Selective decontamination of the digestive tract: a life saver

Selective decontamination of the digestive tract (SDD), a strategy designed to prevent or minimize the impact of infection by potentially pathogenic m icro-organisms in critically ill patients requiring long-term mechanical ve ntilation, comprises four component protocols, aiming to control the three types of infection occurring ill such cases: (i) a parenteral antibiotic, c efotaxime, administered fur a few days to prevent primary endogenous infect ions typically occurring 'early'; (ii) the topical antimicrobials polymyxin E, tobramycin and amphotericin B employed throughout the stay in the inten sive care unit to prevent secondary endogenous infections tending to develo p 'late'; (iii) a high standard of hygiene to prevent exogenous infections that may occur throughout the stay in the intensive care unit; (iv) surveil lance samples of throat and rectum to distinguish between these three types of infection, to monitor the compliance and the efficacy of the treatment, and to detect the emergence of resistance at an early stage. A recent, rig orous, meta-analysis examining 33 randomized SDD trials involving 5727 pati ents demonstrated a significant reduction in overall mortality (20%) and in the incidence of respiratory tract infections (65%); conclusive evidence t hat SDD saves the lives of critically ill patients and confirmation that SD D is now an evidence based medicine manoeuvre. This same meta-analysis foun d no instance of the emergence of resistance or of associated superinfectio ns and/or outbreaks in any of the 33 studies during a period extending upwa rds of 10 years. By the criterion of cost-per-survivor, four recent randomi zed trials showed that patient survival is improved more cheaply by employi ng SDD than by the traditional approaches. (C) 2000 The Hospital infection Society.