Page 108 - MNU-PM502- Pharmaeutical Microbiology Theoritical Book

Pharm D- Clinical Pharmacy Program Third Level Pharmaceutical Microbiology& Antimicrobials (PM 502)

Cell membrane inhibitors

Glycopeptides: Daptomycin

Spectrum:
• active against Gram-positive including highly resistant strains such as
MRSA
• NOT active against Gram-negative pathogen G+ve bacteria

➢ Used in the treatment of systemic and life-threatening infections (S. aureus
bacteremia, S. aureus endocarditis)

➢ Has poor activity in the lungs and should not be used to treat
pneumonia.

Polymyxins: Colistin

Colistin is known as polymyxin E

• a cationic cyclic decapeptide with a fatty acid side chain

Mechanism: Altering membrane permeability

• The positive charge allows colistin to
bind to the negatively charged

lipopolysaccharide molecules in the
bacterial outer membrane, displacing
+2
+2
Ca and Mg ions that normally
stabilize these lipids.

• The fatty acid tail facilitates further
insertion of colistin into the outer

membrane leading to increased
permeability and, eventually, lysis of
the bacterium

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