ABSTRACT
Maclorides were mainly administered as second-choice antibiotics to patients allergic to penicillins and cephalosporins, and to outpatients with respiratory tract infections caused by susceptible Gram-positive organisms. It is well known that the discovery of penicillin by Alexander Fleming in 1929, which led to the isolation and development of penicillin in the mid-1940s, was the beginning of an era of β-lactam antibiotics that continues to this day. β-lactams inactivate various penicillin-binding proteins in bacteral cell membranes by acylating a serin residue in their aminoacid sequences. Macrolides inhibit RNA-dependent protein synthesis by stimulating the dissociation of peptidyl tRNA from ribosomes. Recently, modification of erythromycin was investigated. In general, β-lactam antibiotics, such as cephalosporins, are classified as poorly absorptive drugs from the pKa value of their carboxylic acid group. Amino-β-lactams such as cephalexin and cefaclor, are exceptionally absorbed by the carrier-mediated mechanism. Novel oral cephalosporins corresponding to the third-generation cephalosporins were extensively studied.
