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Chapter 6 : Antibiotics and Synthetic Antibacterial Agents
In this chapter, the antibiotics and synthetic antibacterials are grouped on the basis of their chemical structure and by mechanism of action. Substructure groups are the penicillins, the cephalosporins, the carbapenems, the monobactams, and the β-lactam derivatives clavulanic acid, sulbactam and tazobactam, which are β-lactamase inhibitors. Fosfomycin [L-(cis)-1,2-epoxypropylphosphonic acid] (formerly known as phosphonomycin) is a naturally occurring antibiotic obtained from species of Streptomyces. The nitrofurans are a class of synthetic antibacterial agents characterized by the presence of a 5-nitro-2-furanoyl group. Some of the antibiotics that interfere with the biosynthesis of peptidoglycan are β-lactams (penicillins, cephalosporins, cephamycins, monobactams, and carbapenems), glycopeptides (vancomycin and teicoplanin), D-cycloserine, fosfomycin, and bacitracin. The bactericidal activity of the polymyxins and cationic antimicrobial peptides results from their interaction with the bacterial cytoplasmic membrane, causing gross disorganization of its structure. For growth and multiplication, microorganisms conduct a variety of biochemical and metabolic processes to obtain energy and new cell material. All industrial microbiology processes require the initial isolation of microorganisms from nature. Antibiotic-producing microorganisms are subjected to extensive genetic manipulations and modifications before they are used for antibiotic-manufacturing purposes. Nonpolar antibiotics are usually purified by solvent extraction procedures; water-soluble compounds are commonly purified by ion-exchange methods or chemical precipitation.