Long-term use of selective decontamination of the digestive tract does not increase antibiotic resistance: a 5-year prospective cohort study

Despite the evidence, the use of selective decontamination of the digestive tract (SDD) remains controversial, largely because of concerns that it may promote the emergence of antibiotic-resistant strains. The purpose of this study was to evaluate the long-term incidence of carriage of antibiotic-resistant bacteria (ARB), its clinical impact on developing infections and to explore risk factors of acquiring resistance. This study was conducted in one 18-bed medical-surgical intensive care unit (ICU). All consecutive patients admitted to the ICU who were expected to require tracheal intubation for longer than 48 h were given a 4-day course of intravenous cefotaxime, and enteral polymyxin E, tobramycin, amphotericin B in an oropharyngeal paste and digestive solution. Oropharyngeal and rectal swabs were obtained on admission and once a week. Diagnostic samples were obtained on clinical indication. During 5 years 1,588 patients were included in the study. The incidence density of ARB was stable: 18.91 carriers per 1,000 patient-days. The incidence of resistant Enterobacteriaceae was stable; the resistance of Pseudomonas aeruginosa to tobramycin, amikacin and ciprofloxacin was strongly reduced; there was an increase of P. aeruginosa resistant to ceftazidime and imipenem, associated with the increase in imipenem consumption; the incidence of other nonfermenter bacilli and oxacillin-resistant Staphylococcus aureus was close to zero. Ninety-seven patients developed 101 infections caused by ARB: 23 pneumonias, 20 bloodstream infections and 58 urinary tract infections. Abdominal surgery was the only risk factor associated with ARB acquisition [risk ratio 1.56 (1.10-2.19)]. Long-term use of SDD is not associated with an increase in acquisition of resistant flora.