Optimizing microbiological surveillance during selective digestive decontamination in the intensive care unit: an in silico simulation study

BACKGROUND: Selective Digestive Decontamination (SDD) prevents infections and reduces mortality in the intensive care unit (ICU). Microbiological surveillance is considered essential for effective decontamination and detecting antibiotic resistance. However, its optimal frequency is unclear. We compared microbiological yield and costs of different surveillance intervals during SDD.

METHODS: In a computational simulation study, using data from a Dutch ICU, three surveillance scenarios were compared: (A) twice-weekly, (B) once-weekly, and (C) no surveillance. The primary outcome was the number of clinically relevant potentially pathogenic microorganisms (PPMs) detected per scenario. Secondary outcomes included detection of colonisation persistence prompting SDD intensification and surveillance costs.

RESULTS: We included 8,499 ICU admissions, 52,553 clinical and 75,567 SDD cultures. Scenario A yielded 911 (95% CI 905-917) PPMs per 1,000 days, of which 90 (88-94) were clinically relevant: 9 (9-10) multidrug-resistant microorganisms, 68 (66-71) microorganisms resistant to standard therapy, and 13 (12-14) infection-related microorganisms. Scenarios B and C yielded 85 (82-88) and 77 (75-80) relevant PPMs, respectively (94% and 86% compared to scenario A). Scenario A identified 56 (55-58) cases of colonisation persistence per 1,000 days while scenarios B and C detected 43 (42-45) and 12 (11-12), respectively. Total costs of SDD surveillance were €78,774, €55,208, and €31,522 per 1,000 days for scenarios A, B and C.

CONCLUSION: Compared to twice-weekly surveillance, once-weekly microbiological surveillance reduces costs by 30% with 6% loss in clinically relevant PPM detections. No surveillance reduces costs by 60% with 14% detection loss.