Antibiotic resistance genes are commonly transferred between bacteria via:
Vertical inheritance through binary fission faithfully copies the single circular chromosomal DNA with high fidelity via DNA polymerase III holoenzyme but fails to explain extraordinarily rapid global dissemination of antibiotic resistance observed within decades of antibiotic introduction. Horizontal gene transfer provides direct mechanism for movement of accessory genes between genetically unrelated cells, even across genus barriers. Conjugation involves direct cell-to-cell contact via retractile sex pilus encoded by tra operon and transfer of conjugative plasmids and integrative conjugative
Ref: Alberts et al., Molecular Biology of the Cell, 7th ed., Chapter 5: Horizontal Gene Transfer and Resistance Spread.
