Effects of long-term routine use of selective digestive decontamination on antimicrobial resistance.

OBJECTIVE

To assess the distribution of bacterial species and antimicrobial resistance in an ICU during long-term use of selective digestive decontamination (SDD) in the context of national reference data.

DESIGN AND SETTING

Five-year prospective observational study in a 24-bed interdisciplinary surgical ICU of a university hospital (study ICU) participating in the project "Surveillance of Antimicrobial Use and Antimicrobial Resistance in German Intensive Care Units" (SARI; reference ICUs).

PATIENTS

Resistance data were obtained from all patients; patients intubated for at least 2 days received SDD (colistin, tobramycin, amphotericin B).

INTERVENTIONS AND MEASUREMENTS

SDD was performed in 1,913 of 7,270 patients. Antimicrobial resistance was examined in 4,597 (study ICU) and 46,346 (reference ICUs) isolates.

RESULTS

Methicillin-resistant Staphylococcus aureus (MRSA) remained stable (2.76 and 2.58 isolates/1000 patient days) in the study ICU; this was below the German average (4.26 isolates/1000 patient days). Aminoglycoside- and betalactam-resistant Gram-negative rods did not increase during SDD use. Aminoglycoside resistance of Pseudomonas aeruginosa was 50% below the mean value of SARI (0.24 vs. 0.52 isolates/1,000 patient days). The relative frequency of enterococci and coagulase-negative staphylococci (CNS) was higher than in the SARI ICUs (23.2% vs. 17.3%, and 25.0% vs. 20.6%, respectively).

CONCLUSION

Routine 5-year-use of SDD was not associated with increased antimicrobial resistance in our ICU with low baseline resistance rates. Vigorous surveillance and control measures to search and destroy MRSA were considered a mandatory component of the SDD program. The relative increase in enterococci and CNS is of concern requiring further investigation.