How can normal flora become virulent?

Normal flora can become virulent through several mechanisms, including genetic mutations that enhance their pathogenicity, the acquisition of virulence factors via horizontal gene transfer, or changes in the host's immune status that allow these microorganisms to overgrow and cause infection. Environmental factors, such as antibiotic use or disruption of the microbiome, can also shift the balance, allowing normally benign organisms to become opportunistic pathogens. Additionally, when normal flora enter sterile areas of the body, such as through injury or surgical procedures, they can lead to infections.