In vitro potency of doripenem tested against an international collection of rarely isolated bacterial pathogens

Doripenem, a new 1β-methyl parenteral carbapenem, has very broad-spectrum activity against Gram-positive and Gram-negative aerobic bacteria. As noted here, the spectrum and potency extended to many rarely isolated species sampled by the Doripenem Global Surveillance Program. Among the species or species groups with ≤0.14% prevalence (1959 strains tested), doripenem was active against 98.9% of Enterobacteriaceae at ≤0.5 μg/mL. Similarly, more than 90% of other rarely isolated Gram-negative species isolates (Aeromonas spp., Delftia acidovorans, Haemophilus parainfluenzae, Neisseria meningitidis, Ochrobactrum anthropi, Pasteurella multocida, Pseudomonas oryzihabitans, and Pseudomonas stutzeri) were inhibited by ≤2 μg/mL of doripenem. The low-prevalence Gram-positive pathogens were generally less doripenem susceptible with MIC90 results at >0.25 μg/mL for all tested species except Lactococcus garvieae, Listeria monocytogenes, and Micrococcus spp. In conclusion, doripenem exhibited a very wide spectrum but variable potencies against uncommonly cultured aerobic bacterial pathogens isolated in 2003 to 2007. These results confirm the potential use of this new carbapenem for broad-spectrum empiric or directed antimicrobial therapy.