How can incomplete or improper antibiotic use encourage drug-resistant bacteria?

Incomplete or improper use of antibiotics encourages the development of drug-resistant bacteria by creating selective pressure within bacterial populations.12

When an antibiotic is used, it typically kills the most sensitive bacteria. However, if the dosage is insufficient or the treatment regimen is not completed, some bacteria that are genetically less vulnerable may survive. Because their more sensitive competitors have been eliminated or reduced, these resistant survivors face less competition for resources, allowing them to proliferate and multiply.324

Furthermore, these surviving bacteria can transfer their resistance to other organisms through gene exchange, such as conjugation or transduction. This process can lead to the rapid spread of resistance across different bacterial species, eventually resulting in infections that are untreatable by standard medications. Consequently, completing a full prescribed regimen is a critical ethical and medical responsibility to prevent the emergence of these dangerous, resistant strains.3124