In vitro activity has been demonstrated against common Gram positive and Gram negative bacteria including Escherichia coli, Citrobacter spp., Klebsiella spp., Mannheimia haemolytica, Pasteurella multocida, Proteus spp., Salmonella spp., Serratia marcescens, Haemophilus somnus, Arcanobacterium pyogenes, Bacillus spp., Corynebacterium spp., Staphylococcus spp., Streptococcus spp., Bacteroides spp., Clostridium spp., Fusobacterium spp., Prevotella spp., Actinobacillus spp. and Erysipelothrix rhusiopathiae.

Bacterial strains were isolated between 1999 and 2002 from cattle and pigs presenting diseases corresponding to target indications in Germany, France, The Netherlands and United Kingdom. From a sample of more than 350 isolates, 97.7% were found to be susceptible to cefquinome (resistance breakpoint of 4 µg/mL). These susceptible strains had MIC levels ranging from < 0.004 to 2 µg/mL.

Cefquinome as a fourth generation cephalosporin combines high cellular penetration and ß-lactamase stability. In contrast to cephalosporins of previous generations, cefquinome is not hydrolysed by chromosomally–encoded cephalosporinases of the Amp-C type or by plasmid mediated cephalosporinases of some enterobacterial species. However, some Extended Spectrum beta-lactamases (ESBL) can hydrolyse cefquinome and cephalosporins of other generations. The potential for resistance development against cefquinome is rather low. High-level resistance to cefquinome would require the coincidence of two genetic modifications, i.e. hyperproduction of specific ß-lactamases as well as decreased membrane permeability.

In cattle peak serum concentrations of about 2 µg/ml are reached within 1.5-2 hours after intramuscular or subcutaneous administration at the dose of 1 mg/kg. Cefquinome has a relatively short half-life (2.5 hours), is < 5 % protein bound and excreted unchanged in the urine. Cefquinome is not absorbed after oral administration.

In pigs or piglets, at 2 mg/kg dosage, maximum serum concentrations of around 5 µg/ml are measured within 15 to 60 minutes after intramuscular injection. The average half-life is about 9 hours.

Cefquinome binds poorly to plasma proteins and therefore penetrates into the cerebrospinal fluid (CSF) and the synovial fluid in pigs. The concentration profile is similar between the synovial fluid and the plasma. The concentrations reached in the CSF 12 hours after treatment are similar to those in plasma.