mechanisms involved in the short-term evolution of antibiotic resistance within the gut microbiome.