Interpreting carbapenem susceptibility testing results for Pseudomonas aeruginosa.

OBJECTIVES: Carbapenems are among the most powerful antipseudomonal agents. Limited data is available on drug susceptibility testing by routine methods (disc diffusion and Etest) for meropenem and doripenem. We aimed to compare the in vitro activity of imipenem, meropenem, and doripenem against Pseudomonas aeruginosa. METHODS: A total of 311 P. aeruginosa strains isolated from respiratory specimens in 170 patients who developed ventilator-associated pneumonia in two intensive care units were collected over a period of 31 months. The susceptibility of these isolates to imipenem, meropenem, and doripenem were determined by Etest and disc diffusion method. RESULTS: Considering either all isolates or only the first isolates recovered per patient (311 and 170 respectively), the susceptibility rate for doripenem was higher than that for meropenem and imipenem. When MICs determined by Etest were converted into interpretative categories (S, I, R) using French (CA-SFM) guidelines, a poor correlation was observed for meropenem and doripenem. The percentages of correlation with the disc diffusion method were 90.6% and 89.7% for imipenem, 80.5% and 82.6% for meropenem, and 80.5% and 73.3% for doripenem, for the first isolates and all isolates, respectively. The rate of minor errors was as high as 17.7% and 16.1% for meropenem and 17.7% and 25.7% for doripenem for the first isolates and all isolates, respectively. CONCLUSION: The accuracy of disc diffusion using CA-SFM guidelines appears unsatisfactory for all three carbapenems justifying guideline update for P. aeruginosa and carbapenems.

Indications for extracorporeal support: why do we need the results of the EOLIA trial?

Acute respiratory distress syndrome (ARDS) is a severe lung disease, with an associated mortality rate exceeding 60% for the most severe forms of the disease. In these situations, establishing an extracorporeal circuit, combining a centrifugal pump and a membrane oxygenator (extra-corporeal membrane oxygenation, ECMO), can ensure total pulmonary assistance and allow the lungs to rest under ultraprotective mechanical ventilation. Unfortunately, former trials of ECMO in ARDS were negative or highly criticized due to many technical and methodological shortcomings. Prior to the widespread use of venovenous ECMO for severe ARDS, new trials are needed to test the efficacy of early initiation of the technique with tight control of mechanical ventilation in the control group, initiation of ECMO prior to transportation to ECMO centers, and the use of ECMO in all patients randomly assigned to receive this treatment. Therefore, the international multicenter randomized EOLIA (ECMO to rescue Lung Injury in severe ARDS) trial was designed to test the benefit of systematic and early installation of the latest-generation ECMO circuits in patients with very severe ARDS. Patients randomized to the control group were managed with tight control of mechanical ventilation and recourse to paralyzing agents and prone positioning, while an ethical crossover option to ECMO was permitted only if refractory hypoxemia (SaO2 < 80%) lasted for > 6 h despite all possible conventional emergency interventions. The primary endpoint of the study was the 60-day mortality rate, with an expected 20% absolute mortality reduction with ECMO.