Long-term (6-year) effect of selective digestive decontamination on antimicrobial resistance in intensive care, multiple-trauma patients

Objective. To determine whether selective digestive decontamination (SDD) had some negative impact on the bacterial resistance observed in strains isolated from samples from patients receiving nonabsorbable antibiotics and cefazolin. Design: Case-control study. Setting., Intensive care unit of a university tertiary-care hospital. Patients. Over a 6-yr period, 360 multiple trauma patients (case patients) submitted to SDD were compared with 360 patients not receiving SDD (controls). Interventions. SDD consisted of polymyxin E, gentamicin, and amphotericin B and was applied on the buccal mucosa and provided in the nares and the stomach. For the first 3 days, systemic cefazolin (1 g three times a day) was provided. Resistance analysis was performed in case patients and controls on samples collected at predetermined intervals. Measurements and Main Results: SDD was used in a small subset of patients admitted to the intensive care unit (360 of 5987 over the 6-yr study period). A relative overgrowth of gram-positive cocci was observed. Methicillin resistance of Staphylococcus epidermidis was increased (SDD 76%, controls 63%, p <.05) but not that of Staphylococcus aureus (SDD 20%, controls 18%). Resistance of Enterobacteriaceae, Pseudomonas aeruginosa, and Acinetobacter to beta-lactamines and aminoglycosides was the same in SOD patients and controls. Conclusions. When used in a small subset of patients who have been shown to derive benefit from it (patients who have experienced multiple trauma), SDD has a moderate impact on microbial ecology. However, surveillance cultures are indispensable because the absence of resistance to SDD antibiotics determines the long-term safety of the SDD prophylaxis.