Line graph demonstrates the percentage of E. faecium resistant to ampicillin, by survey year. Survey years include 1995, 1999, 2003, 2005, 2007, 2009 and 2010. The figure includes line graphs for invasive, non invasive, and all isolates

From 1995 to 1999 there was a significant increase in ampicillin resistance (P=0.0017) with a plateau from 1999 to 2005. Between 2005 and 2010 resistance increased significantly (P=0.005). The gap between resistance in non-invasive versus invasive isolates narrowed over time, however in 2010 there was a reversal of this trend with rates of resistance in invasive isolates falling significantly (P=0.04) compared to 2009 levels