Efflux pumps and their role in antibiotic resistance: A literature review

Background: Antibiotic resistance is a mounting global health crisis, with bacterial efflux pumps identified as a key mechanism driving this threat. These membrane-bound transport proteins actively expel a wide range of antibiotics and toxic compounds from bacterial cells, reducing intracellular drug concentrations and enabling survival during treatment. This literature review aims to explore the molecular mechanisms, structural classifications, and clinical significance of efflux pumps in mediating multidrug resistance (MDR). Five major efflux pump families—Resistance-Nodulation-Division (RND), Major Facilitator Superfamily (MFS), Small Multidrug Resistance (SMR), Multidrug and Toxic Efflux (MATE), and ATP-Binding Cassette (ABC) transporters—are examined in detail, along with their energy sources, substrate specificities, and roles in both Gram-negative and Gram-positive bacteria. Findings highlight that efflux pumps not only confer direct antibiotic resistance but also enable the development of additional resistance mechanisms. The review further discusses emerging therapeutic strategies, particularly efflux pump inhibitors (EPIs), which hold potential for restoring antibiotic efficacy. Understanding the complex biology and regulation of efflux systems is crucial for combating MDR and guiding the development of innovative antimicrobial interventions.