Cell Membrane Labilizer Part 1

Cell membrane labilizers

Antibacterial agents that disrupt bacterial cell membrane integrity.

Main antibacterial class discussed in this module

Polymyxins.

Polymyxins

Class of polypeptide antibiotics that disrupt bacterial cell membranes.

Source of polymyxins

Bacillus polymyxa.

Polymyxins are classified as

Polypeptide antibiotics.

Structure of polymyxins

Seven amino acids arranged in a cyclic configuration.

Polymyxins isolated historically

Polymyxins A, B, C, D, E, and M.

Clinically important polymyxins

Polymyxin B and Polymyxin E.

Another name for Polymyxin E

Colistin.

Source of colistin

Bacillus colistinus.

Polymyxin B and colistin are commonly used as

Sulfate salts.

Primary target of polymyxins

Bacterial cell membrane.

Major effect of polymyxins

Disruption of bacterial cell membrane function.

Polymyxins are

Bactericidal.

Why polymyxins are bactericidal

They cause membrane damage leading to bacterial cell death.

Polymyxins alter

Osmotic pressure and membrane permeability.

Polymyxins affect

Selective permeability and regulatory functions of the membrane.

Unique property of polymyxins

Detergent-like action on bacterial membranes.

Polymyxins can be combined with bacteriostatic drugs

Yes.

Reason polymyxins can be combined with bacteriostatic drugs

Their activity does not require rapid bacterial multiplication.

Additional effect of polymyxins

Anti-endotoxin activity.

Another additional effect of polymyxins

Antipyretic activity.

Why polymyxins have anti-endotoxin effects

They bind negatively charged endotoxins.

Polymyxins are basic drugs

Cationic drugs.

Endotoxins are

Anionic molecules.

Major bacterial group targeted by polymyxins

Gram-negative bacteria.

Polymyxins have what spectrum of activity?

Narrow spectrum.

Main veterinary importance of polymyxins

Treatment of Gram-negative infections.

Most common polymyxins used in veterinary medicine

Polymyxin B and colistin.

Main mechanism category of polymyxins

Cell membrane disruption.

Polymyxins differ from beta-lactams because

They act on the cell membrane rather than the cell wall.

Polymyxins are not considered protein synthesis inhibitors

True.

Polymyxins are not considered cell wall inhibitors

True.

Polymyxins belong to which antimicrobial target category?

Cell membrane inhibitors.

Major clinical application of polymyxins

Gram-negative enteric infections.

Polymyxins are commonly used for

E. coli infections.

Polymyxins are commonly used for

Salmonella infections.

Polymyxins are useful in

Pseudomonas infections.

Colistin belongs to which antimicrobial class?

Polymyxins.

Polymyxin B belongs to which antimicrobial class?

Polymyxins.

Cell membrane integrity is essential for

Maintaining bacterial survival.

Loss of membrane integrity results in

Bacterial death.

Detergent-like action means

Disruption of membrane structure and function.

Polymyxins are considered last-line drugs in some resistant Gram-negative infections

True.

Most important module focus regarding polymyxins

Mechanism, spectrum, pharmacokinetics, and toxicities.

High-yield association

Polymyxins = Cell membrane disruption.

High-yield association

Polymyxin B = Membrane labilizer.

High-yield association

Colistin = Polymyxin E.

High-yield association

Bacillus polymyxa = Source of polymyxins.

High-yield association

Gram-negative bacteria = Main target.

High-yield association

Narrow spectrum = Polymyxins.

High-yield association

Anti-endotoxin activity = Polymyxins.

High-yield association

Bactericidal = Polymyxins.

High-yield association

Detergent-like action = Polymyxins.

High-yield association

Cell membrane target = Polymyxins.

Mnemonic for polymyxins

P = Punches holes in membranes.

Mnemonic for colistin

C = Cell membrane crusher.

Most important characteristic of polymyxins

Disrupt bacterial cell membranes causing rapid bacterial death.