N.D. Goldstein, S.M. Jenness, D. Tuttle, M. Power, D.A. Paul, S.C. Eppes

Surveillance for meticillin-resistant Staphylococcus aureus (MRSA) in neonatal intensive care units (NICUs) is a commonplace infection prevention strategy, yet the optimal frequency with which to monitor the unit is unknown. We compared varying surveillance frequencies via simulation modelling. One hundred NICU networks of 52 infants were simulated over a 6-month period to assess MRSA transmission. Unit-wide surveillance occurred every N weeks where N={1,2,3,4}, and was compared against the current NICU policy of dynamic surveillance: weekly when ≥1 positive screen, otherwise every 3 weeks. At each surveillance period, colonised infants received a decolonisation regimen (56% effective) and were moved to isolation rooms, if available. As the surveillance frequency increased, the mean number of MRSA colonised infants decreased, from a high of 2.9 (monitoring every 4 weeks) to a low of 0.6 (monitoring every week) detected per episode. Mean duration of colonisation similarly decreased from 307 hrs (monitoring every 4 weeks) to 61 hrs (monitoring every week). Meanwhile the availability of isolation rooms followed an inverse relationship: as frequency increased, the availability of rooms decreased (61% isolation success rate every 4 weeks vs. 49% success rate every week). The dynamic policy performed similar to a biweekly programme. An effective MRSA surveillance programme needs to balance resource availability with potential for harm due to longer colonisation periods and opportunity for development of invasive disease. While more frequent monitoring led to greater use of a decolonisation regimen, it also reduced the likelihood of isolation rooms being available.