What do polymyxins and colistin primarily affect in bacterial cells?

Polymyxins and colistin primarily target the cell membrane function of bacterial cells. These antibiotics are particularly effective against Gram-negative bacteria, as their action disrupts the integrity of the bacterial cell membrane. Polymyxins interact with the lipopolysaccharides and phospholipids found in the outer membrane of these bacteria, leading to increased membrane permeability. This disruption results in leakage of cellular contents, ultimately causing cell death.

Understanding the mechanism of action of polymyxins is important in the context of antibiotic resistance and treatment of multidrug-resistant infections, particularly those caused by Gram-negative pathogens. In contrast, other options do not accurately reflect the primary mechanism of action of polymyxins and colistin. For instance, cell wall integrity and nucleotide synthesis are affected by different classes of antibiotics, such as penicillins and fluoroquinolones, respectively. Similarly, protein synthesis inhibitors target ribosomal function rather than membrane integrity. Therefore, recognizing that polymyxins and colistin specifically compromise cell membrane function is crucial for comprehending their role in antibacterial therapy.