Final answer:
Antimicrobial agents that work against the cell membrane are called inhibitors of membrane function, with polymyxin B and polymyxin E (colistin) being examples that lack selective toxicity, hence their limited systemic use.
Step-by-step explanation:
Antimicrobial agents that work against the cell membrane are known as inhibitors of membrane function. The polymyxins, particularly polymyxin B and polymyxin E (colistin), are examples of substances that target the bacterial membrane.
These agents are lipophilic and have detergent-like properties that disrupt both the outer and inner membranes of gram-negative bacteria, resulting in cell death. However, these drugs are not selectively toxic and can also damage kidney and nerve cells, limiting their systemic use.
Instead, polymyxin B is found in some over-the-counter topical ointments, and colistin was historically used for bowel decontamination. The emergence of multidrug-resistant bacteria has impacted the usage of these agents.