In vitro activity of Ro 09-1428 compared to other cephalosporins

Abstract

The in vitro activity of Ro 09-1428, a new catechol-type parenteral cephalosporin, was compared to that of ceftazidime, E-1040, cefpirome and cefepime against gram-positive and gramnegative organisms. Ro 09-1428 inhibited group A streptococci at ≤0.12 µg/ml, and group B, C and G streptococci andStreptococcus pneumoniae at 0.5 µg/ml, whereas forStaphylococcus aureus Ro 09-1428 had MICs of 8–16 µg/ml similar to ceftazidime and E-1040. AgainstPseudomonas aeruginosa Ro 09-1428 was the most active agent, inhibiting isolates at ≤0.12–2 µg/ml, and inhibited ceftazidime-resistant isolates. The majority ofEscherichia coli, Klebsiella spp.,Proteus mirabilis, Citrobacter diversus, Providencia, Salmonella andShigella were inhibited by ≤0.5 µg/ml as with the other cephalosporins. For mostCitrobacter freundii andEnterobacter cloacae Ro 09-1428 had higher MICs of 4–16 µg/ml; most ceftazidime-resistant isolates of these species were resistant. Anaerobes, enterococci andListeria monocytogenes were resistant to Ro 09-1428. Ro 09-1428 was not hydrolyzed by TEM-1, TEM-2,Staphylococcus aureus PC-1,Moraxella catarrhalis Bro-1,Enterobacter P-99,Pseudomonas aeruginosa Sabath-Abraham orKlebsiella beta-lactamases, but was hydrolyzed by TEM-3, TEM-7 and TEM-9. Ro 09-1428 was markedly less active at an acid pH.