Selective decontamination of the oropharynx and the digestive tract, and antimicrobial resistance: a 4 year ecological study in 38 intensive care units in the Netherlands

Objectives: Selective oropharyngeal decontamination (SOD) and selective decontamination of the digestive tract (SDD) are associated with improved outcomes among patients in intensive care units (ICUs), but uncertainty remains about their long-term effects on resistance levels. We determined trends in antibiotic resistance among Gram-negative bacteria in 38 Dutch ICUs using and not using SOD/SDD. Methods: The Infectious Disease Surveillance Information System-Antibiotic Resistance (ISIS-AR) was used to identify all Enterobacteriaceae, Pseudomonas aeruginosa and Acinetobacter spp. isolates from blood and respiratory tract specimens from ICUs between January 2008 and April 2012. Per patient, the last isolate per species per specimen per month was selected to determine cumulative resistance rates (per 100 beds/month) for colistin, tobramycin, ciprofloxacin, ceftazidime and cefotaxime/ceftriaxone in ICUs that continuously used or did not use SOD/SDD, and ICUs that introduced SOD/SDD. Time trends were analysed by multilevel Poisson regression. Results: Seventeen ICUs continuously used SOD/SDD (859 months), 13 did not use SOD/SDD (663 months) and 8 introduced SOD/SDD (223 and 117 months before and after introduction). There were no discernible trends in antibiotic resistance among 637 blood isolates. For the 8353 respiratory isolates, resistance to cefotaxime/ceftriaxone increased in ICUs that did not use SOD/SDD (P < 0.001) and decreased in those that continuously used SOD/SDD (P = 0.04), as did resistance to ciprofloxacin (P < 0.001). The introduction of SOD/SDD was followed by statistically significant reductions in resistance rates for all antimicrobial agents. Conclusions: Continuous use of SOD/SDD was associated with decreasing trends for resistance to cefotaxime/ceftriaxone and ciprofloxacin. The introduction of SOD/SDD was associated with reductions in resistance rates for all antimicrobial agents included.