Antibacterials affecting cell membrane

Polymyxins

Daptomycin

Polymyxin B & E

Cyclic peptides with hydrophobic tail

(+) charged free amino group that act as cationic detergents, disrupts phospholipid structure of membrane

Bind to membrane, cause openings, so it is leaky

Selectively toxic for gram (-) bacteria, attracted to (-) charge phosphate on lipopolysaccharide

Neurotoxic & Nephrotoxic , used as a last option

Typically used for Pseudomonas Aeruginosa or Carbapenemase- producing Enterobacteriaceae

Not absorbed by GIT

Used in infantile diarrhea

Externally used for eye infection/ otitis external (swimmers ear)

Less effective on gram (+) unless given with other agents like trimethoprim

Lipopeptide antibiotic

Used in treatment of systemic/ life threatening infection from gram (+) bacteria

Disrupts many aspects of cell membrane function

Aggregates in cell membrane, alters it’s curvature, creates holes that leak ions

Leads to rapid depolarization, cell death

Not orally absorbed

Cannot penetrate membrane of gram (-) bacteria

Treatment of skin/ skin structure infections by gram (+), S. Aureus & endocarditis

Unique spectrum # MRSA & Vancomycin- resistant E. Faecalis/ E. Faecium (VRE)

Inactivated by pulmonary surfactants, cannot be used in pneumonia