Cephalexin (cefalexin)  has antimicrobial activity against gram-negative bacteria such as Escherichia coli, Aerogenes, Klebsiella, Proteus singular, some indole-positive Proteus, Pseudomonas aeruginosa, some Neisseria, some Serrae anpigmentum and Shigella.
Among gram-positive bacteria, Staphylococcus aureus (including β-lactamase producing strains) were sensitive to this product;
Streptococcus (including suppurative streptococcus, pneumonic streptococcus, faecal streptococcus, etc.) are resistant to this product.
Anaerobes (Bacteroides), Mycobacterium tuberculosis, Rickettsia, fungi and viruses are also resistant to this product.
In recent years, due to the wide application of this product, drug-resistant strains gradually increased, and the drug resistance rate of Pseudomonas aeruginosa, Klebsiella, Serratia and Indobacter positive proteus was very high.
Gentamicin is mainly used for systemic or local infections caused by Gram-negative bacteria such as Escherichia coli, Shigella dysenteriae, Klebsiella pneumoniae, proteus and Pseudomonas aeruginosa (ineffective for central infections).

Function
Cephalexin is the first semi-synthetic oral cephalosporin. Its mechanism of action is to inhibit cell wall synthesis of bacterial mitotic cells by binding with one or more penicillin-binding proteins of bacteria, thus playing an antimicrobial role. The antimicrobial spectrum of Cefalexin is similar to that of cefathiophene, but its antimicrobial activity is worse than that of cefalexin. Gram-positive cocci were sensitive to Cefalexin except Enterococcus and methicillin-resistant

Application
Cephalexin is mainly used for gram-positive and negative bacterial infections, such as influenza, hemorrhagic septicemia, Streptococcosis, swine erysipelas, anthrax, emphysematous, malignant edema, actinomycosis, necrotizing bacilli, leptospirosis, etc., caused by septic hyperthermia (41~43 degrees Celsius) or continuous hypothermia (below 37 degrees Celsius), dyspepsia, cold water, no lethargy, and so on. Walking limp, ear blue, tears, etc.