All drug inhibit bacterial cell wall synthesis EXCEPT
Spectinomycin is an aminocyclitol antibiotic that inhibits bacterial protein synthesis. The other drugs all inhibit bacterial cell wall synthesis. Vancomycin and bacitracin inhibit early steps in the biosynthesis of the peptidoglycan component of the cell wall, whereas 3-- lactams such as aztreonam (a monobactam), penicillins, cephalosporins, and carbapenems inhibit the cross-linking (transpeptidation) of the cell wall peptidoglycan polymers.
Spectinomycin
Vancomycin
Aztreonam
Cephalexin