Cefapirin is the first generation cephalosporin antibiotic. Cefapirin is broadly effective against gram-negative and gram-positive bacteria [1].

The antibacterial action of cefapirin was due to the inhibition of cell-wall synthesis, mediated by its binding to penicillin binding proteins. It was mainly used in veterinary medicine for intramammary treatment of mastitis and intrauterine treatment of endometritis in cattle [1,2].

Cefapirin was an antibiotic particularly suitable for the treatment of acute otitis media. In 210 strains isolated from the auricular exudate of childrens' acute otitis media, the MIC50 and MIC90 of cefapirin were 2 and 4 mg/l for 112 strains of Haemophilus. The MIC ranged from 0.25 to 4 mg/l for ten strains of Branhamella catarrhalis (9 secreted a beta-lactamase). Cefapirin had an extremely high activity with MIC50 and 90 less than 0.06 mg/l against Streptococcus pneumoniae. For the strains of Staphylococcus aureus sensitive to meticillin, one had a MIC less than 0.06 mg/l, and 11 had a MIC of 0.25 mg/l. For 14 strains of Enterobacteriaceae studied, the MIC 50 was 8 mg/l and the MIC 90 was 32 mg/l [3].

References:
[1] Committee for veterinary medicinal products: Cefapririn.  EMEA, 1-6 (2001).
[2] Ray, P. ,Knowlton, K.F.,Shang, C., et al. Development and validation of a UPLC-MS/MS method to monitor cephapirin excretion in dairy cows following intramammary infusion. PLoS One 9(11), 1-12 (2014).
[3] Simonet M, Herrmann J L, Gehanno P, et al.  Activity of cefapirin against bacterial strains isolated from acute otitis media in children[J]. Pathologie-biologie, 1990, 38(5): 352-354.