Colistin

Definition

Colistin is a polymyxin antibiotic used as a last-resort treatment for multidrug-resistant Gram-negative bacterial infections. It disrupts the bacterial cell membrane, leading to cell death.

5 Must Know Facts For Your Next Test

1. Colistin targets the lipopolysaccharide (LPS) layer of Gram-negative bacteria.
2. It is often reserved for treating infections caused by bacteria resistant to other antibiotics due to its nephrotoxicity and neurotoxicity.
3. Colistin's mechanism of action involves binding to the LPS in the outer membrane of Gram-negative bacteria, disrupting membrane integrity.
4. Resistance to colistin can occur through modifications in the bacterial LPS structure, often mediated by the mcr-1 gene.
5. Testing for colistin effectiveness typically involves broth microdilution methods due to its unique pharmacodynamics.

Review Questions

• What is the primary mechanism of action for colistin?
• Why is colistin considered a last-resort antibiotic?
• Describe how resistance to colistin can develop in bacteria.

Related terms

Polymyxin B:

Another member of the polymyxin class used to treat Gram-negative bacterial infections.

Nephrotoxicity: The toxic effect that some substances, including certain antibiotics like colistin, have on the kidneys.

mcr-1 gene: A plasmid-mediated gene that confers resistance to colistin by altering the LPS structure in bacteria.