Antibiotic resistance and virulence: Understanding the link and its consequences for prophylaxis and therapy.

"Antibiotic resistance is usually associated with a fitness cost" is frequently accepted as common knowledge in the field of infectious diseases. However, with the advances in high-throughput DNA sequencing that allows for a comprehensive analysis of bacterial pathogenesis at the genome scale, including antibiotic resistance genes, it appears that this paradigm might not be as solid as previously thought. Recent studies indicate that antibiotic resistance is able to enhance bacterial fitness in vivo with a concomitant increase in virulence during infections. As a consequence, strategies to minimize antibiotic resistance turn out to be not as simple as initially believed. Indeed, decreased antibiotic use may not be sufficient to let susceptible strains outcompete the resistant ones. Here, we put in perspective these findings and review alternative approaches, such as preventive and therapeutic anti-bacterial immunotherapies that have the potential to by-pass the classic antibiotics.