Synthesis and antimicrobial evaluation of some cephem derivatives

Two novel cephem derivative series were synthesized: 7-(D-alpha-aminophenyl-acetamido-)-3-methyl-3-cephem-4-carboxylic acid monohydrate (Cephalexin) derivatives and those of 7-amino-3-(1-methyl-1H-tetrazol-5-yl)-thio methyl-3-cephem-4-carboxylic acid (7-AMTCA). The antimicrobial activity of the prepared compounds was studied and compared to that of known cephalosporin antibiotics of the first generation against 12 standard strains and 189 clinical isolates of Gram-positive and Gram-negative microorganisms. The Cephalexin derivatives 4a-f show a narrow activity spectrum and are inactive while 5c and 5d are more active than the Cephalexin and Cephazolin antibiotics against clinically isolated S. aureus and S. epidermidis strains.