Antimicrobials mechanisms of action

Hamouda, T., and Baker, J. R., Antimicrobial mechanism of action of surfactant lipid preparations... 

This chapter emphasized palmitic acid, its physical, chemical and structural features as pertaining to its functional characteristics, occrtrrence and percent distribution in plants, algae, fimgus, human and animal tissues. The antimicrobial mechanisms of action, metabolism, general biochemisby and health implications of palmitic acid provide insight into the versatile... 

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). 

Other Nitrogen Compounds. The basis of the sophisticated nitrogen compounds Hsted in Table 10 is the reaction of formaldehyde with amino compounds. A significant amount of Hterature details investigation of the mechanism of action, particularly whether or not the antimicrobial activity depends on decomposition to formaldehyde (40—42). These compounds tend to have substantial water solubiUty and are more effective against bacteria than fungi and yeasts. Key markets for these compounds are metalworking fluids, cosmetics, and in-can preservation of paints (see Alkanolamines Amines, fatty amines). 

Thiostrepton family members are biosynthesized by extensive modification of simple peptides. Thus, from amino acid iacorporation studies, the somewhat smaller (mol wt 1200) nosiheptide, which contains five thiazole rings, a trisubstituted iadole, and a trisubstituted pyridine, is speculated to arise from a simple dodecapeptide. This work shows that the thiazole moieties arise from the condensation of serine with cysteiae (159,160). Only a few reports on the biosynthesis of the thiostrepton family are available (159,160). Thiostrepton is presently used ia the United States only as a poly antimicrobial vetetinary ointment (Panalog, Squibb), but thiazole antibiotics have, ia the past, been used as feed additives ia various parts of the world. General (158) and mechanism of action (152) reviews on thiostrepton are available. 

Hooper DC(2001) Mechanism of action of antimicrobials focus on fluoroquinolones. Clin Infect Dis 32 (Suppl 1) S9-S15... 

Additional hypotheses for their mechanism of action have more recently been proposed. It is well known that proanthocyanidins are able to complex metals through their ortho-diphenol groups. This property is often viewed as imparting negative traits (e.g., reduction of the bioavailability of essential mineral micronutrients, especially iron and zinc) [87]. Since iron depletion causes severe limitation to microbial growth, their ability to bind iron has been suggested as one of the possible mechanisms explaining the antimicrobial activity of proanthocyanidins [88] (Table 1). 

Epand RM, Vogel FIJ (1999) Diversity of antimicrobial peptides and their mechanisms of action. BBA-Biomembranes 1462 11-28... 

Antimicrobial Other Agent(s) Mechanism of Action/Effect Clinical Management... 

Antimicrobials, including antibiotics, are drugs used to destroy or slow the growth of microorganisms in our body. The mechanisms of action of these drugs on the microbes can be classified as follow ... 

The recent elucidation of the immunomodulatory activities of host defense peptides is perhaps the most intriguing to the development of these molecules as therapeutics. Importantly, many peptides that have been demonstrated to be devoid of antimicrobial activity under physiological conditions have maintenance of immunomodulatory activities. That host defense peptides have also recently been demonstrated to bridge innate and adaptive immune responses and as well act as adjuvants extends their therapeutic potential beyond the resolution of infection. Recent investigations have also sought to define the cell receptors involved in the immunomodulatory activities of host defense peptides in an effort to define the mechanism of action of these molecules and further the understanding of how these molecules are able to elicit such a broad range of... 

Antimicrobial agents can be subdivided according to their mechanism of action, by their general structure or by their indications. For a systematic presentation of the various agents mostly some compromise between the three is found. In this text the structural relationships are the principal guidelines for their classification. 

Although all tetracyclines have a similar mechanism of action, they have different chemical structures and are produced by different species of Streptomyces. In addition, structural analogues of these compounds have been synthesized to improve pharmacokinetic properties and antimicrobial activity. While several biological processes in the bacterial cells are modified by the tetracyclines, their primary mode of action is inhibition of protein synthesis. Tetracyclines bind to the SOS ribosome and thereby prevent the binding of aminoacyl transfer RNA (tRNA) to the A site (acceptor site) on the 50S ri-bosomal unit. The tetracyclines affect both eukaryotic and prokaryotic cells but are selectively toxic for bacteria, because they readily penetrate microbial membranes and accumulate in the cytoplasm through an energy-dependent tetracycline transport system that is absent from mammalian cells. 

Mechanism of Action An antinauseant and antiulcer agent that absorbs water and toxins in the large intestine and forms a protective coating in the intestinal mucosa. Also possesses antisecretory and antimicrobial effects. Therapeutic Effect Prevents diarrhea. Helps treat Helicobacter pybri-associated peptic ulcer disease. 

Mecfianism of Action A cyclic polypeptide antimicrobial but the mechanism of action is not well understood. Therapeutic Effect Suppresses mycobacterial multiplication. Pharmacokinetics Not well absorbed from the GI tract. Undergoes little metabolism. Primarily excreted unchanged in urine. Haif-iife 4-6 hr (half-life is increased with impaired renal function). 

Mechanism of Action A biologic response modifier that induces activation of macrophages in blood monocytes to phagocytes, which is necessary in the body s cellular immune response to intracellular and extracellular pathogens. Enhances phagocytic function and antimicrobial activity of monocytes Therapeutic Effect Decreases signs and symptoms of serious infections in chronic granulomatous disease. Pharmacokinetics Slowly absorbed after subcutaneous administration. Half-life 0.5-1 hr. 

Mechanism of Action An antitubercular that inhibits DNA-dependent RNA polymerase, an enzyme in susceptible strains of Escherichia coli and Bacillus subtilis. Rifabutin has a broad spectrum of antimicrobial activity including against mycobacteria such as Mycobacterium avium complex (MAC). Therapeutic Effect Prevents MAC disease. 

The general mechanism of action of antimicrobial agents is listed in table 9.1.1. 

Leonard SN, Rybak MJ Telavancin An antimicrobial with a multifunctional mechanism of action for the treatment of serious gram-positive infections. Pharmacotherapy 2008 28 458. [PMID 18363530]... 

The cytokines are a large and heterogeneous group of proteins with diverse functions. Some are immunoregulatory proteins synthesized within lymphoreticular cells and play numerous interacting roles in the function of the immune system and in the control of hematopoiesis. The cytokines that have been clearly identified are summarized in Table 55-2. In most instances, cytokines mediate their effects through receptors on relevant target cells and appear to act in a manner similar to the mechanism of action of hormones. In other instances, cytokines may have antiproliferative, antimicrobial, and antitumor effects. 

Benzoyl peroxide is an effective topical agent in the treatment of acnevulgaris. It penetrates the stratum corneum or follicular openings unchanged and is converted metabolically to benzoic acid within the epidermis and dermis. Less than 5% of an applied dose is absorbed from the skin in an 8-hour period. It has been postulated that the mechanism of action of benzoyl peroxide in acne is related to its antimicrobial activity against P acnes and to its peeling and comedolytic effects. 

Azelaic acid is a straight-chain saturated dicarboxylic acid that is effective in the treatment of acnevulgaris (in the form of Azelex) and acne rosacea (Finacea). Its mechanism of action has not been fully determined, but preliminary studies demonstrate antimicrobial activity against P acnes as well as in vitro inhibitory effects on the conversion of testosterone to dihydrotestosterone. Initial therapy is begun with once-daily applications of the 20% cream or 15% gel to the affected areas for 1 week and twice-daily applications thereafter. Most patients experience mild irritation with redness and dryness of the skin during the first week of treatment. Clinical improvement is noted in 6-8 weeks of continuous therapy. 

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