Bacterial cell membrane

The mechanism of action of quats has been widely studied. It is generally agreed that their iateraction with the bacterial cell membrane is the primary event resulting ia antimicrobial activity (16,17). 

Polyethers. Antibiotics within this family contain a number of cycHc ether and ketal units and have a carboxyHc acid group. They form complexes with mono- and divalent cations that ate soluble ia aoapolar organic solvents. They iateract with bacterial cell membranes and allow cations to pass through the membranes causiag cell death. Because of this property they have been classified as ionophores. Monensia, lasalocid, and maduramicia are examples of polyethers that are used commercially as anticoccidial agents ia poultry and as growth promotants ia mmiaants. 

In the absence of an AGAC the ribosomes will prodnce the artificial polypeptides, polyphenylalanine (as specified by the codon UUU) or polyproline (as specified by the codon CCC). However, when streptomycin is added, the ribosomes prodnce a mixture of polythreonine (codon ACU) and poly serine (codon UCU). The misreading of the codons does not appear to be random U is read as A or C and C is read as A or U. If such misreading occurs in whole cells the accumulation of non-functional or toxic proteins would eventually prove fatal to the cells. There is some evidence that the bacterial cell membrane is damaged when the cells attempt to excrete the faulty proteins. 

Polymyxins are a group of antibiotics which disrupt bacterial cell membranes. Two mechanisms of acquired resistance to the polymyxins have been identified (Russell Chopra 1996). 

Daptomycin (15 Cubicin ) Daptomycin (15) Lipopeptide NP Microbial Antibacterial Disrupts multiple aspects of bacterial cell membrane function 211-225... 

Daptomycin 1980 Lipo peptide Bacterial Cell Membrane... 

Bacitracin (Fig. 4) is a cyclic peptide antibiotic. The lipid II molecule involved in the bacterial cell wall biosynthesis has a C55 isoprenyl pyrophosphate moiety that must be dephosphorylated so that it can reparticipate in another round of lipid II transfer. Bacitracin binds to the isoprenyl pyrophosphate and prevents the dephosphorylation which, in turn, blocks cell wall growth by interfering with the release of the muropeptide subunits to the outside of the bacterial cell membrane. Bacitracin inhibits similar reactions in eukaryotic cells. So, it is systemically toxic but is an effective and widely used topical antibiotic. 

A novel cyclic lipopeptide antibiotic was isolated from cultures of Strep-tomyces roseosporus grown in the presence of decanioc acid. Daptomycin interacts with the bacterial cell membrane and interferes with membrane potential.Unlike polymyxin B, daptomycin can target majority of clinically relevant Gram-positive pathogens. 

The main component of bacterial cell membranes is a mixed polymer known as murein or peptidoglycan. Peptidoglycan is a long polysaccharide chain that is cross-linked with short peptides. 

The synthesis of peptidoglycan of bacterial cell membranes can be divided into three stages based on where the reaction takes place. 

Thus, beta-lactam antibiotics can inihibit the process of synthesis of bacterial cell membranes in different ways, thus causing them to die quickly. 

Bacitracin is a bactericidal drug that inhibits the formation of linear peptidoglycan chains, which are the main component of bacterial cell membranes. Most Gram-positive bacteria,... 

Pharmacology Vancomycin is a tricyclic glycopeptide antibiotic that inhibits cell-wall biosynthesis. It also alters bacterial-cell-membrane permeability and RNA synthesis. Pharmacokinetics ... 

Mechanism of Action A second-generation cephalosporin that binds to bacterial cell membranes and inhibits cell wall synthesis. Therapeutic Effect Bactericidal. Pharmacokinetics Well absorbed from the GI tract. Protein binding 25%. Widely distributed. Primarily excreted unchanged in urine. Moderately removed by hemodialysis. Half-life 0.6-0.9 hr (increased in impaired renal function). 

Mechanism of Action A first-generation cephalosporin that binds to bacterial cell membranes and inhibits cell wall synthesis. Therapeutic Effect Bactericidal. 

Mecftantsm of Action A third-generation cephalosporin that binds to bacterial cell membranes. Therapeutic Effect Inhibits synthesis of bacterial cell wall. Bactericidal. Pharmacokinetics Widely distributed, including cerebrospinal fluid (CSF). Protein binding 82%-93%. Metabolized and excreted in kidney and urine. Removed by hemodialysis. Half-life 1.6-2.4 hr (half-life is increased with impaired renal function). 

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