Ceftriaxone has bactericidal activity by inhibiting the synthesis of cell wall. Ceftriaxone has bactericidal effect on many Gram-positive bacteria and Gram-negative bacteria in vitro, and has high stability on most β -lactamases (penicillinase and cephalosporinase) of Gram-positive bacteria and Gram-negative bacteria. Ceftriaxone usually has antibacterial effect on the following pathogenic bacteria in vitro test and clinical infection (see indications). Treponema pallidum is sensitive to ceftriaxone in vitro and animal experiments. Clinical investigation showed that primary and secondary syphilis responded well to ceftriaxone, and Pseudomonas aeruginosa was resistant to ceftriaxone except for a small part. In vitro experiments showed that ceftriaxone was active against some cephalosporins which were resistant by disk method, so ceftriaxone disk method should be used for drug sensitivity test. The standards recommended by the National Clinical Laboratory Standards Committee are not routinely used. Very standardized drug sensitivity standards issued by DIN, ICS and other organizations can also be replaced.