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

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Abstract
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. Case-control study. Intensive care unit of a university tertiary-care hospital. Over a 6-yr period, 360 multiple trauma patients (case patients) submitted to SDD were compared with 360 patients not receiving SDD (controls). 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. 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 SDD patients and controls. 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.