Resistant strains develop primarily through two mechanisms: mutation and horizontal gene transfer. Mutations occur randomly and can sometimes confer an advantage in the presence of antimicrobial agents. Horizontal gene transfer involves the acquisition of resistance genes from other microorganisms through processes like conjugation, transformation, or transduction. Factors such as overuse and misuse of antibiotics, inadequate infection control practices, and agricultural use of antimicrobials further accelerate the development of resistant strains.
