It has an inhibitory effect on a variety of Gram-positive and Gram-negative bacteria in vitro, and has a stronger inhibitory effect on hemolytic Streptococcus, Staphylococcus aureus, Vibrio cholerae, Neisseria meningitidis, Shigella, Salmonella typhi, Corynebacterium diphtheriae, etc. It also has a certain inhibitory effect on amoeba.

It mainly interferes with bacterial folate metabolism, selectively inhibits dihydrofolate reductase, and prevents nucleic acid synthesis.

It has high antibacterial activity against most aerobic Gram-negative bacteria, including Escherichia coli, Klebsiella pneumoniae and Oxytobacter, aerogenes, Cloacae, Proteus, Serratia, Citrobacter, Shigella and other Enterobacteriaceae, as well as influenza bacilli, gonococci, meningococci, etc. It also has good antibacterial effect against Pseudomonas aeruginosa, but has poor antibacterial effect against some Pseudomonas and Acinetobacter species other than Pseudomonas aeruginosa, and has no antibacterial activity against aerobic Gram-positive bacteria such as Staphylococcus and Streptococcus, as well as anaerobic bacteria. Aztreonam inhibits cell wall synthesis by highly binding to penicillin-binding protein 3 (PBP3) on the cell membrane of sensitive aerobic Gram-negative bacteria. Unlike most β-lactam antibiotics, it does not induce bacteria to produce β-lactamases, and is highly stable to most β-lactamases produced by bacteria.

It has high antibacterial activity against most aerobic Gram-negative bacteria, including Escherichia coli, Klebsiella pneumoniae and Oxytobacter, aerogenes, Cloacae, Proteus, Serratia, Citrobacter, Shigella and other Enterobacteriaceae, as well as influenza bacilli, gonococci, meningococci, etc. It also has good antibacterial effect against Pseudomonas aeruginosa, but has poor antibacterial effect against some Pseudomonas and Acinetobacter species other than Pseudomonas aeruginosa, and has no antibacterial activity against aerobic Gram-positive bacteria such as Staphylococcus and Streptococcus, as well as anaerobic bacteria. Aztreonam exerts its antibacterial effect by binding to penicillin-binding protein 3 (PBP3) on the cell membrane of sensitive aerobic Gram-negative bacteria and interfering with the synthesis of bacterial cell walls.