In the recent years, selective decontamination of the digestive tract (SDD) is one of the most extensively studied prevention strategy in VAP. In SDD, topical non-absorbed antimicrobials (usually combining polymyxin, aminoglycoside and amphotericin B) are used to prevent gastrointestinal colonisation by pathogenic microorganisms. It selectively eradicates the potential pathogenic microorganisms (gram-negative aerobic intestinal bacteria, S. aureus and fungi) and does not affect anaerobic flora, as elimination of anaerobic flora leads to increased colonization with gram-negative aerobic flora. Although some investigators used only topical antibiotics applied to the oropharynx and through a nasogastric tube, many of them added systemic therapy with a broad spectrum (e.g. cefotaxime) during the first few days, to prevent early infections with S. pneumoniae, H. influenzae and S. aureus [29] . In a recent meta-analysis that searched 33 randomized controlled trials published from 1984 to 1996, significant reductions in the incidence of respiratory tract infections (65%) and in total mortality (20%) were determined [135] . Also in this meta-analysis and in the other recent prospective, randomized studies, it was mentioned that using only topical antibiotics reduced respiratory infections, but did not influence the survival [135] [136] [137] .