When symbiotic gut flora populations are disrupted (e.g., by antibiotics), one becomes more vulnerable to pathogens. The rapid evolution of antibiotic resistance places an enormous selective pressure on the advantageous alleles of resistance passed down to future generations.
The disruption of symbiotic gut flora populations, such as those caused by antibiotics, increases susceptibility to infections. This vulnerability is driven by the rapid evolution of antibiotic-resistant bacteria, which favors the inheritance of resistance genes.