or in combination with other drugs [21]. In experimental pneumonias caused by pan-resistant A. baumannii, colistin combined with rifampicin is superior to monotherapy with
colistin [14]. This superiority of the combined treatment has not been demonstrated in clinical trials. Two clinical trials have compared colistin plus rifampicin versus colistin
alone, one in patients suffering from VAP caused by A.baumannii and the other one including patients suffering from several infections including VAP, with disappointing
results [22,23]. In this context of multi-resistance complicating the treatment of VAP, in many centers the definition of the optimal treatment has turned into a public health priority, as has the improvement of the methods for early microbiological diagnosis