In vitro activity of cefquinome, a new cephalosporin, compared with other cephalosporin antibiotics

Abstract

The in vitro activity of cefquinome, a new aminothiazolyl cephalosporin with a C-3 bicyclic pyridinium group, was compared with ceftazidime, cefpirome, and cefepime. Cefquinome inhibited members of the Enterobacteriaceae at ≤ 0.5 μg/ml for Escherichia coli, Klebsiella pneumoniae, K. oxytoca, Citrobacter diversus, Salmonella Shigella, Proteus mirabilis, Morganella, and Providencia. Although most Citrobacter freundii and Enterobacter cloacae were inhibited by < 2 μg/ml, some strains resistant to ceftazidime were resistant, [minimum inhibitory concentration (MIC) > 16 μg/ml]. Serratia marcescens were inhibited by < 1 μg/ml and Pseudomonas aeruginosa by 8 μg/ml similar to the activity of cefepime. The majority of Haemophilus influenzae and Neisseria gonorrhoeae were inhibited by < 0.25 μg/ml. Most enterococci had cequinome MICs of 4–8 μg/ml. Cefquinome was extremely active against group-A streptococci and Streptococcus pneumoniae with MICs < 0.12 μg/ml. 90% of methicillin-susceptible Staphylococcus aureus 90% were inhibited by 2 μg/ml. Overall, the in vitro activity of cefquinome was comparable with aminothiazolyl cephalosporins. It inhibited some Enterobacter and Citrobacter freundii resistant to ceftazidime as did cefpirome and cefepime. Cefquinome was not destroyed by the common plasmid β-lactamases TEM-1, TEM-2, SHV-1, or by the chromosomal β-lactamases of Klebsiella, Branhamella, and Pseudomonas, but it was hydrolyzed by TEM-3, TEM-5, and TEM-9. Its activity was not adversely decreased in different medium or protein, and minimum bactericidal concentrations (MBCs) for most species except for Enterobacter were within a dilution of MICs.