Experience intracking Colonization and Infection in the Pediatric (PICU) and Neonatal (NICU) Intensive Care Units

Background: Staphylococcus Aureus (SA) infections are endemic in our environment.  Methicillin resistant SA (MRSA) infections account for approximately half of the Community acquired (CA) and Hospital acquired (HA) infections. 

Objective: To review effects of routine admission and weekly SA colonization surveys in the PICU & NICU.

Methods:  Observational study after introducing routine admission and weekly follow-up nasal cultures for SA, MSSA & MRSA from April 2008 - June 2010.  Colonized patients were placed in contact isolation. Standard Infection control practices were emphasized in both ICUs.  The IHI Central Line Bundle and the VAP Prevention Bundle had been implemented in the PICU.  The Central Line Bundle and universal daily application of nasal mupirocin to all infants were implemented in the NICU in December 2005. 

Results: PICU - Monthly rates for SA colonization ranged from 2 to 6.5 per 100 patient days.  MRSA accounted for 23% of colonizations ranging from 8-60% of total SA per month.  Weekly colonization rate ranged from 16% to 30%.  Most were colonized on admission, only 15 (6 %) of those ever colonized acquired colonization in PICU  All SA infections , 6 MSSA and 7 MRSA , were present on admission. 

NICU - Monthly rates for SA colonization ranged from 0 (5 months) to 0.6/100 patient days.  Among those SA colonized and/or infected, there were nearly equal numbers of MSSA (34) and MRSA (36).   Weekly surveys ranged from 0% to 20% but averaged less than 5% except for the period from December 2008 to May 2009 when weekly rates exceeded 10% and multiple iSA infections occurred.   Overall, SA colonization was present for 66 (4%) of 1620 (33 MSSA and 33 MRSA).  38 colonized on admission, 23 developed SA colonization or infection after admission.  NICU acquired SA infections occurred in 16 infants: 1 MSSA (bacteremia) and 15 MRSA (3 bacteremia). SA colonization predicted later SA infection.  12 of 66 (18%) with SA colonization developed SA infection vs. 4 of 1554 non-colonized.  (Fisher Exact p=0.0002 OR 86 95% CI 27-275).  For MRSA, 12 infections developed in 33 colonized vs. 3 in 1588 never colonized.  (p<0.0001 OR 302 95% CI 79->999.9) MSSA bacteremia developed in 1 non-colonized patient. Prior to introducing universal daily nasal mupirocin in December 2005, weekly SA colonization ranged from 15-60%. With universal mupirocin, the rate for all SA infections fell from 3.9 ( 2003-12/2005) to 2/1000 patient days (p=0.0002).

Conclusions: SA colonization patterns differ in the PICU vs. NICU.  PICU colonization rates are approximately 10 X higher but few later colonizations and no Healthcare Associated Infection (HAI) occured. For us, PICU colonization surveys & isolation are not cost effective. For NICU, SA colonization predicted later HAI for MRSA but not for MSSA despite equal exposure. thus efforts to delay and prevent SA colonization are high priority.  Universal daily mupirocin acts as a barrier to colonization and infection.