About cefalexina first-generation cephalosporin antibiotic.ssmechanism of action scephalexin is a 1st generation cephalosporin which exerts its bactericidal action against both gram positive & gram negative organisms by inhibiting bacterial cell wall synthesis. cephalexin inhibits transpeptidase & thus prevents cross linking of bacterial cell wall. transpeptidase & associated proteins constitute various types of specific binding proteins which have affinity for cephalosporins like cephalexin ssindications for cefalexins1.respiratory tract infections s2.urinary tract infections s3.surgical prophylaxis s4.skin infections` s5.joint & bone infections s6.otitis media` s7.reproductive tract infections` sscontra-indicationss1.hypersensitivity to cephalosporins s2.porphyria s3.neuromuscular disorders.