Linezolid better than Vancomycin in Ventilator Associated Pneumonia?: Maybe… Maybe Not

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Ventilator associated pneumonia (VAP) is a problem in ICU around the world and methicillin-resistant Staphylococcus aureus (MRSA) is the most common multi-drug resistant pathogen to deal with. Current guidelines mostly recommend vancomycin as a first line treatment and linezolid as an alternative, considering both drugs at a similar level of efficacy. The question remained whether linezolid might be superior to vancomycin.

So far only one prospective, randomised, double-blind trial looked at this question and found a better success rate for linezolid, which was not statistically significant though.

To look at this issue the IMPACT-HAP investigators (Improving Medicine through Pathway Assessment of Critical Therapy in Hospital Acquired Pneumonia) performed a multicenter, retrospective, observational study on 188 patients in 5 hospitals of the U.S.

They found a significantly higher success rate with linezolid compared to vancomycin in the means of improvement or resolution of the signs and symptoms of VAP (primary endpoint). The study did not identify any difference though between linezolid- and vancomycin-treated patients in regards to mortality, development of thrombocytopenia, anaemia, or nephrotoxicity, days of mechanical ventilation or length of stay ion ICU or the hospital itself (secondary outcomes).

Looking into the trial there appear to be several confounding reasons why patients treated with linezolid had better clinical success rate like less severity of sickness in linezolid patients, possible suboptimal vancomycin through levels etc.
Overall there seems no good reasons at this stage to change current guidelines.
Wunderink RG et al. Linezolid in methicillin-resistant Staphylococcus aureus nosocomial pneumonia, Clin Infect Dis; 2012, 54:621–629

Peyrani P et al. Crit Care 2014; 18:R118 doi:10.1186/cc13914