Assessment of Doripenem, Meropenem, and Imipenem against Respiratory Isolates of Pseudomonas aeroginosa in a Tertiary Care Hospital of North India

Objective: Pseudomonas aeruginosa is one of the leading pathogen causing healthcare-associated infections, particularly in immunocompromised and critically ill patients. The development of carbapenem resistance in P. aeruginosa infections is worrisome. Data specifically comparing the susceptibility of the three available carbapenems are lacking in the Indian subcontinent. Materials and Methods: We evaluated the minimum inhibitory concentrations (MICs) of the three commonly used carbapenems-imipenem, meropenem, and doripenem against, 435 P. aeruginosa isolates obtained from respiratory samples and compared their susceptibility patterns to determine the best possible carbapenem among those available that may be used in combination regimes. Results: Overall, 222 (51.0%) of isolates were susceptible to doripenem followed by imipenem 206 (47.3%) and meropenem 195 (44.8%), respectively. Two hundred and sixty-two (60.23%) strains were intermediate or resistant to at least one carbapenem. The MIC90 of all three carbapenems was > 32 mu g/ ml while the MIC50 of meropenem was 16 mu g/ml which was higher than MIC50 of both imipenem (4 mu g/ml) and doripenem (2 mu g/ml). Conclusion: Our study revealed that doripenem exerted better in vitro activity against the tested bacteria compared to imipenem and meropenem, but the difference was not statistically significant.